MENG 351 Guitar ProjectNeck Operations

Materials Wood: ¾” x 2.25” cherry. ¼” wide spruce filler stick. Birch veneer. Hardware: 1/4" x 3/8” steel bar for reinforcement (“truss rod”). Two ¼-20 threaded inserts Medium-viscosity superglue (cyanoacrylate) and accelerator

Prepare Neck (Loma 7)

Miter Saw Review instructions behind saw; see instructor if machine is new to you. Cut neck stock to 24.0” length.

Table Saw Review the Table Saw instructions posted on the fence. Check the calibration of the Wixey digital fence read-out (rip a test piece and measure with calipers). Inspect the 2 edges for straightness. Do a minimum clean-up on any rough or wavy edges. (Omit

featherboard if edge is very rough.)

Rip stock to 2.25” wide, +/- 1/64”. Avoid feeding too slow—will burn the wood. Inspect the wood for bow along its length:

o Place the wide (2.25”) face against the fence. Solid wood is usually slightly bowed; Check that the bow is less than 1/32”, preferably ~1/64”:

o In pencil, mark the Top and Back as shown.

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On the Back Side, mark lines across the 2 1/4” width, at 3 1/4” and 6 1/8” from one end:

Cut Headstock Scarf Joint:o Setup the Table Saw Cross-Cut Guide in the slot to the right of the blade (left pic below). o Raise the blade to 2.75”. o Install the Adapter Clamp pins into the Cross-Cut Guide holes (left pic). o Rotate the Cross-Cut Guide counterclockwise to 15 degrees (pull pin), and lock. o Install the neck to the left of the Adapter Clamp with the neck’s back side towards the blade.

Align the 6 1/8” line with the front face of the clamp (right pic). Check that the blade touches the 3 1/4” line. Clamp securely.

o Stand to the right of the blade. Pull the Adapter Clamp tight to the Cross-Cut Guide (left pic). o Carefully cut the scarf joint in one ~slow, smooth motion. Don’t feed too quickly, as excess

force will result in a curved cut. (right pic)

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Truss Rod (Steel Reinforcement) Prepare Truss Rod

o Horizontal Bandsaw: Cut 1/4" x 3/8” steel bar to 16.0” long.o Disc Sander: Deburr ends so sides and corners of rod are smooth (Picture at left).o Clean/degrease thoroughly with Simple Green and Scotchbrite pad (Picture at right), followed

by wiping with isopropyl alcohol.

Table Saw: Cut Sloto Set blade height to 0.50” (left pic). Set the fence to 1.00” (exact, right pic).

o Place the angled end towards the blade (push stick fits square end). Cut the slot (full length).

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o Set the fence to ~1.06” and repeat. o Set fence to 1.14” (exact) and repeat. o Check the fit of the steel bar in the slot. A slip or slightly snug fit is ideal. If too tight, set the

fence 0.01” wider and rip again. Obtain a ¼” wide Spruce filler stick. Check that it fits snugly in the slot.

Mark the back of the neck at 1.0” inboard of the old 6 1/8” line, to define placement of the rod (right pic).

o Test fit the rod in the slot, with one end aligned to the new 1.0” mark. o Verify that the whole length will sit 1/8” deep in the slot. Remove the rod.

Square End (not flush to end) Scarf Joint End (at 1” line)

Apply beads of superglue (CA20) to the inside of the slot, to both side walls. o Fit the rod in the slot, aligned as above. Press or hammer in securely along its length (left pic). o Apply superglue to the inside of this “new” slot. Align the filler stick with the square end.

(right pic). Press/hammer the filler stick into the slot. Let dry 1 minute.

Belt Sander: Sand the Filler Stick flush with the back of the neck. Orient neck ends vertically so sanded surfaces remain flat.

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Finish Scarf Jointo Flip the endpiece over and fit to neck as shown below. Align the top faces with a ruler.

Check for good fit all around (see instructor if not). Pencil a short line across the aligned joint for use later.

o Apply superglue fairly generously to 1 face, align the pencil marks, and clamp securely for 3 minutes using 4 clamps (don’t use accelerator beforehand – repositioning may be needed). Quickly inspect the joint and move the clamps as needed to close any gaps.

o Carefully sand the top and side faces flat, until the joint is smooth.

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Headstock Veneer: o Obtain a piece of 3M sticky-back (PSA) maple or birch veneer (left pic). o Align edge of veneer just to the left of the headstock’s beveled edge (right pic). Press veneer

to surface.

o Press/rub veneer securely onto headstock using wood or plastic (left pic). o Trim extra veneer with a razor-knife (right pic).

o Using a ~150 grit sanding block, sand edges of veneer flush to headstock (left pic). o Sand the beveled edge so that the veneer isn’t higher than the neck’s fretboard surface (right

pic).

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Cut Nut Sloto Install the Cross-Cut Guide and set at the standard 90 angle. o Raise Table Saw Blade to 0.187” (3/16”, 6/32”, picture at left).

o Make a pencil mark aligned with the transition from headstock to neck.

o Position the Neck so the pencil mark is aligned with the table saw blade (left pic). Cross-cut the nut slot right through this angled edge:

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Headstock Layouto In pencil, layout the 6-hole tuning-machine pattern, 3/8” inboard from sides and 1.5”, 3.0”, and

4.5” from nut slot (left drawing)o On the back of the headstock, layout the end-of-headstock design, approx 6.0” from slot (right

drawing). A suggested design is shown, or, design your own.

Layout end pattern on back of headstock

Pocket Neck Joint hole layout and End-of-Neck lineo On the top surface, layout 2 hole pattern and the end-of-neck line, measured from the nearer

edge of the nut slot. (Hole diameter will depend on type of neck joint, below.)

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Drill Press Review instructions for drill press posted on the belt cover; see instructor if needed. Set speed to 2000-3000 rpm. Headstock:

o Hold Headstock in vise, using Guitar Headstock Backing Block to support back surface. o Install ¼” diameter brad-point drill bit (left pic).o Carefully line up tip of drill bit with center mark. o Drill 6 holes perpendicular to the headstock surface. (No pilot hole is needed for wood.)

Pocket Neck Joint: There are two options for the holes (locations marked on the prior page): Visible screws (1 minute) and Blind screws (15 minutes)

o Visible screw heads (limited to a maximum of 15 frets): Drill the 2 holes at 3/16” dia. o Blind screws installed from inside:

Drill 2 center-holes 1/16” dia, perpendicular to the neck surface. Turn the neck over for drilling on the backside. Install a 11/32” brad point drill bit. Set the Drill Press Depth Stop so the drill will not break through the top surface –

suggested hole depth is 9/16” (left pic).

Carefully align to the 1/16” holes and drill these blind holes (left pic). Install Threaded Inserts into holes using a 6mm Allen key. Install and gently sink to

bottom (right pic).

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Tablesaw/Chopsaw/Bandsaw End of Neck Cutoff at 17.06” line

o First check that the steel rod is set inside far enough to clear the blade (left pic).o If cutting with the tablesaw, transfer the 17.06” pencil line to the side as shown (right pic).

o Cut the end-of-neck at the 17.06” mark (left pic).o Optional: Bevel the top edge about 1/8” with the sander or a file (right pic).

View from back of Tablesaw

End of Headstock Bandsaw: Turn the neck upside down so the headstock sits flat and stable on the bandsaw table (layout lines were made on this back surface—page 7). Cut the pattern.

o Sand as needed. Do final sanding with a 120 grit hand sanding block to remove any burn marks.

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Fret Slots (Loma 5)

Frets are small T-shaped metal ribs installed on the neck, which allow changing the length (and thus frequency) of the vibrating string. Frets have this cross-section:

Fret locations are calculated from this formula (n is the fret number, 12 breaks the octave into 12 notes, and 2 doubles the frequency over 1 octave):

Below are the first 19 fret locations for a 25.0” Open String Length (distance from inside edge of Nut to the Saddle. Also has 0.015” nut compensation). The number of frets is up to you; logical values are 7 (for chords), 12 (1 octave), 14 (at the body joint), 15 (1 beyond body joint), or 19 (whole neck, but the extra 4 are mostly cosmetic). 14-15 are suggested.

Fret Distance fromNumber Nut Edge0 (Nut) 0.000

1 1.3882 2.7133 3.9634 5.1425 6.2566 7.3077 8.3008 9.2369 10.12010 10.95411 11.74212 12.48513 13.18714 13.84915 14.47416 15.06417 15.62118 16.14619 16.642

Tape the Fret Guide to the Neck, aligning the nut slot with the aluminum bar.

Use the mini-table saw to cut 7, 12, 14, 15, or 19 fret slots. If you aren’t sure, use 15 frets. o Pass the neck only forward through the blade (lift it up instead of pulling it back through

blade).

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Taper Neck (Loma 7) Initially, the nut width is tapered to ~1.78”; it will narrow to 1.75” with final sanding. On the back-side, pencil two lines across the neck:

o 1 line at 3/8” from the nut slot. o 1 line at 13.0” from the nut slot.

Tablesaw o Raise the blade to its full height (3.0”). o Install the Vertical Featherboard Attachment on the fence adjacent to the blade, and set the

magnetic clamps (left pic). o Set the featherboard lightly on the neck and tighten the featherboard clamp (right pic).

o Obtain the 5/16” Taper Spacers and securely tape them to both sides of the Headstock (left pic). Check that the tape is secure by sliding against the fence (right pic).

o Set the fence at 2.32” - 2.34”. Adjust the fence so the blade just starts to touch the neck near the 13” line (+/- ½”). (left pic)

o Rip the taper until the blade just reaches the 3/8” line (right pic).

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o Disconnect the Wixey digital read-out head from the fence (magnetic attachment, left pic).o Lower the blade. Slide the fence to the left of the blade. Raise the blade to full height again. o Setup the Vertical Featherboard Attachment , next to the blade (right pic).

o Adjust fence to just over 2 5/16” (equivalent of 2.32” – 2.34”, left pic). As before, adjust the fence so the blade just starts to engage the wood near the 13” line.

o Rip the taper to the 3/8” line as before.

o Measure the nut width. It should be between 1.74” and 1.78”. Adjust the fence and rip either/both sides again if needed.

Headstock Transition o Be careful sanding the transition from neck to the headstock – it is easy to gouge. Don’t

further narrow the width at the nut slot. o Pencil a diagonal line ~¾” up the headstock as shown (left pic). o Use the Spindle Sander to sand to the line, or form a radius (right pic).

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Radius Neck (Loma 5 - 6)

Pencil mark a line on all sides of the neck, 3 3/8” from the blunt square end (this line corresponds to the joint at the body).

On the back of the neck, layout the first set of boundary lines for rasping. o Here is the basic cross section of the first cuts:

o Draw these boundary lines for the Headstock (left) and Body Joint transitions:

Clamp the neck upside-down in a vice flush with the 3 3/8” line, using double-wrapped paper to protect the wood. The vise jaws will simulate the body side, preventing wood removal behind the 3 3/8” line (left pic).

We will use a 2 tools to carve the neck: A rasp and a coarse file, both half-round (right pic)

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Use a large rasp (a very coarse file for wood) to make heavy chamfers on both sides of the neck, cutting to the layout lines.

o Hold the rasp at both ends for control. o Use long sweeping strokes down the neck to avoid local gouges (left pic). o When rasping the far end of the neck, support the headstock against your torso (right pic).

o Use the round side of the rasp to taper the chamfer within the lines where it meets the headstock and body.

Continue with the rasp, chamfering the edges from the last cuts to create a finer-facet face, then rounding over all edges to create a smooth surface. Again, use long sweeping strokes up and down the neck for uniformity.

o Use the rounded side of the rasp to access the neck-headstock inside radius.

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o Aim to remove material for an elliptical cross-section.

Once the rasp has made a uniform surface, switch to a large coarse file and remove rasp all lines. The wood grain at the headstock and body joint transitions are prone to fraying—minimize this by stroking the half-round file towards the middle of the neck—not towards the ends.

Place coarse (80-100 grit) sandpaper under the file to remove the file lines and blend transitions.

Switch to a 1”x~12” length of 100-150 grit sanding strip, sanding shoe-shine style. o Keep moving up and down the neck to avoid gouges. o Keep the included angle more than 0° (splayed) to avoid narrowing the string-side. o Inspect the surface closely: you will probably find rasp lines that have not been fully

removed. Remove these with the coarse file (sandpaper would take forever).

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Measure the width of the neck at the nut slot: the goal is 1.75”. Use a sanding block to narrow the sides of the neck as needed. Round over any new edges created by this step.

Finish-sand the back of the neck with 180-240 grit sandpaper, this time sanding along the grain. Use a sanding block, or layer the paper to insulate your fingers.

Check the fit of the neck in the pocket joint. If too tight:o First thoroughly file the inside of the pocket joint to remove glue and other protrusions.o Then carefully belt-sand the sides of the neck until it is a slightly snug or slip fit.

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Obtain a 24” straight edge to check that the top neck surface is flat or bowed no more than 1/64” (concave up, like on page 1):

If the bow is excessive or convex, sand the surface flat using a 80-150 grit sanding block (pic below). Avoid sanding the headstock veneer.

Once the surface is flat, lightly sand the fret surface with a 180-240 grit block.

Lightly chamfer or radius all sharp edges with 120-180 grit sandpaper (folded over works well) and/or a file.

Carefully inspect and continue sanding the surfaces until you are satisfied. Flaws will be more visible after a finish is applied, and it is very difficult to correct them then. A bright light greatly helps inspection.

Clean-up the rasp and files with a file-brush before putting away.

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Neck Finishing (Optional—at least 1 coat is recommended, Loma 6)

Be certain you have sanded the surfaces to your satisfaction before applying finish. A good finish is “built” a thin layer at a time.

o Apply enough to fully wet the surface, but not so much that it appears to have thickness. o Inspect along the way to wipe up any runs – especially look at the edges and surfaces adjacent

to the surface just covered. o Don’t apply it thick– this causes runs, sags, uneven spots, and then more work to smooth out.o A bright light is essential to observe finish quality.

Using gloves and a small (~4”x4”) clean/lint-free paper towel/rag, apply dewaxed shellac (Zinsser Bulls Eye SealCoat) to the entire neck.

o Shellac dries extremely quickly, so avoid going over the same area twice. Apply to a small area (e.g. one face of the headstock), move on, and quickly wipe up runs.

o Be careful on the fretboard to not get shellac in the fret slots. Use a razor to clean these out if needed (right pic).

Let the shellac dry 1 hour. Run your hand over the surface: you’ll notice considerable roughness.

o Using 220-320 grit sand paper, lightly scuff-sand all surfaces a few times. Apply no more pressure than the weight of your hand (pic below).

o The goal is only to take off the high spots—any heavier sanding will cut through to wood. o Check that the surfaces are smooth.

Optional but recommended: Repeat with a 2nd coat of shellac, let it dry 1 hour, and lightly scuff-sand with 320 grit paper.

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Using a clean paper towel or rag, apply a thin coat of water-based lacquer (Target Coatings EM6000). Let dry 30 minutes. If this is your last coat, you can leave as-is or scuff sand with 600-800 grit paper or fine steel wool (000 – 0000).

Optional but recommended: Scuff-sand prior coat with 320 paper. Apply a 2nd coat of EM6000 and let dry 30 minutes. The surface should now be smooth and satin. If there is roughness, lightly scuff sand with 600-800 grit paper or 000 – 0000 steel wool. Repeat if desired.

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Make and Install Frets (Loma 5-7)

Make and Dress Fretso Carefully cut 7-19 frets using either the Beverly Shear or a Hacksaw/Vise. The Beverly Shear

can cut 3-4 fret sticks at once for mass production. Cut the first 6-8 frets to 2” long (left pic) Cut the remaining frets to 2 3/8” long (right pic)

o Belt Sander – Wear Hearing Protection (or manually with ~100 grit sandpaper). Many of the fret ends will be mangled from the shear (left pic). Line up the 2.0” frets and sand one end square: hold frets down with your fingers, then push

them in with a block – middle pics). Repeat for the 2 3/8” frets. The sanded end should be uniform (right pic).

o Place frets in the Taper Sanding Fixture with the squared fret ends pointed inward (left pic) o Sand the unsquared ends just to the edge of the Fixture’s front side (right pic).

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o Chamfer and round-over the sharp ends: Hold the fret at a shallow angle on 150-320 grit sandpaper (left pic). Coarse paper is faster;

fine paper gives a nicer surface. Pull the fret across the paper, increasing the angle as you pull to round over the end (middle

and right pics).

Hold a different part of the fret-end against the paper and repeat until the end is smooth all around. This will take a while.

Gently check that the ends have no sharp edges.

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Install each Fret in its slot. o Starting with the last fret at the body end, place a fret in its slot. It should sit ~1/32” inboard

of the neck edge on each side.

o Set the neck in the Fret Press (left pic). Align the aluminum nose centered over the fret (pics).

o Press until the fret is fully seated. But don’t over-do it; we’ll need some adjustment later. o Near the headstock, support the back of the neck with the concave block keep the neck level.

Check for uniform fret heights by setting a straight edge over the frets. o Start with a rigid 12” scale to find the highest frets. Attempt to rock the scale left-right; if it

rocks, find the high fret and press it a bit further into the wood. But don’t overdo it, as that would create a low fret. Check for the next highest fret and repeat (left pic).

o Switch to a short Machinist or Combination Square to check every 3 frets (right pic).

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Laser-cut Headstock Logo and Fret Markers (optional, Loma 311)

Computer for the Laser Cutter (L311_1) Turn on the computer and login as freshman, password is Engr@usd (Don’t use your own login.) Startup Autocad 2004 (NOT Autocad LT 2010) In Autocad 2004, select File-Open, migrate to the network drive Student_Files_Courses, then migrate

and open courses\MENG 351\MENG.351.Guitar.dwg

Laser Cutter Turn on both main power switches to the laser cutter and let it run through its startup routine.

Open the windows for ventilation. Find the 3-ring binder on the wall behind the laser cutter: “Instructions for Operation and Set-up of the

Laser Cutter”. On page 2, perform instructions #1 and #3. If the vacuum/honeycomb fixture is installed, carefully remove it.

Headstock Logo Place the Headstock Logo Fixture in the laser cutter, aligned against the ruler edges. (left pic) Place your neck on the fixture, aligning your headstock end with the V-mark and the other end against

the ruler. (right pic)

Use the Arrow Keys ( ←↑→↓) to move the laser depth probe over the headstock. Then press the Auto Focus button. Do not touch the Up/Down Arrow buttons after this.

In Autocad 2004, go View Named Views… double-click Headstock USD Logo OK(The view will change to the logo on the right—black lines are for alignment and will not etch)

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Press Control-P (plot) and make these settings: Printer/plotter Name: Mercury click Properties

In the new Plotter Configuration Editor window, click the Custom Properties button. o In the Mercury Properties window, select the Pen tab, and make these settings:

Color Speed PowerBlack (invisible lines) 100% 1%

Red (etch lines) 30% 100%o Click OK to exit Mercury Properties.

o Click OK to exit Plotter Config, then select Save changes to following file:, then click OK.

Click the Plot Settings tab, and verify/make these settings: Y = 16.0

o Click the Full Preview button: the Logo should be in the upper left corner. o Press the Escape (Esc) key ONCE to close the Preview. o Click OK: the plot file is sent to the laser cutter. o Files: The Laser Cutter stores each sent plot in sequence as File 1, File 2, etc (files are usually

erased on shutdown). The Next File button scrolls through them. Select the last file sent. o Perform a dry run:

o Open the plastic cover: this tells the laser cutter to substitute a red light for the laser.o Press the Start/Stop button. o The Laser Cutter will run the plot lines without cutting (it only cuts with the cover closed). o Observe that the logo is where desired (the circle and centerline are for positioning and will

not show). Adjust the wood if needed.o Stop the dry run by pressing Start/Stop.

o Cutting: o Close the cover.o Press Start/Stop. o The Laser Cutter will execute the plot. While cutting, don’t bump the Laser Cutter or press

the Up/Down buttons.

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o Start the large fan above the Laser Cutter to move fumes out the open windows. Stay with the machine to make sure a fire does not occur.

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Fretboard Markers The instructions below assume the Headstock Logo steps above have just been completed. Remove the Headstock Logo Fixture and replace with the Fretboard Marker Fixture. Align it with the

Lasercutter’s ruler edges as before. (left pic) Place your neck on the fixture, aligning the center of the nut slot with the arrows. (right pic)

Move the depth probe to the middle of the fretboard. Press the Auto Focus button.

In Autocad 2004, go View Named Views… double-click Fretboard markers OK Press Control-P (plot) and set Plot Settings Plot Offset X = 0.0, Y = 6.0 Repeat the steps on the bottom of the last page.

Fret Side Markers Keep the Fretboard Marker Fixture in place. Place your neck sideways against the fixture, aligning your nut slot with the aluminum plate (left pic). Move the depth probe to the mid-section of the neck (bottom right pic). Press the Auto Focus button.

In Autocad 2004, go View menu Named Views… double-click Fret side markers OK Press Control-P (plot) and keep the settings Plot Settings Plot Offset X =0.0 , Y=6.0 Repeat the steps on the bottom of the last page.

Cleanup Read the cleanup instructions on page 2 of the 3-ring binder: “Instructions for Operation and Set-up

of the Laser Cutter”. Replace the binder to its wall storage. Turn off everything except the computer.

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Tuner Installation (Loma 5-7)

Do all (optional) laser cutting before installing tuners. Insert the 3 left and 3 right Tuning Machines in their holes with white knob oriented further up the

neck.

Hand Drill o Install 1/16” drill bit, choked up into the chuck so only about ½” sticks out.

o Align a tuning machine to headstock edge. Pilot drill just the upper 1/16” hole approx ¼” deep. (Don’t do both holes yet).

o Align and drill 5 more upper holes for the remaining tuning machines.o Install screw for each drilled hole – tighten very gently. o Pilot drill all 6 lower holes, approx ¼” deep. o Install remaining screws.

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