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Copyright 2005 Wood-Mizer Products, Inc.

8180 West 10th StreetIndianapolis, IN 46214

800.553.0182 woodmizer.com

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WOODSWOODSHOP

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A Guide for Producing the Best Lumber

By Gene Wengert

Presented by Wood-Mizer

$5.00

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PART 1 Sawing the Best LumberLOG QUALITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

SAWMILLING QUALITY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

HARDWOOD SAWING TECHNIQUES

Hardwood Lumber Grades and Prices. . . . . . . . . . . . . . . . . . . . . . 7-8

Hardwood Sawing Patterns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Opening Face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Specific Sawing Suggestions

General Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Log Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Opening Face Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Sweepy Logs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Quartersawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

SOFTWOOD SAWING TECHNIQUESawing Softwood Logs Into Construction Lumber . . . . . . . . . . 14

Sawing Softwood Logs into Boards and Lumber for

Remanufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

PART 2 Drying the Best LumberWHY DRY LUMBER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

MEASURING MOISTURE CONTENT. . . . . . . . . . . . . . . . . . . . . . . 17

WATER IN THE WOOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

AS SOON AS THE LUMBER IS SAWN...

Drying Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Stacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

LUMBER DRYING

Initial Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Air-Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Kiln-Drying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

WOODSWOODSHOP

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A Guide for Producing the Best Lumber

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Drying Source Book: 40 Years of Drying ExperienceEdited by E. M. Wengert and R. Toennisson. Available from Forest Products Society, 2801 Marshall Ct., Madison, WI 53705.

Drying Hardwood Lumber, By J.Denig, G. Wengert and W. Simpson. Available (free) from Publications Department, Wood Eduction & Resource Center, 301 Hardwood Lane, Princeton, WV 24740.

Drying Oak Lumber, By E.M. Wengert. Available from University of Wisconsin--Forestry Dept., 1630 Linden Dr., Madison, WI 53706.

Opportunities for Dehumidification Drying of Hardwood LumberBy E.M. Wengert & OthersAvailable from Virginia Forest Products Association, P.O. Box 160, Sandston, VA 23150.

Applied Drying Technology, 1988 to 1993; and Applied Drying Technology, 1978-1988, By M. R. Milota and E.M. Wengert. Available from Forest Products Society, 2801 Marshall Ct., Madison, WI 53705.

Dry Kiln Operator's ManualEdited by W. T. Simpson and Others. Available from Forest Products Society, 2801 Marshall Ct., Madison, WI 53705.

Dry Kiln Schedules for Commercial WoodsBy R.S. Boone and Others. Available from Forest Products Society, 2801 Marshall Ct., Madison, WI 53705.

Design and Operation of a Solar-Heated Dry KilnBy Brian Bond. Publication 420-030, Dept. of Wood Science and Forest Products, Virginia Tech, Blackburg, VA 24061.

Web Site: www.woodweb.com (Sawing and Drying Message Board)

Sawing and Grading

Rules for the Measurement & Inspection of Hardwood and Cypress Written by and available from NHLA, P.O. Box 34518, Memphis, TN 38184.

NHLA Inspection School ManualWritten by and available from NHLA, P.O. Box 34518, Memphis, TN 38184.

What is hardwood? How is it graded? (14-minute video)Produced by and available from NHLA, P.O. Box 34518, Memphis, TN 38184.

Basics of hardwood lumber grades (10-minute video)Produced by and available from NHLA, P.O. Box 34518, Memphis, TN 38184.

Small Sawmill Handbook: Doing It Right and Making MoneyWritten by Joe DenigAvailable from the Forest products Society,2801 Marshall Ct. Madison, WI 53705.

Sawing, Edging and Trimming Hardwood Lumber By Joe Denig and Gene Wengert. Available from the Forest products Society, 2801 Marshall Ct. Madison, WI 53705.

Lumber yard insects (22-minute video)Produced by and available from NC State University, Campus Box 7603, Raleigh, NC 27695-7603.

Wood Using IndustriesDirectories are usually issued by most state every few years. Contact the state Department of Natural Resources, Forest Products Utilization Specialist.

Web Site: www.woodweb.com (Sawing and Drying Discussion /Message Board).

Sawmill & Woodlot Management magazine (targeting small producers). Subscription information available at www.sawmillmag.com

PART 3 Additional ResourcesContact the sources listed to determine availability and cost. Most of the items listed will require prepayment.

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Oven-dryingIn the oven-dry test, a small piece of wood (called a moisture section) representing a large piece of lum-ber is first weighed. The weighing is typically to the closest 0.01 ounces, so a postal scale is not accu-rate enough. Then the moisture section is put in an oven heated to 215 F. (A kitchen-type microwave can also be used if the oven has a carousel tray, and is set to medium low for 20 to 40 minutes. Do not leave the oven unattended, however, as the section sometimes may begin to smoke.) After approximately 24 hours, the section is weighed again, dried for one more hour, and then weighed again. If these two final weights are the same, then all the moisture has been evaporated; the section weight is the oven-dry weight. The MC is calculated using this formula:

An alternate formula is:

Electric MetersThe oven-drying test is a destructive test and requires 24 hours to get the reading. The MC can be measured rapidly and non-destructively by using electrical methods. It was discovered years ago that the electrical resistance is fairly well-related to MC. With the meter, pins are driven into the lumber and the resistance between the pins is measured. A second relationship was discovered between the dielectric coefficient and the MC. Meters based on this principle use a flat plate that is intimate contact with the wood.

Both types of meters are fairly accurate estimators of the MC. Each also has certain advantages and certain disadvantages. For example, the resistant meter can measure a gradient, depending on how far the pins are driven into the lumber. The resis-tance meter also is not strongly affected by different species. The dielectric meter is not affected by the temperature of the wood. The dielectric meter can also quickly scan the lumber’s surface looking for wet spots or wet pieces. Anyone kiln drying wood needs to have both types of meters—the best meter is always the same one that your customer is using!

The disadvantage of both meters is that they can-not be accurately used above 30% MC. That means that they cannot be used to run a kiln drying lumber “green from the saw.” The oven-drying procedure is the only reliable MC measuring system for kiln oper-ation in most cases.

% MC = ------------------------------------------ x 100 (wet weight — oven-dry weight)

(oven-dry weight)

% MC = [ ----------------------- — 1 ] x 100

(wet weight)

(oven-dry weight)

SUMMARY • Lumber drying is an easy, profitable manufacturing technique.

• Air-dried lumber must be stacked correctly, protected from the

elements, dried at the correct rate, and dried to the correct MC.

• If proper procedures are used, the lumber will be flat, bright, and free from cracks, checks, and splits.

MEASURING MCMoisture content is a key parameter in wood processing. The MC values are measured daily when operating a dry kiln. Depending on the MC, the temperature may be raised or the relative humidity lowered. In the dried product, any change in MC is accompanied by warping, shrinkage (moisture loss), and swelling (moisture gain). As a result, it is important to measure the MC accurately.

Moisture is measured in two ways: oven-drying and electrically.

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Wood is a valuable material. Although wood is plentiful in the U.S., with annual growth of hardwoods exceeding harvest by 25% for the past 75 years, we need to assure that we will not waste this valuable natural resource as we convert it into lum-ber, and as we convert the lumber into furniture, cabinets, buildings, and other useful products.

A nice size tree has just been felled in the woods. Your plans are to saw as much of the tree as possible into high quality lumber. You want to do this with a minimal amount of waste and, at the same time, you want to maximize the value and useful-ness of the lumber you produce. How do you proceed?

This text was written to provide both the hobbyist and the professional with basic, practical information on how to saw and dry lumber efficiently with minimal loss and downfall. The best operating procedures begin in the woods just after the tree is felled. In Part 1 of this booklet, practical, efficient sawmilling procedures that are dis-cussed and illustrated. Suggested drying procedures are then presented. As a con-clusion to this text, the final section lists sources of additional information on sawing and drying.

All the information presented is based on decades of experience. Therefore, unless there is a good reason not to follow the suggestions presented here, these guidelines will be the most profitable and will waste as little of our resource as possible.

We hope that you find all the information you need to convert our valuable, renewable resource into useful and durable wood products that will last for centuries.

HOW DRY IS DRY ENOUGH?

Achieving Proper Final Moisture Content. . . . . . . . . . . . . . . . . . . 20

ADDITIONAL QUALITY CHARACTERISTICS OF THE DRYING PROCESS

Freedom from Checks and Splits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Freedom from Warp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Freedom from Casehardening (Drying Stresses). . . . . . . . . . . . . . 21

Good Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

High Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Good Machinability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Good Gluability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

MEASURING MC

Oven-drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Electric Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

PART 3 Additional ResourcesSAWING AND GRADING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

DRYING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Gene Wengert

is Professor and

Extension Specialist

Emeritus, Department

of Forest Ecology and

Management, University

of Wisconsin-Madison,

and President of The

Wood Doctor’s Rx, LLC.

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Freedom from Checks and SplitsAll lumber should be end-coated as soon as possible after it is sawn. Good stacking and good control of lumber lengths will help prevent the ends from drying too quickly. High relative humidity at MCs above 40% are critical. Moderate air flows and lower tem-peratures are also important. Above all, the drying rate must be controlled to within narrow limits—the precise rate depends on the species and thickness of the lumber.

Freedom from WarpExcept for cupping, and warp caused by bad stack-ing (such as non-uniform sticker thickness, poor sticker alignment, or non-flat foundations), all warp results because of wood factors and sawmilling pro-cedures. Cup is a result of rewetting partially-dried lumber or over-dried lumber.

Freedom from Casehardening (Drying Stresses)The procedures for proper stress relief (also called conditioning) require the rapid addition of moisture to the lumber surface when the lumber is warm. Often the heat in the steam used for stress relief will increase the kiln temperature above the required level, leading to poor relief. Use of water to cool the steam or cooling the lumber prior to steaming should be considered. Using 180 F air temperature (often called the dry-bulb temperature) is suggested. Note that stress relief will be erratic if the lumber’s MC is not uniform when stress relief begins. Water spray systems can be used in lieu of steam spray. Solar kilns do not require stress relief, as the nighttime high humidities provide freedom from casehardening.

Good ColorBy far, the most critical factor determining lumber’s color (or discoloration) is log freshness. Old logs have 20 times or more risk of developing stain–fun-gal stains, sticker stains, browning, pinking, graying, and so on. Freshly sawn lumber requires low humidi-ties, low temperatures and brisk velocities imme-diately after stacking and until the lumber is under 30% moisture content to control stain. Narrow loads and partially-filled dryers will help. Poor stacking and exposure to rain increase the risk of stain.

High StrengthLow humidities and low dryer temperatures will maximize the strength. Other strength-lowering factors, including bacterial and fungal effects and species effects, are beyond our control.

Good MachinabilityWood that is too wet will fuzz. Wood that is too dry (under 6% MC) will chip, split, and develop other machining defects. Make sure that you monitor the driest pieces of wood in the dryer as well as the wet ones–don’t underestimate the effect of over-drying on machining. Avoid temperatures over 160 F and avoid very low humidities in the drying schedule. (Conditioning or setting the resin at 180 F is accept-able, however.)

Good GluabilityGood gluing requires accurate final MCs. Check for pieces that are too wet (typically over 8.0% MC is too wet), and too dry (under 5.5% MC is too dry). Avoid temperatures over 160 F in the main drying schedule. (Conditioning or setting the resin at 180 F is acceptable, however.)

ADDITIONAL QUALITY CHARACTERISTICS OF THE DRYING PROCESS

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HOW DRY IS DRY ENOUGH?Lumber should be dried to a final MC that is as close to the expected MC that the wood will achieve in use. This guideline is established so as to avoid warping and size change problems in the final product. The MC of wood in-use is related to the relative humidity (RH) that the wood is exposed to; temperature is irrelevant. Different species have the same in-use MC if exposed to the same RH. A special term is used to relate RH to MC in wood; the EMC (equilibrium moisture content) of air is numerically equal to the MC that wood will have when exposed to a given RH. The following tabulation (Table 4) summarizes this relationship.

RULE: The basic rule for drying lumber is that the final MC in the kiln should be within 2% MC of the expected EMC in-use to avoid moisture-related problems. Failure to observe this rule can easily result in manufacturing losses exceeding $1000 per MBF, as well as loss of future sales and customers, and may even result in a law-suit.

As a general rule of thumb, wood shrinks in width or thickness about 1% for every 4% MC change. (This is a general rule, with some variation from species to species. Teak shrinks much less, 1% for 8% MC; oak shrinks much more, 1% for 3% MC.) This means that if a 2-1/2-inch-wide piece of oak loses 3% MC, it will shrink 1% or 0.025 inches! This seems like a small amount of shrinkage, but when gluing, the maximum gap allowed between two pieces of wood is only 0.006 inches. Further, if this oak piece is actually a piece of flooring in a 30-foot wide floor and the entire floor is losing 3% MC, the total shrinkage is 4 inches, which probably is dis-tributed across the floor with objectionable cracks every foot or so.

Table 4 The relationship between humidity, EMC and wood use in North America.

RH MC EMC Condition

% % %

0 0 0 Oven-dry

30 6 6 Lower limit in most homes and offices Lower limit for hardwood furniture and cabinet lumber

36 7 7 Average for hardwood furniture and cabinet lumber

44 8 8 Lower limit for softwood remanufacturing lumber

50 9 9 Upper limit in most homes and offices Upper limit for softwood remanufacturing lumber

65 12 12 Average outside condition, winter and summer Average for softwood construction lumber

80 16 16 Outside condition for coastal areas

Achieving Proper Final Moisture ContentLumber needs to be properly stacked, with sticker openings being uniform in size. Narrow piles (6 feet or under) have more uniform drying than wider piles. In dry kilns, uniformity of temperature, relative humidity, and velocity is required. This uniformity is most critical when the lumber is above 40% MC and also when the lum-ber is under 10% MC. In the kiln, uniform airflow and frequent airflow reversal (two hours) improve uniformity. Equalization should be used for as long as required to achieve the desired uniformity of final MC—it may take longer than 24 hours with some loads. The lumber should be as uniform in thickness and initial MC as possible.

Moisture samples need to be accurate and properly prepared. With as many as 5000 pieces of lumber in a kiln, will just 8 or 10 samples give an adequate picture of the final MC? I suggest 30 samples be taken using a hand-held moisture meter when the kiln is being unloaded to ascertain the correct final MC. When such sam-pling is done, also look for areas in the kiln that are consistently wetter or drier than other areas. Make sure that your moisture measuring technique can detect pieces under 6.0% MC—over-dried lumber is a serious quality problem when machining or gluing.

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Log value is based on the amount and value of lum-ber that will be produced. Based on the results from sawing thousands of hardwood logs, the volume of lumber produced, total and by grade, and the value of the lumber produced from any size and grade log can be estimated. Several examples for red oak logs are given below (Table 1).

Logs that are crooked or short will produce much less high-value lumber than long, straight logs. Further, logs eight feet and shorter will seldom pro-duce much high-quality lumber. Therefore, when bucking a tree into logs, always try to maximize log length, but at the same time, minimize crookedness. These log length bucking decisions are critical for large diameter logs. On the other hand, logs under 16 inches in diameter (small end, inside bark) will seldom produce much high-quality lumber, so length decisions for these smaller logs are not very critical. Incidentally, it is typical that the length of logs is usu-ally about 2 inches over the last full foot; that is, an 8-foot log is really 8' 2", an 11-foot log is 11' 2", and so on.

Once the logs have been manufactured, they need to be handled correctly and sawn promptly. Appreciate that the way the logs are handled influences lumber

PART 1 Sawing the Best Lumber

Table 1 Lumber volume and value from various sized red oak logs

Log Log Log Lumber Diameter Length Grade Selects & Btr No.1C No.2C No.3C Value (inch) (feet) (Bd Ft) (Bd Ft) (Bd Ft) (Bd Ft) ($)

12 10 3 2 11 20 25 32 12 12 2 12 20 23 17 51 14 10 3 4 18 27 30 47 14 12 2 20 33 28 20 76 15 12 2 25 40 31 20 90 16 16 1 90 45 34 13 173 16 16 2 40 64 44 29 140 16 16 3 12 44 53 56 103 20 12 1 124 54 31 18 223 24 12 1 197 81 33 22 338

L U M B E R P R O D U C E D

quality. Logs stored for more than several weeks in warm weather may have already begun to stain, especially at the log ends and wherever the bark has scuffed off. Therefore, prompt sawing of logs in warm weather is essential.

Exposed log ends also are likely to begin drying immediately, resulting in development of stain, end cracks, splits, and checks. It is quite easy for the stain and cracks to penetrate over six inches in just a few months. Further, the dry ends are difficult to saw accurately. The saw wanders excessively in this dry wood, giving erratic lumber thicknesses. Therefore, all logs should be end-coated promptly with a vapor resistant coating (commercial wax coatings, such as Anchor Seal, are very popular) to prevent end checks and reduce the risk of end stain.

In addition to the damage that can be seen, such as end stain and end cracks, stored logs have certain undesirable chemical changes occurring within the wood. Lumber from logs stored several months dur-ing warm weather is at least 10 times more likely to develop cracks and checks in drying. Lumber from stored logs is perhaps 20 times more likely to develop objectionable drying stains, including sticker stain.

LOG QUALITYIt is difficult to produce high-quality lumber from logs that are knotty and crooked. Effective sawing decisions require knowledge of the logs’ quality. So, the first step before sawmilling begins is always to evaluate or grade the logs to estimate their quality. Logs are graded based on their faces. A log has four faces, each face repre-senting 1/4 of the circumference and being the full length of the log (Figure 1). The four faces do not overlap each other. A clear face is free of knots, knot scars on the bark, seams, splits, rot, insect damage, and so on. The clearer the face, the higher the value and the better the lumber that will be produced from the log. Detailed instructions for log grading are available from many state forestry offices, or request Forest Facts #74 (send $2 and a SASE) to the Forestry Department of the University of Wisconsin, 1630 Linden Drive, Madison, WI 53706.

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SAWMILLING QUALITYSawing procedures will influence lumber quality. The following criteria are the technical basis used to develop the suggested sawing procedures discussed in the next section:

• The clearest, knot-free, strongest, most valuable lumber is on the outside of a log. Quality goes down as the lumber is sawn closer to the center (called the pith) of the log.

• Wide, long, clear pieces of lumber are the most valuable. The best hardwood lumber grade guarantees that the lumber is at least 83% clear. Attending a three-day hardwood lumber grad-ing class is well worth the time and expense. Contact the National Hardwood Lumber Association for the dates of a class in your area: (901) 377-1818. Hardwood lumber graders do not need to be certified or licensed.

• Softwood lumber grading is much more complex than hardwood lumber grading, and due to safety concerns, must be done by a certified, licensed grader. Most wood framed buildings are required by the building codes to be built with graded, certified lumber. Check with local building officials for specific requirements and rules in your area.

• Quartersawn lumber (with the rings going from face to face, rather than edge to edge) requires up to 30% longer drying time. Quartersawn lumber has a different grain pattern than flat-sawn, especially in oak, ash, sycamore, beech, and hackberry. This grain may be unwanted by some customers. When sawing quarter-sawn lumber, yields of lumber from the log are reduced, compared to more typical sawing pat-terns. Quartersawn lumber may also shrink up

Face 2

Face 4

Face 3

Face 1

Knot

SeamFIGURE 1to 1/16-inch more (per inch of thickness) than flatsawn lumber during drying, meaning that the green size may have to be increased, further reducing yield.

• Thick lumber requires substantially longer drying time and milder drying conditions. For example: 8/4 requires 2.5 times longer for drying than 4/4 lumber. Therefore, in most cases, saw lumber no thicker than required. Do not saw thick lumber that will be resawn into thinner pieces after dry-ing. If thicker pieces are required, consider saw-ing thinner pieces to glue together later. After sawing, keep them in order, so that after drying you can glue them back together in the same order that they came from the log. In this way, the grain of the small pieces matches very well; it will be difficult to see that the large, thick piece is actually made of several glued-up pieces of wood!

• Lumber that has the rings off center (when look-ing at the end grain of the lumber) will bend to the side more often than not. Therefore, always try to keep the rings centered so that the two edges of the lumber are mirror images.

• Lumber including the pith will warp badly at times and will almost always develop a large split.

• Lumber from crooked logs has high slope of grain (SOG). High SOG also results when the lumber is not sawn parallel to the bark. Lumber with such grain pattern will often warp badly during drying. Lumber with a high SOG has greatly reduced strength as well. Often, the strength is critical when sawing softwood con-struction lumber, so SOG is an important factor to consider when evaluating and sawing logs. Lumber with high SOG also machines poorly, with grain tear-out and raised grain common.

• Softwood lumber intended for construction purposes, with large knots near the edge is not as strong as if the knots were in the center face. Knots on the edges running toward the center of the piece, called spike knots, make the piece of lumber especially weak. Lumber with large knots is weaker than lumber with smaller knots.

• Lumber intended for remanufacturing, especially lumber that will be cut up into smaller pieces for furniture, cabinets, and so on, is most valuable if the knots are near an edge or end, maximizing the size (length and width) of the clear, knot-free areas in the lumber.

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2Initial DryingThe best results are obtained if the lumber is put into a kiln or into controlled drying as quickly as possible. The second best approach is using a shed (a pole shed without walls is ideal) where the lumber is pro-tected from direct rain and sun. Drying sheds require good air flow, so a barn or closed shed is usually too slow. On some species, adding fans to the shed will help develop the lightest, brightest color. By shed-drying before kiln-drying, the annual volume of lum-ber dried in the kiln can be quadrupled, compared to kiln-drying green-from-the-saw.

Air-DryingRemember: Slow drying, such as from slow airflow or high humidity, may result in stain. Fast drying, such as from excessive airflow or low humidities, can result in excessive cracking and splitting. The air-drying process needs to be controlled as closely as possible to avoid extreme conditions that may result in quality loss.

The pile is usually stacked at least 12 inches above the ground to avoid trapping moist air under the pack. The pile should be covered on the top to prevent direct exposure of the lumber to rain and sunshine. More complete instructions on options for quality air-drying are included in Air Drying of Lumber, U.S. Department of Agriculture Handbook No. 402. Although out of print, this handbook is available in most large libraries and can be obtained on inter-library loan from most smaller libraries.

Although air-drying is simple and easy, it is not unusual to have in excess of 10% loss in quality due to the variability and extremes of the weather. Can you afford this? If not, consider shed-drying. (If someone stole 10% of your lumber, wouldn’t you do something about it?) As mentioned, in shed-drying, lumber is placed in an open shed, thereby avoid-ing direct sunlight and rainfall. Drying rates can be regulated by using plastic mesh curtains--pull them closed during hot, dry weather; open them during cool or damp weather. Final moisture is typically over 20% MC.

With either air-drying or shed-drying, the lumber piles need to be placed on a flat foundation with at least 8 inches of clear area underneath. If the air under-neath the piles cannot flow out easily, high humidities will develop under the piles leading to poor drying and a risk of stain. If the foundation is crooked, then warped lumber is likely.

Kiln-DryingThe process referred to as “kiln-drying” involves putting the lumber in a chamber in which the tem-perature, humidity, and air velocity through the lum-ber are controlled. By controlling these three environ-mental variables, the drying rate and the quality of the lumber are controlled. Final moistures are as low as 6% MC.

The smaller producer of kiln-dried lumber has several major choices of equipment. As a broad generaliza-tion, solar-heated dry kilns are best for producing under 25,000 board feet (25 MBF) of lumber annually. Under 2 million board feet (2 MMBF), most operations will find that an electrically operated dehumidification (DH) kiln is best.

Plans for building a solar kiln are available on the Internet (www.woodweb.com). Solar kiln kits are available from Wood-Mizer. Often, a solar kiln will pay for itself after drying just three or four loads of lumber.

Dehumidifier kilns are more expensive than solar, but can provide top quality kiln-dried lumber year-round, regardless of whether the sun is shining or not. Economic aspects of a dehumidifier kiln are dis-cussed in Opportunities for Dehumidification Drying of Hardwood Lumber which is available from the Virginia Forest Products Association (P.O. Box 160, Sandston, VA 23150). The cost of operating a DH kiln can be as high as $75 per MBF. However, the value added by drying is often $300 per MBF. The return on investment with a dehumidifier can be over 20% after taxes.

Dryer operation is discussed in many texts. Three- to five-day short courses are conducted annually throughout the U.S. and Canada. Look for advertisements in trade magazines or contact state forest products specialists.

LUMBER DRYING

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SortingOnce lumber is sawn, it is usually sorted into differ-ent size and value groups in order to facilitate han-dling and to obtain the highest quality.

Lumber is always sorted by species, although sometimes red and white oak will be mixed together.

Lumber is always sorted by thicknesses, as well. It is not advisable to mix thicknesses in the same pile or stack of lumber. If thick and thin lumber is a problem, then run the lumber through a single-headed planer to achieve more uniform thickness.

Lumber is usually sorted by grade or quality clas-sification; often only two sorts are used--valuable lumber (intended for furniture, cabinets, etc.) and the less valuable, industrial grade lumber. This grade sorting is done so that the higher-valued lumber can be treated more carefully than the low-quality lumber. Further, lower-quality lumber is often sold green; it is rarely kiln-dried.

StackingOnce sorted, the green lumber is stacked for drying in order to maintain the highest quality (Figure 9). Lumber is stacked in layers, with all the lumber in each layer being the same thickness. A layer is typi-cally 4 to 6 feet wide. Narrow layers result in faster drying, but also result in piles that can tip over more easily. The length of the layer is the length of the lumber, with the longer pieces being used on the outside edges.

5 '3/4"

1 1/2'

to 2'

stickers

Each layer of lumber is separated from the one above by wooden spacers called stickers. The stick-ers, made of any DRY species of wood, are placed perpendicular to the lumber’s length. The width of the layer is the length of the sticker. The stickers are spaced, starting at one end of the lumber, every 24 inches (although many operations use 12-, 16-, or 18-inch spacings in order to keep the lumber even flatter). The stickers keep the lumber flat and provide space for air flow in the drying process. The stick-ers in one layer must be perfectly vertically aligned (no greater than 1/2 inch variation) with the stickers in layers below and above. A pile or stack is several layers of stickered lumber.

It would be best if the lumber within one stack is all the same length. However, if a few shorter pieces are included (but never more than a 2-foot difference between the shortest and longest), then place the longer pieces on the outside edges of the layer and keep the shorter ones on the inside. The ends of the shorter pieces should always be supported with a sticker; therefore, an extra sticker may have to be used in some layers.

Once stacked, the lumber is placed in a good drying location (even if it will be sold in a few days) where the air can move through the package.

AS SOON AS THE LUMBER IS SAWN . . .

Drying RisksThere are three major risks for lumber that has been freshly sawn:

• The lumber is subject to attack from insects. • The lumber is likely to stain, including mold and mildew stains. • The lumber is likely to crack, if exposed to sun or dry air for a few hours before stacking.

To keep lumber valuable and to avoid wasting this precious natural resource, lumber must be handled correctly from the moment it leaves the saw. If handled improperly at the mill, especially the white woods like maple and pine, can develop stain within 24 hours during warm weather (although often the stain itself doesn’t show up until later). All species can develop value-reducing end splits within several days. Oak and beech are especially susceptible to surface cracks (or checks).

FIGURE 9

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Hardwood Lumber Grades and PricesThere are five basic grades of hardwood lumber (Figure 2)—FAS, Selects (sometimes sold as FAS 1-Face), No.1 Common, No.2 Common, and No.3 Common. Here is a brief summary of the grades:

FAS is a piece of lumber that is at least 83% clear on the worst side of the piece. (Clear means free from rot, pith, shake, wane, knots, stain, and other defects.) The clear area or areas are wide and long; the lumber itself must be at least 6” x 8’.

No.1 Common is at least 67% clear on the worst side of the lumber. The clear areas can be smaller

HARDWOOD SAWING TECHNIQUESThe initial sawing operation is THE KEY to obtaining the highest dollar return and the most useful lumber from every log processed. The operator of the saw, the “sawyer,” must recognize the potential product grade mix that will maximize the value of the log, and then manipulate the log to achieve this maximum value. This requires a “sixth sense” with x-ray vision to visualize what is inside the log before it is sawn.

In order to do an effective job, the sawyer must receive logs that have been properly felled and handled. Logs should not have large protuberances, pronounced crook, kink, or sweep, or jagged ends. Log ends should not be dried out. In short, the sawyer is no magician—the way that logs are harvested, bucked to length, and stored before sawing affects their potential value when sawn into lumber.

To optimize log and product value, the sawyer must also consider how the lumber will be edged and trimmed. If the edging and trimming are not done by the sawyer, then the edgerman, trimmerman and sawyer must develop good communication along with a high degree of skill and judgment. They must act together as a team. They also must operate their equipment safely and efficiently. As a minimum, these people must have a thorough understanding of lumber grades and current lumber values.

FIGURE 2

FAS$9.50

No.1C$6.50

No. 2AC$3.00

No. 3AC$2.25

No. 3BC$1.75

wane

knots

split

worm holesstain

than with FAS. Common lumber can be as short as 4’ and as narrow as 3”.

Selects and FAS 1-Face are No.1 Common pieces that have the better face equivalent to FAS.No.2 Common is 50% clear on the worst side and stain is a defect, but with No.2B Common, stain is not a defect and is ignored.

No.3A Common is 33% clear on the worst side. The lowest grade, No.3B Common, requires only 25% of the piece to be sound, not clear.

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There are many special cases and situa-tions when grading lumber; this is just a general summary. The NHLA publishes an illustrated Inspection School Manual (refer-enced in Part 3 of this report) to help learn the grading rules.

Lumber prices on the retail market vary tre-mendously, even within an individual state. Upper grades of kiln-dried No.1 Common and Better will sell quickly and at very prof-itable prices. The wholesale market prices for lumber vary month to month. Several publications tabulate and publish current prices, including the Hardwood Market Report (Memphis, TN) and the Weekly Hardwood Review (Charlotte, NC). Some typical 2005 prices for kiln-dried lumber (wholesale, FOB mill, gross tally) are given in Table 2. State forestry officials may also publish a newsletter that has ads for lum-ber.

Usually, the green lumber or air-dried lumber prices are lower by $250 or more per MBF. Note that the prices quoted are based on measurement of footage and grade after drying.

For most species, there are poor markets and poor profits for lower grades of lumber, No.2 Common and

Table 2 Typical Prices of Kiln-Dried, 4/4 Hardwood Lumber (12/05) Species FAS No. 1C No. 2C

- - - - - - $ / MBF - - - - - - Ash 1110 780 570 Birch, yellow 1800 1215 805 Cherry 3000 1745 1000 Cottonwood 755 500 250 Maple, hard 2510 1820 1110 Maple, soft 1725 1000 550 Oak, red 1525 875 645 Oak, white 1550 820 570 Walnut 2520 1405 1165 Yellow poplar 885 560 400

Below, especially if sold green. Yet, some lower-grade logs may produce 50% of this low-grade lumber. The most profitable option for lower-grade lumber is to kiln-dry the lumber and then cut the lumber into smaller, clear (or nearly clear) pieces before selling. Although small pieces cannot be graded with stan-dard rules, such pieces are very attractive for hobbyist and small businesses. Typically, these pieces would

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WHY DRY LUMBER?With only a few exceptions, dry lumber is more valuable than undried; kiln-dried is more valuable than air-dried. The advantages of dry lumber include:

• Lumber under 22% moisture content (MC) has no risk of developing fungal stain, decay, rot, or mold.

• Dry lumber weighs over 50% less than wet lumber.

• Dry lumber is over twice as strong and twice as stiff as wet lumber.

• Nails and screws in dry lumber have higher holding power.

• Dry lumber is easier to glue.

• Dry lumber machines better than wet lumber (unless dried under 5% MC).

• Dry wood finishes easier.

• Dry lumber will shrink and swell in-use less than wet lumber that dries in-use.

PART 2 Drying the Best LumberYou have just finished sawing a log into lumber. Several pieces of lumber look fairly clear with a very good grain pattern—these pieces may be potentially quite valuable and useful after they are dried. What needs to be done in order to avoid any quality loss before the lumber is sold green-from-the-saw? Or, what are the next steps in order to produce high-quality kiln-dried lumber ready for manufacturing into cabinets, furniture, millwork, or other items? The following sections review the best procedures for drying lumber.

MOISTURE CONTENTThe amount of water in lumber is measured as a percentage of the lumber’s oven-dry weight. For example, in a piece of lumber weighing 10 pounds, if there are 4 pounds of water and 6 pounds of dry wood, the moisture content is 67%. This value is calculated as the weight of water divided by the oven-dry weight, times 100 to convert to percentage. So, in this example: 4 ÷ 6 x 100 = 67%.

WATER IN WOODThe living tree contains a great deal of moisture—this moisture is the “life blood” of the tree, conduct-ing nutrients from the roots to the leaves, where the process of photosynthesis takes place. The water content, incidentally, remains the same year-round—the sap is not up in the summer and down in the winter.

In the living tree, wood typically has a moisture content of 75% or higher. (One-thousand board feet of oak can weigh 4900 pounds. At 75% MC, there are 2100 pounds of water and 2800 pounds of wood.) In order to use lumber for furniture, cabi-nets, millwork, and similar indoor uses, almost all of the water must be removed—the removal process is called “drying.” For interior uses, the moisture content should be 7%, which is equivalent to the MC that wood will achieve in a relative humidity of 38% RH—the typical interior average RH for most homes and offices. (This means, using the previous example, that all but 196 pounds of water must be removed before the oak can be used.)

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3 - Cant SawingThe log is sawn much like grade sawing, but the center of the log, which may be a piece with dimensions of 7” x 9”, 10” x 10”, or so, is either sent to another machine for further processing or is sold as a large (and heavy) timber (Figure 5). Cant sawing maximizes sawmill production (board feet per day) and is commonly used throughout the hardwood industry in medium and large size mills. It is used primarily on medium- and low-quality logs where the lumber from the center of the log will not be very high in value. With cant sawing, valuable time and effort is not wasted manufacturing low-grade, low-value lumber.

Face 4

Face 2

Face 3

Face 1

FIGURE 3

Face 2 Face 3

FIGURE 4

Face 3

Face 3

Face 3

Face 3CANT

FIGURE 5

Hardwood Sawing PatternsThe actual sawing pattern used (sawing pattern includes lumber thickness, log rotation, and taper offset) depends on many factors, including species, log quality, log size, mill design, sawing equipment, and lumber grade values. There are three basic sawing options for standard lumber; however, for quartersawn lumber, see Figure 5 and the accompanying discussion.

1 - Grade Sawing (or Around Sawing)The log is sawn and turned to a new face, sawn and turned again, perhaps turned as many as five times (Figure 3). This is the best (financially) for medium- and high-quality logs, even though it may be difficult to turn a log on some mills and daily production vol-ume may be lower. Hydraulic log turning is much bet-ter than “arm-strong” power!

2 - Live Sawing (or Through-and-Through Sawing)The log is sawn about halfway through on the opening face and then turned once to the opposite face and sawn on that face until finished (Figure 4). Although this can be the easiest and quickest sawing method, live sawing means that every piece of lumber must be edged—for highest value, many pieces will be ripped into two or three pieces as well. Further, live-sawn lumber is quite wide and heavy, is lower in grade, and has a lot of quartersawn grain. Live-sawn lumber often has excessive warp in the drying process. In short, live-sawing is usually best only for lower quality logs where the above disadvantages are not important.

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Opening FaceOf all the decisions facing the sawyer, the decision as to which face to open first (that is, where to begin sawing) is the most important. (A log is divided into four faces, each face being of the log’s circumference, full length, and not overlapping another face. Once the slab is removed from a face, the flat surface is the face.) The choice of the opening face determines the location of all the other faces. Initially, a log could be sawn in several million different ways; only a hundred of these ways are most profitable! Once the opening face is cho-sen, there are now only several thousand decisions for the sawyer to make.

In grade or cant sawing methods, there are two basic opening face options—

Option #1: The poorest face of the four faces is opened first without any taper set. (Taper set refers to the process of raising or skewing the log so that the saw cuts parallel to the bark on the face being sawn.) Because this is the poorest face, this means that short lumber and potentially large slabs will come from the very low-value part of the log. With no taper setting, it means that the opposite face, which is a better face, will be sawn parallel to the bark when the log is turned without having to use taper sets on that face. As a result, higher-grade lumber which comes from this better face will be full length.

Option #2: The best face on the log is opened first with full taper. Full taper means that the log is raised or skewed as much as needed so that the first cut runs parallel to the bark. This means, as in Option #1, that the higher grade face will be sawn parallel to the bark and will produce full-length lumber.

The end results of either method will be nearly the same, but there is one advantage to Option #2. It is easier to position the log (i.e., rotate it slightly) so that the opening face is as clear (free of defects) as possible. With Option #1, the back side (or opposite side) of the log is the better face, but fine-tuning the rotation is diffi-cult as the back side cannot be seen easily in a production situation. When sawing a high-grade log with many clear areas and faces, the difference between Option #1 and #2 is small. However, in a lower-grade log with limited clearness, Option #2 will often prove to be better.

Face 2

Face 4

Face 3

Face 1

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1SUMMARY • Converting logs into lumber can be quite profitable and

rewarding if done properly and safely.

• Log storage should be as short as possible.

• Logs should be end-coated.

• Logs should be opened on the worst face without taper, or the best face with taper.

• Opening face widths should be 4-1/2 or 6-1/2 inches for hardwoods, and 6 inches for softwoods, typically.

• Logs should be turned whenever an adjacent face promises to have higher grade lumber.

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Step 1. Position the log so that the smaller defects will show up in the center of the lumber, where such defects are less serious with respect to strength. When possible, consider putting all the knots or other defects into one face leaving the other faces clear. However, for construction lumber, usually a clear piece is no more valuable than a piece with a few small knots. On the other hand, large knots or defects will always be strength-reducing.

Step 2. Choose the worst face of the log and begin sawing on this worst face, producing short pieces of lumber. Do not taper saw (or offset) the log. Rather, take any and all taper out of the log on this worst face. The first piece will be low-grade and should be the shortest piece that you can market. Long and narrow is better than short and wide in most cases.

Step 3. After the worst side has a flat surface from end to end (and maybe one or two pieces of lumber have been cut if the log is quite large), then go to the opposite face, sawing parallel to the bark, producing a full-length piece of lumber. Turning to the opposite face reduces the workload when edging the pieces, meaning less warp in drying and wider pieces will be produced, compared to going to an adjacent face for the second face.

On a good face, the opening width should typically be 6 inches, which means that the first piece of lumber will be 6 inches wide and full-length. On a smaller log (under 13 inches in diameter), the production of 4-inch width for the first piece is probably better.

A butt log will have less defect in the center and so should probably not be converted into a large timber, but should be sawn entirely into lumber.

Step 4. Always turn the log from the present face to another face if the grade of lumber on the adjacent faces would be higher than the piece produced on the existing face.

Step 5. Sweepy logs. (Figure 8) Saw the ears off in one cut, unless there is useable lumber in the ears. Then rotate to the belly, perhaps producing some short pieces of lumber. Sweepy, low-grade logs are a waste of time.

SOFTWOOD SAWING TECHNIQUESMany of the techniques used for hardwood log sawing apply to softwoods as well. A few differences are highlighted in the following two sections.

Sweepy Log

FIGURE 8

Sawing Softwood Logs Into Construction LumberThe following outline indicates the best way (most economical way) to saw softwood logs most of the time. Certainly, safety concerns must override volume or value concerns.

Sawing Softwood Logs into Boards and Lumber for RemanufacturingThe log-sawing procedures are similar to the construction lumber sawing, except for the opening face size. On a good face, the opening width should typically be 6-1/2 inches, which means that the first piece of lumber will be 6-1/2 inches wide and full-length. On a smaller log (under 13 inches in diameter), the production of 4-1/2 inch width for the first piece is probably better. The opening piece should probably be 4/4 thick, rather than 8/4, if there is a market for 4/4. A butt log will have less defect in the center and so should probably not be converted into a large timber, but should be sawn entirely into lumber.

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1General RecommendationsHIGH-QUALITY BUTT LOGS (a butt log is thebottom log of the tree) will yield the most valuable lumber. Therefore, when sawing such logs, the saw-yer must determine which mix of thicknesses will maximize the volume and value recovery for each log face. As the price of lumber increases with thick-ness—for example, 4/4, FAS, green hard maple sells at $1060 per MBF wholesale, while 8/4 sells at $1210—and because thicker lumber has less saw-dust and higher lumber yields per log (as much as 10% more lumber for a log sawn into 8/4 versus 4/4), this decision can have a large impact on profits. However, if, when producing thicker lumber, the grade of the lumber drops to No. 2 Common or lower, even though the better side is clear or nearly clear, there would be substantial loss, as the market for thick, low-grade lumber is poor. The sawyer must try to switch to 4/4 or 5/4 thickness before the grade drops. (Remember—you do not make any money sawing lumber until the lumber is sold. For this reason, the grades, value, and useful-ness of the lumber produced is critical for profitable operations.)

From these high-quality logs, production of large timber and railway ties from the center would often be ill-advised, as these large cants will often have substantial middle- and high-grade lum-ber. In other words, cant value would be less than lumber value.

For these high-grade logs, grade sawing is recom-mended. In fact, taper-sawing (skewing the log on the carriage so that lumber is sawn parallel to the bark) is recommended for all “good” faces. This will result in putting clear wood into full-length, more valuable pieces of lumber and will avoid cutting clear wood into short pieces. When the lower-grade por-tion of the log is reached, then any taper would be taken out of the log; that is, a wedge-shaped piece would be cut to square the remaining cant and mini-mize edging of theremaining pieces.

MEDIUM-QUALITY LOGS offer considerable challenge to the sawyer because they contain large volumes of No. 1 Common and Better lumber. It takes skill to recover this valuable lumber. Grade sawing, which means rotating the log from one face to the next, will provide the highest value; these rota-tion decisions are critical decisions.

Specific Sawing Suggestions(NOTE: All suggestion here must factor in safety requirements first!)

To begin, the sawyer (using Option #1) selects the worst face and opens it without taper. Do not saw the opening, low-grade face very long before rota-tion. With a small log, the worst face could have just a slab removed (that is, just one cut full-length), or a slab and a short board before the log is rotated to the opposite face. With a larger log, several short pieces of lumber could be removed, and at times even a full-length piece could be sawn.

Alternately, the sawyer (using Option #2) selects the best face and opens it with full taper. This face is then sawn heavily before the log is rotated to another face.

POOR QUALITY, SOUND LOGS which will produce no higher than No. 2 Common lumber should be sawn as quickly as possible. In other words, there is little or no profit in these logs, so they should be removed from the sawmill as quickly as possible. Any sawing method is acceptable, so long as the log can be sawn quickly and safely. Most often the log would be cant-sawn (often financially the best) or live-sawn. Every minute of sawing time carries a price ticket, so it is important to achieve the compro-mise between sawing cost (perhaps $100 per MBF) and lumber value. Log-turning should be kept to an absolute minimum for low-value logs.

UNSOUND LOGS should never be purchased in the first place as profit is nonexistent and safety risk can be high. It is a better investment to spend money for higher-quality logs which have good profit potential than to purchase low-grade, unsound, non-profit logs.

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Log RotationLumber is sawn off of one face until the sawyer expects that the next piece of lumber to be sawn will be lower in grade than if lumber were sawn off of the adjacent faces. (Exception: A “worst face” must be sawn deep enough to achieve a satisfactory flat surface before turning the log to another face.) When the grade estimate for the present face is lower than either of the adjacent faces, the log is rotated to a new face. (In other words, a good face is sawn deep-ly; a poor face may only be slabbed or have a slab and one board removed.) This rule for rotation applies to all faces and throughout the sawing process.

It is preferred that the log is rotated 180 degrees from the opening face to the second face. As many mills do not use this rotation pattern, even though it has been standard since 1956, it is necessary to dis-cuss the advantages in more detail.

Consider a 24-inch log (it works for any size log, however). The 180-degree rotation results in 8 pieces needing edging, while the poor method (always rotating to an adjacent face) results in 13 pieces that need to be edged. This alone is quite significant in terms of work load for a small sawmiller. The 180- degree rotation method produces more wide pieces, which are usually more valuable (Table 3). In addition, there are 8 pieces in the adjacent method that have rings that are not centered, edge to edge, which means that these pieces are likely to develop side-bend in drying. Further, if this is a species like walnut or red oak with a nar-row band of sapwood, in the 180-degree method, 10 pieces will have sapwood in them; in the adja-cent method, 13 pieces. Sapwood causes drying problems (checks easier for oak) and also color problems for some customers. The effect of log stress or “spring” is minimized with 180 rotation, as well.

We are aware that rotating to an adjacent face may be easier, but the economic and safety benefits strongly encourage 180-degree rotation. After the first two opposite faces are sawn, the third and fourth face are sawn. When beginning on the third and fourth faces (which are opposite each other), the poorer face of the two is opened first with no taper, if this third face is not very high quality. However, a high-quality face should probably always be opened parallel to the bark, which means that taper-setting is required.

Opening Face SizesThe width of the opening face, or width of the slab-bing cut, on all of the four faces is critical.

Good Grade FaceIf the sawyer believes that the grade of the first piece

of lumber that will be sawn is high grade (Select, FAS 1-Face, or FAS), then the minimum width of the open-ing face (that is, the minimum width of wood measured on the log) should be 6-1/2 inches. This width is con-sidered along the entire length of the log. (Why do we use 6-1/2 inch opening size? Because FAS 1-Face and FAS lumber must be at least 6 inches wide. To allow for shrinkage and perhaps a little light edging at times, plus because a little extra width can help the lumber achieve the desired grade, 6-1/2-inch width is recom-mended rather than 6.0 inches. Although Selects can be 4- or 5-inches wide, the wane restrictions on these pieces are so severe that they are not worth manufac-turing intentionally.)

Lower Grade FaceIf the sawyer believes that the best grade of lumber that can be produced is No. 1 Common or lower, then the minimum opening face width should be 4-1/2 inches. This opening width is only considered along a 4-foot length of the log, assuming that the short-est piece of lumber that can be sold is four feet long. (Adjust this length for the shortest piece that is sold at your mill.)

Sweepy Logs Better quality logs with pronounced sweep should be sawn initially with the “belly” to the saw or with the “ears” to the saw, rather than by looking for clear faces. The ears are typically removed in one or two passes, providing a flat surface along the entire log length. The belly can be sawn in several passes, often producing some short, clear pieces of lumber. Once the log is squared, then the remaining two faces are sawn, most often turning the log only once, but using standard log turning rules and procedures mentioned previously. (Hint: When edging lumber from the belly, long and narrow is better than fat and short.)

Poor-quality logs with pronounced sweep should never reach the sawmill if the purpose of the lumber is for profit.

Table 3 The size of pieces of lumber sawn with 180 degree rotation and with adjacent from a 24-inch diameter log.

Width of Lumber Number of Pieces

180 Degree Adjacent

20" 2 1 17" 2 1 15" 0 1 14" 2 3 13" 0 2 11" 10 8 10" 2 1

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1QuartersawingQuartersawn lumber offers several advantages compared to flatsawn lumber. Quartersawn lumber typically has heavy ray fleck, which some people find appealing. Quartersawn has about half of the shrinkage in width as flatsawn (3% instead of 6% when drying). Quartersawn lumber dries flatter and has less risk of checking dur-ing drying. Quartersawn lumber is more stable in an environment with varying humidity. Quartersawn lumber wears more evenly when used as flooring.

On the other hand, producing quartersawn lumber often results in 20% lower yields from the log. Lumber production rates are much lower as well. Quartersawn lumber requires 15% or so longer drying times. Quartersawn lumber shrinks twice as much in thickness as flatsawn. Quartersawn lumber will have spike knots, compared to the circular knots in flatsawn lumber; spike knots greatly reduce the strength of lumber.

Sawing procedures are illustrated in Figure 6 for large logs and Figure 7 for smaller logs. As always, sawing must be done with safety in mind.

6 1/2"

for a Good Log and Full Length

Opening Face

4 1/2"

for a Lower Quality Log

and 4' Long

4 '

Opening Face

FIGURE 6

FIGURE 7

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Log RotationLumber is sawn off of one face until the sawyer expects that the next piece of lumber to be sawn will be lower in grade than if lumber were sawn off of the adjacent faces. (Exception: A “worst face” must be sawn deep enough to achieve a satisfactory flat surface before turning the log to another face.) When the grade estimate for the present face is lower than either of the adjacent faces, the log is rotated to a new face. (In other words, a good face is sawn deep-ly; a poor face may only be slabbed or have a slab and one board removed.) This rule for rotation applies to all faces and throughout the sawing process.

It is preferred that the log is rotated 180 degrees from the opening face to the second face. As many mills do not use this rotation pattern, even though it has been standard since 1956, it is necessary to dis-cuss the advantages in more detail.

Consider a 24-inch log (it works for any size log, however). The 180-degree rotation results in 8 pieces needing edging, while the poor method (always rotating to an adjacent face) results in 13 pieces that need to be edged. This alone is quite significant in terms of work load for a small sawmiller. The 180- degree rotation method produces more wide pieces, which are usually more valuable (Table 3). In addition, there are 8 pieces in the adjacent method that have rings that are not centered, edge to edge, which means that these pieces are likely to develop side-bend in drying. Further, if this is a species like walnut or red oak with a nar-row band of sapwood, in the 180-degree method, 10 pieces will have sapwood in them; in the adja-cent method, 13 pieces. Sapwood causes drying problems (checks easier for oak) and also color problems for some customers. The effect of log stress or “spring” is minimized with 180 rotation, as well.

We are aware that rotating to an adjacent face may be easier, but the economic and safety benefits strongly encourage 180-degree rotation. After the first two opposite faces are sawn, the third and fourth face are sawn. When beginning on the third and fourth faces (which are opposite each other), the poorer face of the two is opened first with no taper, if this third face is not very high quality. However, a high-quality face should probably always be opened parallel to the bark, which means that taper-setting is required.

Opening Face SizesThe width of the opening face, or width of the slab-bing cut, on all of the four faces is critical.

Good Grade FaceIf the sawyer believes that the grade of the first piece

of lumber that will be sawn is high grade (Select, FAS 1-Face, or FAS), then the minimum width of the open-ing face (that is, the minimum width of wood measured on the log) should be 6-1/2 inches. This width is con-sidered along the entire length of the log. (Why do we use 6-1/2 inch opening size? Because FAS 1-Face and FAS lumber must be at least 6 inches wide. To allow for shrinkage and perhaps a little light edging at times, plus because a little extra width can help the lumber achieve the desired grade, 6-1/2-inch width is recom-mended rather than 6.0 inches. Although Selects can be 4- or 5-inches wide, the wane restrictions on these pieces are so severe that they are not worth manufac-turing intentionally.)

Lower Grade FaceIf the sawyer believes that the best grade of lumber that can be produced is No. 1 Common or lower, then the minimum opening face width should be 4-1/2 inches. This opening width is only considered along a 4-foot length of the log, assuming that the short-est piece of lumber that can be sold is four feet long. (Adjust this length for the shortest piece that is sold at your mill.)

Sweepy Logs Better quality logs with pronounced sweep should be sawn initially with the “belly” to the saw or with the “ears” to the saw, rather than by looking for clear faces. The ears are typically removed in one or two passes, providing a flat surface along the entire log length. The belly can be sawn in several passes, often producing some short, clear pieces of lumber. Once the log is squared, then the remaining two faces are sawn, most often turning the log only once, but using standard log turning rules and procedures mentioned previously. (Hint: When edging lumber from the belly, long and narrow is better than fat and short.)

Poor-quality logs with pronounced sweep should never reach the sawmill if the purpose of the lumber is for profit.

Table 3 The size of pieces of lumber sawn with 180 degree rotation and with adjacent from a 24-inch diameter log.

Width of Lumber Number of Pieces

180 Degree Adjacent

20" 2 1 17" 2 1 15" 0 1 14" 2 3 13" 0 2 11" 10 8 10" 2 1

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1QuartersawingQuartersawn lumber offers several advantages compared to flatsawn lumber. Quartersawn lumber typically has heavy ray fleck, which some people find appealing. Quartersawn has about half of the shrinkage in width as flatsawn (3% instead of 6% when drying). Quartersawn lumber dries flatter and has less risk of checking dur-ing drying. Quartersawn lumber is more stable in an environment with varying humidity. Quartersawn lumber wears more evenly when used as flooring.

On the other hand, producing quartersawn lumber often results in 20% lower yields from the log. Lumber production rates are much lower as well. Quartersawn lumber requires 15% or so longer drying times. Quartersawn lumber shrinks twice as much in thickness as flatsawn. Quartersawn lumber will have spike knots, compared to the circular knots in flatsawn lumber; spike knots greatly reduce the strength of lumber.

Sawing procedures are illustrated in Figure 6 for large logs and Figure 7 for smaller logs. As always, sawing must be done with safety in mind.

6 1/2"

for a Good Log and Full Length

Opening Face

4 1/2"

for a Lower Quality Log

and 4' Long

4 '

Opening Face

FIGURE 6

FIGURE 7

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Step 1. Position the log so that the smaller defects will show up in the center of the lumber, where such defects are less serious with respect to strength. When possible, consider putting all the knots or other defects into one face leaving the other faces clear. However, for construction lumber, usually a clear piece is no more valuable than a piece with a few small knots. On the other hand, large knots or defects will always be strength-reducing.

Step 2. Choose the worst face of the log and begin sawing on this worst face, producing short pieces of lumber. Do not taper saw (or offset) the log. Rather, take any and all taper out of the log on this worst face. The first piece will be low-grade and should be the shortest piece that you can market. Long and narrow is better than short and wide in most cases.

Step 3. After the worst side has a flat surface from end to end (and maybe one or two pieces of lumber have been cut if the log is quite large), then go to the opposite face, sawing parallel to the bark, producing a full-length piece of lumber. Turning to the opposite face reduces the workload when edging the pieces, meaning less warp in drying and wider pieces will be produced, compared to going to an adjacent face for the second face.

On a good face, the opening width should typically be 6 inches, which means that the first piece of lumber will be 6 inches wide and full-length. On a smaller log (under 13 inches in diameter), the production of 4-inch width for the first piece is probably better.

A butt log will have less defect in the center and so should probably not be converted into a large timber, but should be sawn entirely into lumber.

Step 4. Always turn the log from the present face to another face if the grade of lumber on the adjacent faces would be higher than the piece produced on the existing face.

Step 5. Sweepy logs. (Figure 8) Saw the ears off in one cut, unless there is useable lumber in the ears. Then rotate to the belly, perhaps producing some short pieces of lumber. Sweepy, low-grade logs are a waste of time.

SOFTWOOD SAWING TECHNIQUESMany of the techniques used for hardwood log sawing apply to softwoods as well. A few differences are highlighted in the following two sections.

Sweepy Log

FIGURE 8

Sawing Softwood Logs Into Construction LumberThe following outline indicates the best way (most economical way) to saw softwood logs most of the time. Certainly, safety concerns must override volume or value concerns.

Sawing Softwood Logs into Boards and Lumber for RemanufacturingThe log-sawing procedures are similar to the construction lumber sawing, except for the opening face size. On a good face, the opening width should typically be 6-1/2 inches, which means that the first piece of lumber will be 6-1/2 inches wide and full-length. On a smaller log (under 13 inches in diameter), the production of 4-1/2 inch width for the first piece is probably better. The opening piece should probably be 4/4 thick, rather than 8/4, if there is a market for 4/4. A butt log will have less defect in the center and so should probably not be converted into a large timber, but should be sawn entirely into lumber.

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1General RecommendationsHIGH-QUALITY BUTT LOGS (a butt log is thebottom log of the tree) will yield the most valuable lumber. Therefore, when sawing such logs, the saw-yer must determine which mix of thicknesses will maximize the volume and value recovery for each log face. As the price of lumber increases with thick-ness—for example, 4/4, FAS, green hard maple sells at $1060 per MBF wholesale, while 8/4 sells at $1210—and because thicker lumber has less saw-dust and higher lumber yields per log (as much as 10% more lumber for a log sawn into 8/4 versus 4/4), this decision can have a large impact on profits. However, if, when producing thicker lumber, the grade of the lumber drops to No. 2 Common or lower, even though the better side is clear or nearly clear, there would be substantial loss, as the market for thick, low-grade lumber is poor. The sawyer must try to switch to 4/4 or 5/4 thickness before the grade drops. (Remember—you do not make any money sawing lumber until the lumber is sold. For this reason, the grades, value, and useful-ness of the lumber produced is critical for profitable operations.)

From these high-quality logs, production of large timber and railway ties from the center would often be ill-advised, as these large cants will often have substantial middle- and high-grade lum-ber. In other words, cant value would be less than lumber value.

For these high-grade logs, grade sawing is recom-mended. In fact, taper-sawing (skewing the log on the carriage so that lumber is sawn parallel to the bark) is recommended for all “good” faces. This will result in putting clear wood into full-length, more valuable pieces of lumber and will avoid cutting clear wood into short pieces. When the lower-grade por-tion of the log is reached, then any taper would be taken out of the log; that is, a wedge-shaped piece would be cut to square the remaining cant and mini-mize edging of theremaining pieces.

MEDIUM-QUALITY LOGS offer considerable challenge to the sawyer because they contain large volumes of No. 1 Common and Better lumber. It takes skill to recover this valuable lumber. Grade sawing, which means rotating the log from one face to the next, will provide the highest value; these rota-tion decisions are critical decisions.

Specific Sawing Suggestions(NOTE: All suggestion here must factor in safety requirements first!)

To begin, the sawyer (using Option #1) selects the worst face and opens it without taper. Do not saw the opening, low-grade face very long before rota-tion. With a small log, the worst face could have just a slab removed (that is, just one cut full-length), or a slab and a short board before the log is rotated to the opposite face. With a larger log, several short pieces of lumber could be removed, and at times even a full-length piece could be sawn.

Alternately, the sawyer (using Option #2) selects the best face and opens it with full taper. This face is then sawn heavily before the log is rotated to another face.

POOR QUALITY, SOUND LOGS which will produce no higher than No. 2 Common lumber should be sawn as quickly as possible. In other words, there is little or no profit in these logs, so they should be removed from the sawmill as quickly as possible. Any sawing method is acceptable, so long as the log can be sawn quickly and safely. Most often the log would be cant-sawn (often financially the best) or live-sawn. Every minute of sawing time carries a price ticket, so it is important to achieve the compro-mise between sawing cost (perhaps $100 per MBF) and lumber value. Log-turning should be kept to an absolute minimum for low-value logs.

UNSOUND LOGS should never be purchased in the first place as profit is nonexistent and safety risk can be high. It is a better investment to spend money for higher-quality logs which have good profit potential than to purchase low-grade, unsound, non-profit logs.

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Opening FaceOf all the decisions facing the sawyer, the decision as to which face to open first (that is, where to begin sawing) is the most important. (A log is divided into four faces, each face being of the log’s circumference, full length, and not overlapping another face. Once the slab is removed from a face, the flat surface is the face.) The choice of the opening face determines the location of all the other faces. Initially, a log could be sawn in several million different ways; only a hundred of these ways are most profitable! Once the opening face is cho-sen, there are now only several thousand decisions for the sawyer to make.

In grade or cant sawing methods, there are two basic opening face options—

Option #1: The poorest face of the four faces is opened first without any taper set. (Taper set refers to the process of raising or skewing the log so that the saw cuts parallel to the bark on the face being sawn.) Because this is the poorest face, this means that short lumber and potentially large slabs will come from the very low-value part of the log. With no taper setting, it means that the opposite face, which is a better face, will be sawn parallel to the bark when the log is turned without having to use taper sets on that face. As a result, higher-grade lumber which comes from this better face will be full length.

Option #2: The best face on the log is opened first with full taper. Full taper means that the log is raised or skewed as much as needed so that the first cut runs parallel to the bark. This means, as in Option #1, that the higher grade face will be sawn parallel to the bark and will produce full-length lumber.

The end results of either method will be nearly the same, but there is one advantage to Option #2. It is easier to position the log (i.e., rotate it slightly) so that the opening face is as clear (free of defects) as possible. With Option #1, the back side (or opposite side) of the log is the better face, but fine-tuning the rotation is diffi-cult as the back side cannot be seen easily in a production situation. When sawing a high-grade log with many clear areas and faces, the difference between Option #1 and #2 is small. However, in a lower-grade log with limited clearness, Option #2 will often prove to be better.

Face 2

Face 4

Face 3

Face 1

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1SUMMARY • Converting logs into lumber can be quite profitable and

rewarding if done properly and safely.

• Log storage should be as short as possible.

• Logs should be end-coated.

• Logs should be opened on the worst face without taper, or the best face with taper.

• Opening face widths should be 4-1/2 or 6-1/2 inches for hardwoods, and 6 inches for softwoods, typically.

• Logs should be turned whenever an adjacent face promises to have higher grade lumber.

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3 - Cant SawingThe log is sawn much like grade sawing, but the center of the log, which may be a piece with dimensions of 7” x 9”, 10” x 10”, or so, is either sent to another machine for further processing or is sold as a large (and heavy) timber (Figure 5). Cant sawing maximizes sawmill production (board feet per day) and is commonly used throughout the hardwood industry in medium and large size mills. It is used primarily on medium- and low-quality logs where the lumber from the center of the log will not be very high in value. With cant sawing, valuable time and effort is not wasted manufacturing low-grade, low-value lumber.

Face 4

Face 2

Face 3

Face 1

FIGURE 3

Face 2 Face 3

FIGURE 4

Face 3

Face 3

Face 3

Face 3CANT

FIGURE 5

Hardwood Sawing PatternsThe actual sawing pattern used (sawing pattern includes lumber thickness, log rotation, and taper offset) depends on many factors, including species, log quality, log size, mill design, sawing equipment, and lumber grade values. There are three basic sawing options for standard lumber; however, for quartersawn lumber, see Figure 5 and the accompanying discussion.

1 - Grade Sawing (or Around Sawing)The log is sawn and turned to a new face, sawn and turned again, perhaps turned as many as five times (Figure 3). This is the best (financially) for medium- and high-quality logs, even though it may be difficult to turn a log on some mills and daily production vol-ume may be lower. Hydraulic log turning is much bet-ter than “arm-strong” power!

2 - Live Sawing (or Through-and-Through Sawing)The log is sawn about halfway through on the opening face and then turned once to the opposite face and sawn on that face until finished (Figure 4). Although this can be the easiest and quickest sawing method, live sawing means that every piece of lumber must be edged—for highest value, many pieces will be ripped into two or three pieces as well. Further, live-sawn lumber is quite wide and heavy, is lower in grade, and has a lot of quartersawn grain. Live-sawn lumber often has excessive warp in the drying process. In short, live-sawing is usually best only for lower quality logs where the above disadvantages are not important.

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There are many special cases and situa-tions when grading lumber; this is just a general summary. The NHLA publishes an illustrated Inspection School Manual (refer-enced in Part 3 of this report) to help learn the grading rules.

Lumber prices on the retail market vary tre-mendously, even within an individual state. Upper grades of kiln-dried No.1 Common and Better will sell quickly and at very prof-itable prices. The wholesale market prices for lumber vary month to month. Several publications tabulate and publish current prices, including the Hardwood Market Report (Memphis, TN) and the Weekly Hardwood Review (Charlotte, NC). Some typical 2005 prices for kiln-dried lumber (wholesale, FOB mill, gross tally) are given in Table 2. State forestry officials may also publish a newsletter that has ads for lum-ber.

Usually, the green lumber or air-dried lumber prices are lower by $250 or more per MBF. Note that the prices quoted are based on measurement of footage and grade after drying.

For most species, there are poor markets and poor profits for lower grades of lumber, No.2 Common and

Table 2 Typical Prices of Kiln-Dried, 4/4 Hardwood Lumber (12/05) Species FAS No. 1C No. 2C

- - - - - - $ / MBF - - - - - - Ash 1110 780 570 Birch, yellow 1800 1215 805 Cherry 3000 1745 1000 Cottonwood 755 500 250 Maple, hard 2510 1820 1110 Maple, soft 1725 1000 550 Oak, red 1525 875 645 Oak, white 1550 820 570 Walnut 2520 1405 1165 Yellow poplar 885 560 400

Below, especially if sold green. Yet, some lower-grade logs may produce 50% of this low-grade lumber. The most profitable option for lower-grade lumber is to kiln-dry the lumber and then cut the lumber into smaller, clear (or nearly clear) pieces before selling. Although small pieces cannot be graded with stan-dard rules, such pieces are very attractive for hobbyist and small businesses. Typically, these pieces would

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WHY DRY LUMBER?With only a few exceptions, dry lumber is more valuable than undried; kiln-dried is more valuable than air-dried. The advantages of dry lumber include:

• Lumber under 22% moisture content (MC) has no risk of developing fungal stain, decay, rot, or mold.

• Dry lumber weighs over 50% less than wet lumber.

• Dry lumber is over twice as strong and twice as stiff as wet lumber.

• Nails and screws in dry lumber have higher holding power.

• Dry lumber is easier to glue.

• Dry lumber machines better than wet lumber (unless dried under 5% MC).

• Dry wood finishes easier.

• Dry lumber will shrink and swell in-use less than wet lumber that dries in-use.

PART 2 Drying the Best LumberYou have just finished sawing a log into lumber. Several pieces of lumber look fairly clear with a very good grain pattern—these pieces may be potentially quite valuable and useful after they are dried. What needs to be done in order to avoid any quality loss before the lumber is sold green-from-the-saw? Or, what are the next steps in order to produce high-quality kiln-dried lumber ready for manufacturing into cabinets, furniture, millwork, or other items? The following sections review the best procedures for drying lumber.

MOISTURE CONTENTThe amount of water in lumber is measured as a percentage of the lumber’s oven-dry weight. For example, in a piece of lumber weighing 10 pounds, if there are 4 pounds of water and 6 pounds of dry wood, the moisture content is 67%. This value is calculated as the weight of water divided by the oven-dry weight, times 100 to convert to percentage. So, in this example: 4 ÷ 6 x 100 = 67%.

WATER IN WOODThe living tree contains a great deal of moisture—this moisture is the “life blood” of the tree, conduct-ing nutrients from the roots to the leaves, where the process of photosynthesis takes place. The water content, incidentally, remains the same year-round—the sap is not up in the summer and down in the winter.

In the living tree, wood typically has a moisture content of 75% or higher. (One-thousand board feet of oak can weigh 4900 pounds. At 75% MC, there are 2100 pounds of water and 2800 pounds of wood.) In order to use lumber for furniture, cabi-nets, millwork, and similar indoor uses, almost all of the water must be removed—the removal process is called “drying.” For interior uses, the moisture content should be 7%, which is equivalent to the MC that wood will achieve in a relative humidity of 38% RH—the typical interior average RH for most homes and offices. (This means, using the previous example, that all but 196 pounds of water must be removed before the oak can be used.)

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SortingOnce lumber is sawn, it is usually sorted into differ-ent size and value groups in order to facilitate han-dling and to obtain the highest quality.

Lumber is always sorted by species, although sometimes red and white oak will be mixed together.

Lumber is always sorted by thicknesses, as well. It is not advisable to mix thicknesses in the same pile or stack of lumber. If thick and thin lumber is a problem, then run the lumber through a single-headed planer to achieve more uniform thickness.

Lumber is usually sorted by grade or quality clas-sification; often only two sorts are used--valuable lumber (intended for furniture, cabinets, etc.) and the less valuable, industrial grade lumber. This grade sorting is done so that the higher-valued lumber can be treated more carefully than the low-quality lumber. Further, lower-quality lumber is often sold green; it is rarely kiln-dried.

StackingOnce sorted, the green lumber is stacked for drying in order to maintain the highest quality (Figure 9). Lumber is stacked in layers, with all the lumber in each layer being the same thickness. A layer is typi-cally 4 to 6 feet wide. Narrow layers result in faster drying, but also result in piles that can tip over more easily. The length of the layer is the length of the lumber, with the longer pieces being used on the outside edges.

5 '3/4"

1 1/2'

to 2'

stickers

Each layer of lumber is separated from the one above by wooden spacers called stickers. The stick-ers, made of any DRY species of wood, are placed perpendicular to the lumber’s length. The width of the layer is the length of the sticker. The stickers are spaced, starting at one end of the lumber, every 24 inches (although many operations use 12-, 16-, or 18-inch spacings in order to keep the lumber even flatter). The stickers keep the lumber flat and provide space for air flow in the drying process. The stick-ers in one layer must be perfectly vertically aligned (no greater than 1/2 inch variation) with the stickers in layers below and above. A pile or stack is several layers of stickered lumber.

It would be best if the lumber within one stack is all the same length. However, if a few shorter pieces are included (but never more than a 2-foot difference between the shortest and longest), then place the longer pieces on the outside edges of the layer and keep the shorter ones on the inside. The ends of the shorter pieces should always be supported with a sticker; therefore, an extra sticker may have to be used in some layers.

Once stacked, the lumber is placed in a good drying location (even if it will be sold in a few days) where the air can move through the package.

AS SOON AS THE LUMBER IS SAWN . . .

Drying RisksThere are three major risks for lumber that has been freshly sawn:

• The lumber is subject to attack from insects. • The lumber is likely to stain, including mold and mildew stains. • The lumber is likely to crack, if exposed to sun or dry air for a few hours before stacking.

To keep lumber valuable and to avoid wasting this precious natural resource, lumber must be handled correctly from the moment it leaves the saw. If handled improperly at the mill, especially the white woods like maple and pine, can develop stain within 24 hours during warm weather (although often the stain itself doesn’t show up until later). All species can develop value-reducing end splits within several days. Oak and beech are especially susceptible to surface cracks (or checks).

FIGURE 9

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Hardwood Lumber Grades and PricesThere are five basic grades of hardwood lumber (Figure 2)—FAS, Selects (sometimes sold as FAS 1-Face), No.1 Common, No.2 Common, and No.3 Common. Here is a brief summary of the grades:

FAS is a piece of lumber that is at least 83% clear on the worst side of the piece. (Clear means free from rot, pith, shake, wane, knots, stain, and other defects.) The clear area or areas are wide and long; the lumber itself must be at least 6” x 8’.

No.1 Common is at least 67% clear on the worst side of the lumber. The clear areas can be smaller

HARDWOOD SAWING TECHNIQUESThe initial sawing operation is THE KEY to obtaining the highest dollar return and the most useful lumber from every log processed. The operator of the saw, the “sawyer,” must recognize the potential product grade mix that will maximize the value of the log, and then manipulate the log to achieve this maximum value. This requires a “sixth sense” with x-ray vision to visualize what is inside the log before it is sawn.

In order to do an effective job, the sawyer must receive logs that have been properly felled and handled. Logs should not have large protuberances, pronounced crook, kink, or sweep, or jagged ends. Log ends should not be dried out. In short, the sawyer is no magician—the way that logs are harvested, bucked to length, and stored before sawing affects their potential value when sawn into lumber.

To optimize log and product value, the sawyer must also consider how the lumber will be edged and trimmed. If the edging and trimming are not done by the sawyer, then the edgerman, trimmerman and sawyer must develop good communication along with a high degree of skill and judgment. They must act together as a team. They also must operate their equipment safely and efficiently. As a minimum, these people must have a thorough understanding of lumber grades and current lumber values.

FIGURE 2

FAS$9.50

No.1C$6.50

No. 2AC$3.00

No. 3AC$2.25

No. 3BC$1.75

wane

knots

split

worm holesstain

than with FAS. Common lumber can be as short as 4’ and as narrow as 3”.

Selects and FAS 1-Face are No.1 Common pieces that have the better face equivalent to FAS.No.2 Common is 50% clear on the worst side and stain is a defect, but with No.2B Common, stain is not a defect and is ignored.

No.3A Common is 33% clear on the worst side. The lowest grade, No.3B Common, requires only 25% of the piece to be sound, not clear.

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SAWMILLING QUALITYSawing procedures will influence lumber quality. The following criteria are the technical basis used to develop the suggested sawing procedures discussed in the next section:

• The clearest, knot-free, strongest, most valuable lumber is on the outside of a log. Quality goes down as the lumber is sawn closer to the center (called the pith) of the log.

• Wide, long, clear pieces of lumber are the most valuable. The best hardwood lumber grade guarantees that the lumber is at least 83% clear. Attending a three-day hardwood lumber grad-ing class is well worth the time and expense. Contact the National Hardwood Lumber Association for the dates of a class in your area: (901) 377-1818. Hardwood lumber graders do not need to be certified or licensed.

• Softwood lumber grading is much more complex than hardwood lumber grading, and due to safety concerns, must be done by a certified, licensed grader. Most wood framed buildings are required by the building codes to be built with graded, certified lumber. Check with local building officials for specific requirements and rules in your area.

• Quartersawn lumber (with the rings going from face to face, rather than edge to edge) requires up to 30% longer drying time. Quartersawn lumber has a different grain pattern than flat-sawn, especially in oak, ash, sycamore, beech, and hackberry. This grain may be unwanted by some customers. When sawing quarter-sawn lumber, yields of lumber from the log are reduced, compared to more typical sawing pat-terns. Quartersawn lumber may also shrink up

Face 2

Face 4

Face 3

Face 1

Knot

SeamFIGURE 1to 1/16-inch more (per inch of thickness) than flatsawn lumber during drying, meaning that the green size may have to be increased, further reducing yield.

• Thick lumber requires substantially longer drying time and milder drying conditions. For example: 8/4 requires 2.5 times longer for drying than 4/4 lumber. Therefore, in most cases, saw lumber no thicker than required. Do not saw thick lumber that will be resawn into thinner pieces after dry-ing. If thicker pieces are required, consider saw-ing thinner pieces to glue together later. After sawing, keep them in order, so that after drying you can glue them back together in the same order that they came from the log. In this way, the grain of the small pieces matches very well; it will be difficult to see that the large, thick piece is actually made of several glued-up pieces of wood!

• Lumber that has the rings off center (when look-ing at the end grain of the lumber) will bend to the side more often than not. Therefore, always try to keep the rings centered so that the two edges of the lumber are mirror images.

• Lumber including the pith will warp badly at times and will almost always develop a large split.

• Lumber from crooked logs has high slope of grain (SOG). High SOG also results when the lumber is not sawn parallel to the bark. Lumber with such grain pattern will often warp badly during drying. Lumber with a high SOG has greatly reduced strength as well. Often, the strength is critical when sawing softwood con-struction lumber, so SOG is an important factor to consider when evaluating and sawing logs. Lumber with high SOG also machines poorly, with grain tear-out and raised grain common.

• Softwood lumber intended for construction purposes, with large knots near the edge is not as strong as if the knots were in the center face. Knots on the edges running toward the center of the piece, called spike knots, make the piece of lumber especially weak. Lumber with large knots is weaker than lumber with smaller knots.

• Lumber intended for remanufacturing, especially lumber that will be cut up into smaller pieces for furniture, cabinets, and so on, is most valuable if the knots are near an edge or end, maximizing the size (length and width) of the clear, knot-free areas in the lumber.

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2Initial DryingThe best results are obtained if the lumber is put into a kiln or into controlled drying as quickly as possible. The second best approach is using a shed (a pole shed without walls is ideal) where the lumber is pro-tected from direct rain and sun. Drying sheds require good air flow, so a barn or closed shed is usually too slow. On some species, adding fans to the shed will help develop the lightest, brightest color. By shed-drying before kiln-drying, the annual volume of lum-ber dried in the kiln can be quadrupled, compared to kiln-drying green-from-the-saw.

Air-DryingRemember: Slow drying, such as from slow airflow or high humidity, may result in stain. Fast drying, such as from excessive airflow or low humidities, can result in excessive cracking and splitting. The air-drying process needs to be controlled as closely as possible to avoid extreme conditions that may result in quality loss.

The pile is usually stacked at least 12 inches above the ground to avoid trapping moist air under the pack. The pile should be covered on the top to prevent direct exposure of the lumber to rain and sunshine. More complete instructions on options for quality air-drying are included in Air Drying of Lumber, U.S. Department of Agriculture Handbook No. 402. Although out of print, this handbook is available in most large libraries and can be obtained on inter-library loan from most smaller libraries.

Although air-drying is simple and easy, it is not unusual to have in excess of 10% loss in quality due to the variability and extremes of the weather. Can you afford this? If not, consider shed-drying. (If someone stole 10% of your lumber, wouldn’t you do something about it?) As mentioned, in shed-drying, lumber is placed in an open shed, thereby avoid-ing direct sunlight and rainfall. Drying rates can be regulated by using plastic mesh curtains--pull them closed during hot, dry weather; open them during cool or damp weather. Final moisture is typically over 20% MC.

With either air-drying or shed-drying, the lumber piles need to be placed on a flat foundation with at least 8 inches of clear area underneath. If the air under-neath the piles cannot flow out easily, high humidities will develop under the piles leading to poor drying and a risk of stain. If the foundation is crooked, then warped lumber is likely.

Kiln-DryingThe process referred to as “kiln-drying” involves putting the lumber in a chamber in which the tem-perature, humidity, and air velocity through the lum-ber are controlled. By controlling these three environ-mental variables, the drying rate and the quality of the lumber are controlled. Final moistures are as low as 6% MC.

The smaller producer of kiln-dried lumber has several major choices of equipment. As a broad generaliza-tion, solar-heated dry kilns are best for producing under 25,000 board feet (25 MBF) of lumber annually. Under 2 million board feet (2 MMBF), most operations will find that an electrically operated dehumidification (DH) kiln is best.

Plans for building a solar kiln are available on the Internet (www.woodweb.com). Solar kiln kits are available from Wood-Mizer. Often, a solar kiln will pay for itself after drying just three or four loads of lumber.

Dehumidifier kilns are more expensive than solar, but can provide top quality kiln-dried lumber year-round, regardless of whether the sun is shining or not. Economic aspects of a dehumidifier kiln are dis-cussed in Opportunities for Dehumidification Drying of Hardwood Lumber which is available from the Virginia Forest Products Association (P.O. Box 160, Sandston, VA 23150). The cost of operating a DH kiln can be as high as $75 per MBF. However, the value added by drying is often $300 per MBF. The return on investment with a dehumidifier can be over 20% after taxes.

Dryer operation is discussed in many texts. Three- to five-day short courses are conducted annually throughout the U.S. and Canada. Look for advertisements in trade magazines or contact state forest products specialists.

LUMBER DRYING

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HOW DRY IS DRY ENOUGH?Lumber should be dried to a final MC that is as close to the expected MC that the wood will achieve in use. This guideline is established so as to avoid warping and size change problems in the final product. The MC of wood in-use is related to the relative humidity (RH) that the wood is exposed to; temperature is irrelevant. Different species have the same in-use MC if exposed to the same RH. A special term is used to relate RH to MC in wood; the EMC (equilibrium moisture content) of air is numerically equal to the MC that wood will have when exposed to a given RH. The following tabulation (Table 4) summarizes this relationship.

RULE: The basic rule for drying lumber is that the final MC in the kiln should be within 2% MC of the expected EMC in-use to avoid moisture-related problems. Failure to observe this rule can easily result in manufacturing losses exceeding $1000 per MBF, as well as loss of future sales and customers, and may even result in a law-suit.

As a general rule of thumb, wood shrinks in width or thickness about 1% for every 4% MC change. (This is a general rule, with some variation from species to species. Teak shrinks much less, 1% for 8% MC; oak shrinks much more, 1% for 3% MC.) This means that if a 2-1/2-inch-wide piece of oak loses 3% MC, it will shrink 1% or 0.025 inches! This seems like a small amount of shrinkage, but when gluing, the maximum gap allowed between two pieces of wood is only 0.006 inches. Further, if this oak piece is actually a piece of flooring in a 30-foot wide floor and the entire floor is losing 3% MC, the total shrinkage is 4 inches, which probably is dis-tributed across the floor with objectionable cracks every foot or so.

Table 4 The relationship between humidity, EMC and wood use in North America.

RH MC EMC Condition

% % %

0 0 0 Oven-dry

30 6 6 Lower limit in most homes and offices Lower limit for hardwood furniture and cabinet lumber

36 7 7 Average for hardwood furniture and cabinet lumber

44 8 8 Lower limit for softwood remanufacturing lumber

50 9 9 Upper limit in most homes and offices Upper limit for softwood remanufacturing lumber

65 12 12 Average outside condition, winter and summer Average for softwood construction lumber

80 16 16 Outside condition for coastal areas

Achieving Proper Final Moisture ContentLumber needs to be properly stacked, with sticker openings being uniform in size. Narrow piles (6 feet or under) have more uniform drying than wider piles. In dry kilns, uniformity of temperature, relative humidity, and velocity is required. This uniformity is most critical when the lumber is above 40% MC and also when the lum-ber is under 10% MC. In the kiln, uniform airflow and frequent airflow reversal (two hours) improve uniformity. Equalization should be used for as long as required to achieve the desired uniformity of final MC—it may take longer than 24 hours with some loads. The lumber should be as uniform in thickness and initial MC as possible.

Moisture samples need to be accurate and properly prepared. With as many as 5000 pieces of lumber in a kiln, will just 8 or 10 samples give an adequate picture of the final MC? I suggest 30 samples be taken using a hand-held moisture meter when the kiln is being unloaded to ascertain the correct final MC. When such sam-pling is done, also look for areas in the kiln that are consistently wetter or drier than other areas. Make sure that your moisture measuring technique can detect pieces under 6.0% MC—over-dried lumber is a serious quality problem when machining or gluing.

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Log value is based on the amount and value of lum-ber that will be produced. Based on the results from sawing thousands of hardwood logs, the volume of lumber produced, total and by grade, and the value of the lumber produced from any size and grade log can be estimated. Several examples for red oak logs are given below (Table 1).

Logs that are crooked or short will produce much less high-value lumber than long, straight logs. Further, logs eight feet and shorter will seldom pro-duce much high-quality lumber. Therefore, when bucking a tree into logs, always try to maximize log length, but at the same time, minimize crookedness. These log length bucking decisions are critical for large diameter logs. On the other hand, logs under 16 inches in diameter (small end, inside bark) will seldom produce much high-quality lumber, so length decisions for these smaller logs are not very critical. Incidentally, it is typical that the length of logs is usu-ally about 2 inches over the last full foot; that is, an 8-foot log is really 8' 2", an 11-foot log is 11' 2", and so on.

Once the logs have been manufactured, they need to be handled correctly and sawn promptly. Appreciate that the way the logs are handled influences lumber

PART 1 Sawing the Best Lumber

Table 1 Lumber volume and value from various sized red oak logs

Log Log Log Lumber Diameter Length Grade Selects & Btr No.1C No.2C No.3C Value (inch) (feet) (Bd Ft) (Bd Ft) (Bd Ft) (Bd Ft) ($)

12 10 3 2 11 20 25 32 12 12 2 12 20 23 17 51 14 10 3 4 18 27 30 47 14 12 2 20 33 28 20 76 15 12 2 25 40 31 20 90 16 16 1 90 45 34 13 173 16 16 2 40 64 44 29 140 16 16 3 12 44 53 56 103 20 12 1 124 54 31 18 223 24 12 1 197 81 33 22 338

L U M B E R P R O D U C E D

quality. Logs stored for more than several weeks in warm weather may have already begun to stain, especially at the log ends and wherever the bark has scuffed off. Therefore, prompt sawing of logs in warm weather is essential.

Exposed log ends also are likely to begin drying immediately, resulting in development of stain, end cracks, splits, and checks. It is quite easy for the stain and cracks to penetrate over six inches in just a few months. Further, the dry ends are difficult to saw accurately. The saw wanders excessively in this dry wood, giving erratic lumber thicknesses. Therefore, all logs should be end-coated promptly with a vapor resistant coating (commercial wax coatings, such as Anchor Seal, are very popular) to prevent end checks and reduce the risk of end stain.

In addition to the damage that can be seen, such as end stain and end cracks, stored logs have certain undesirable chemical changes occurring within the wood. Lumber from logs stored several months dur-ing warm weather is at least 10 times more likely to develop cracks and checks in drying. Lumber from stored logs is perhaps 20 times more likely to develop objectionable drying stains, including sticker stain.

LOG QUALITYIt is difficult to produce high-quality lumber from logs that are knotty and crooked. Effective sawing decisions require knowledge of the logs’ quality. So, the first step before sawmilling begins is always to evaluate or grade the logs to estimate their quality. Logs are graded based on their faces. A log has four faces, each face repre-senting 1/4 of the circumference and being the full length of the log (Figure 1). The four faces do not overlap each other. A clear face is free of knots, knot scars on the bark, seams, splits, rot, insect damage, and so on. The clearer the face, the higher the value and the better the lumber that will be produced from the log. Detailed instructions for log grading are available from many state forestry offices, or request Forest Facts #74 (send $2 and a SASE) to the Forestry Department of the University of Wisconsin, 1630 Linden Drive, Madison, WI 53706.

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Freedom from Checks and SplitsAll lumber should be end-coated as soon as possible after it is sawn. Good stacking and good control of lumber lengths will help prevent the ends from drying too quickly. High relative humidity at MCs above 40% are critical. Moderate air flows and lower tem-peratures are also important. Above all, the drying rate must be controlled to within narrow limits—the precise rate depends on the species and thickness of the lumber.

Freedom from WarpExcept for cupping, and warp caused by bad stack-ing (such as non-uniform sticker thickness, poor sticker alignment, or non-flat foundations), all warp results because of wood factors and sawmilling pro-cedures. Cup is a result of rewetting partially-dried lumber or over-dried lumber.

Freedom from Casehardening (Drying Stresses)The procedures for proper stress relief (also called conditioning) require the rapid addition of moisture to the lumber surface when the lumber is warm. Often the heat in the steam used for stress relief will increase the kiln temperature above the required level, leading to poor relief. Use of water to cool the steam or cooling the lumber prior to steaming should be considered. Using 180 F air temperature (often called the dry-bulb temperature) is suggested. Note that stress relief will be erratic if the lumber’s MC is not uniform when stress relief begins. Water spray systems can be used in lieu of steam spray. Solar kilns do not require stress relief, as the nighttime high humidities provide freedom from casehardening.

Good ColorBy far, the most critical factor determining lumber’s color (or discoloration) is log freshness. Old logs have 20 times or more risk of developing stain–fun-gal stains, sticker stains, browning, pinking, graying, and so on. Freshly sawn lumber requires low humidi-ties, low temperatures and brisk velocities imme-diately after stacking and until the lumber is under 30% moisture content to control stain. Narrow loads and partially-filled dryers will help. Poor stacking and exposure to rain increase the risk of stain.

High StrengthLow humidities and low dryer temperatures will maximize the strength. Other strength-lowering factors, including bacterial and fungal effects and species effects, are beyond our control.

Good MachinabilityWood that is too wet will fuzz. Wood that is too dry (under 6% MC) will chip, split, and develop other machining defects. Make sure that you monitor the driest pieces of wood in the dryer as well as the wet ones–don’t underestimate the effect of over-drying on machining. Avoid temperatures over 160 F and avoid very low humidities in the drying schedule. (Conditioning or setting the resin at 180 F is accept-able, however.)

Good GluabilityGood gluing requires accurate final MCs. Check for pieces that are too wet (typically over 8.0% MC is too wet), and too dry (under 5.5% MC is too dry). Avoid temperatures over 160 F in the main drying schedule. (Conditioning or setting the resin at 180 F is acceptable, however.)

ADDITIONAL QUALITY CHARACTERISTICS OF THE DRYING PROCESS

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Oven-dryingIn the oven-dry test, a small piece of wood (called a moisture section) representing a large piece of lum-ber is first weighed. The weighing is typically to the closest 0.01 ounces, so a postal scale is not accu-rate enough. Then the moisture section is put in an oven heated to 215 F. (A kitchen-type microwave can also be used if the oven has a carousel tray, and is set to medium low for 20 to 40 minutes. Do not leave the oven unattended, however, as the section sometimes may begin to smoke.) After approximately 24 hours, the section is weighed again, dried for one more hour, and then weighed again. If these two final weights are the same, then all the moisture has been evaporated; the section weight is the oven-dry weight. The MC is calculated using this formula:

An alternate formula is:

Electric MetersThe oven-drying test is a destructive test and requires 24 hours to get the reading. The MC can be measured rapidly and non-destructively by using electrical methods. It was discovered years ago that the electrical resistance is fairly well-related to MC. With the meter, pins are driven into the lumber and the resistance between the pins is measured. A second relationship was discovered between the dielectric coefficient and the MC. Meters based on this principle use a flat plate that is intimate contact with the wood.

Both types of meters are fairly accurate estimators of the MC. Each also has certain advantages and certain disadvantages. For example, the resistant meter can measure a gradient, depending on how far the pins are driven into the lumber. The resis-tance meter also is not strongly affected by different species. The dielectric meter is not affected by the temperature of the wood. The dielectric meter can also quickly scan the lumber’s surface looking for wet spots or wet pieces. Anyone kiln drying wood needs to have both types of meters—the best meter is always the same one that your customer is using!

The disadvantage of both meters is that they can-not be accurately used above 30% MC. That means that they cannot be used to run a kiln drying lumber “green from the saw.” The oven-drying procedure is the only reliable MC measuring system for kiln oper-ation in most cases.

% MC = ------------------------------------------ x 100 (wet weight — oven-dry weight)

(oven-dry weight)

% MC = [ ----------------------- — 1 ] x 100

(wet weight)

(oven-dry weight)

SUMMARY • Lumber drying is an easy, profitable manufacturing technique.

• Air-dried lumber must be stacked correctly, protected from the

elements, dried at the correct rate, and dried to the correct MC.

• If proper procedures are used, the lumber will be flat, bright, and free from cracks, checks, and splits.

MEASURING MCMoisture content is a key parameter in wood processing. The MC values are measured daily when operating a dry kiln. Depending on the MC, the temperature may be raised or the relative humidity lowered. In the dried product, any change in MC is accompanied by warping, shrinkage (moisture loss), and swelling (moisture gain). As a result, it is important to measure the MC accurately.

Moisture is measured in two ways: oven-drying and electrically.

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Wood is a valuable material. Although wood is plentiful in the U.S., with annual growth of hardwoods exceeding harvest by 25% for the past 75 years, we need to assure that we will not waste this valuable natural resource as we convert it into lum-ber, and as we convert the lumber into furniture, cabinets, buildings, and other useful products.

A nice size tree has just been felled in the woods. Your plans are to saw as much of the tree as possible into high quality lumber. You want to do this with a minimal amount of waste and, at the same time, you want to maximize the value and useful-ness of the lumber you produce. How do you proceed?

This text was written to provide both the hobbyist and the professional with basic, practical information on how to saw and dry lumber efficiently with minimal loss and downfall. The best operating procedures begin in the woods just after the tree is felled. In Part 1 of this booklet, practical, efficient sawmilling procedures that are dis-cussed and illustrated. Suggested drying procedures are then presented. As a con-clusion to this text, the final section lists sources of additional information on sawing and drying.

All the information presented is based on decades of experience. Therefore, unless there is a good reason not to follow the suggestions presented here, these guidelines will be the most profitable and will waste as little of our resource as possible.

We hope that you find all the information you need to convert our valuable, renewable resource into useful and durable wood products that will last for centuries.

HOW DRY IS DRY ENOUGH?

Achieving Proper Final Moisture Content. . . . . . . . . . . . . . . . . . . 20

ADDITIONAL QUALITY CHARACTERISTICS OF THE DRYING PROCESS

Freedom from Checks and Splits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Freedom from Warp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Freedom from Casehardening (Drying Stresses). . . . . . . . . . . . . . 21

Good Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

High Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Good Machinability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Good Gluability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

MEASURING MC

Oven-drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Electric Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

PART 3 Additional ResourcesSAWING AND GRADING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

DRYING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Gene Wengert

is Professor and

Extension Specialist

Emeritus, Department

of Forest Ecology and

Management, University

of Wisconsin-Madison,

and President of The

Wood Doctor’s Rx, LLC.

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PART 1 Sawing the Best LumberLOG QUALITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

SAWMILLING QUALITY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

HARDWOOD SAWING TECHNIQUES

Hardwood Lumber Grades and Prices. . . . . . . . . . . . . . . . . . . . . . 7-8

Hardwood Sawing Patterns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Opening Face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Specific Sawing Suggestions

General Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Log Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Opening Face Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Sweepy Logs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Quartersawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

SOFTWOOD SAWING TECHNIQUESawing Softwood Logs Into Construction Lumber . . . . . . . . . . 14

Sawing Softwood Logs into Boards and Lumber for

Remanufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

PART 2 Drying the Best LumberWHY DRY LUMBER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

MEASURING MOISTURE CONTENT. . . . . . . . . . . . . . . . . . . . . . . 17

WATER IN THE WOOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

AS SOON AS THE LUMBER IS SAWN...

Drying Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Stacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

LUMBER DRYING

Initial Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Air-Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Kiln-Drying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

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Drying Source Book: 40 Years of Drying ExperienceEdited by E. M. Wengert and R. Toennisson. Available from Forest Products Society, 2801 Marshall Ct., Madison, WI 53705.

Drying Hardwood Lumber, By J.Denig, G. Wengert and W. Simpson. Available (free) from Publications Department, Wood Eduction & Resource Center, 301 Hardwood Lane, Princeton, WV 24740.

Drying Oak Lumber, By E.M. Wengert. Available from University of Wisconsin--Forestry Dept., 1630 Linden Dr., Madison, WI 53706.

Opportunities for Dehumidification Drying of Hardwood LumberBy E.M. Wengert & OthersAvailable from Virginia Forest Products Association, P.O. Box 160, Sandston, VA 23150.

Applied Drying Technology, 1988 to 1993; and Applied Drying Technology, 1978-1988, By M. R. Milota and E.M. Wengert. Available from Forest Products Society, 2801 Marshall Ct., Madison, WI 53705.

Dry Kiln Operator's ManualEdited by W. T. Simpson and Others. Available from Forest Products Society, 2801 Marshall Ct., Madison, WI 53705.

Dry Kiln Schedules for Commercial WoodsBy R.S. Boone and Others. Available from Forest Products Society, 2801 Marshall Ct., Madison, WI 53705.

Design and Operation of a Solar-Heated Dry KilnBy Brian Bond. Publication 420-030, Dept. of Wood Science and Forest Products, Virginia Tech, Blackburg, VA 24061.

Web Site: www.woodweb.com (Sawing and Drying Message Board)

Sawing and Grading

Rules for the Measurement & Inspection of Hardwood and Cypress Written by and available from NHLA, P.O. Box 34518, Memphis, TN 38184.

NHLA Inspection School ManualWritten by and available from NHLA, P.O. Box 34518, Memphis, TN 38184.

What is hardwood? How is it graded? (14-minute video)Produced by and available from NHLA, P.O. Box 34518, Memphis, TN 38184.

Basics of hardwood lumber grades (10-minute video)Produced by and available from NHLA, P.O. Box 34518, Memphis, TN 38184.

Small Sawmill Handbook: Doing It Right and Making MoneyWritten by Joe DenigAvailable from the Forest products Society,2801 Marshall Ct. Madison, WI 53705.

Sawing, Edging and Trimming Hardwood Lumber By Joe Denig and Gene Wengert. Available from the Forest products Society, 2801 Marshall Ct. Madison, WI 53705.

Lumber yard insects (22-minute video)Produced by and available from NC State University, Campus Box 7603, Raleigh, NC 27695-7603.

Wood Using IndustriesDirectories are usually issued by most state every few years. Contact the state Department of Natural Resources, Forest Products Utilization Specialist.

Web Site: www.woodweb.com (Sawing and Drying Discussion /Message Board).

Sawmill & Woodlot Management magazine (targeting small producers). Subscription information available at www.sawmillmag.com

PART 3 Additional ResourcesContact the sources listed to determine availability and cost. Most of the items listed will require prepayment.

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8180 West 10th StreetIndianapolis, IN 46214

800.553.0182 woodmizer.com

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