Working with Common Plastics in the Woodshop

Plastics have a Place in “High End” Work

Shelves for Built-Ins

Art Glass for Doors

Glazing for Art Frames

Display Cases

Plastics Have Practical Uses in the Production

ShopSafety Shields and Guards

Guides and Slides

Push Sticks and Hold Downs

Shims and Spacers

Working Plastics with ToolsYou Already Own

Sharp, clean bits and blades will provide very good results with most common tools.

Table saw, Router, Bandsaw , Sander and even Hand saws are effective tools.

Friction causes melting , resulting in poor edge quality and “weld back”

Vibration and unsupported cuts can cause excessive tool marks and

chipping

Heat and Vibration are the Major Obstacles to Good

Results

Many Plastics Can Be Easily Worked with Hand

Tools

Drilling Requires Regrinding the Cutting Edge to Prevent “Self-feeding”

Flatten the back angle of the cutting edge

Achieve a scraping cut , rather than a digging one.

Common Plastics:

Acrylic- Good optical properties, but brittle and more prone to breakageGlazing applications, signage, protective covers, tool sub-bases

Common Plastics:

Acrylic- Good optical properties, but brittle and more prone to breakageGlazing applications, signage, protective covers, tool sub-bases

Polycarbonate- Lesser optical properties, highly impact resistantShields and guards, hold downs, tool sub-bases

Common Plastics:

Acrylic- Good optical properties, but brittle and more prone to breakageGlazing applications, signage, protective covers, tool sub-bases

Polycarbonate- Lesser optical properties, highly impact resistantShields and guards, hold downs, tool sub-bases

Nylon, Polyethylenes- Opaque, flexible, good wear characteristicsSlides, runners, wear strips, push sticks, backers , tool sub-bases

Common Plastics:

Acrylic- Good optical properties, but brittle and more prone to breakageGlazing applications, signage, protective covers, tool sub-bases

Polycarbonate- Lesser optical properties, highly impact resistantShields and guards, hold downs, tool sub-bases

Nylon, Polyethylenes- Opaque, flexible, good wear characteristicsSlides, runners, wear strips, push sticks, backers , tool sub-bases

PVC- Opaque, good adhesive properties, available in sizes and fittingsDC pipes and connectors, structural components

Common Plastics:

Acrylic- Good optical properties, but brittle and more prone to breakageGlazing applications, signage, protective covers, tool sub-bases

Polycarbonate- Lesser optical properties, highly impact resistantShields and guards, hold downs, tool sub-bases

Nylon, Polyethylenes- Opaque, flexible, good wear characteristicsSlides, runners, wear strips, push sticks, backers , tool sub-bases

PVC- Opaque, good adhesive properties, available in sizes and fittingsDC pipes and connectors, structural components

Styrene/ABS- Opaque, good adhesive properties, very thin sheetsSpacers, shim stock, templates

Cutting/Milling

Blades should be clean and sharp.

60-80 TPI seems to be optimal

ATB or “Triple Chip” grind scores edges before cuttingthrough

Zero-clearance inserts tosupport material

Cutting/Milling

Fine tooth band saw bladeswill successfully cut plastics

Edge quality will be poor

Sanding or routing is an effective method for cleaning up the edges

Cutting/Milling

Router bits are highly effective atcutting plastics

CNC machines can cut complexshapes in sheet plastics

Feed and RPM settings greatly effect edge quality. Pay attention to chip load.

Lower RPM with higher feed reduces friction heat and “melt-back”

Cutting/Milling

Milling with hand routers is most effective when using templates

Band saw oversize, then trim to template

Spiral bits are highly effective, leaving few tool marks

Lower RPM with higher feed reduces friction heat and “melt-back”

Hand Tools

Straight cuts in thinner plastics such as Acrylic or Styrene can be made by scoring a line and snapping the material very much like cutting glass.

Hand Tools

Thin Styrene/ABS can be cut with a utility knife to complex shapes.

Thicker parts can be scored and snapped as described previously.

Hand saws can cut most plastics effectively.

Dedicated Plastic Tooling

Saw Blades

Most manufactures make dedicated saw blades for plastics.

Look for 60-80 tooth Alternating top bevel or triple chip ground blades.

Dedicated Plastic Tooling

Router Bits

Most manufactures make dedicated router bits for plastics.

“O-flute” bits have a concave inner face that curls the plastic chip reducing stress and chipping during the cut.

Forming Plastics

“Soft” plastics like polycarbonate and styrene can be “cold formed” if thin enough.

A sheet metal brake can be used or the parts can be clamped in a vice and bent.

They will likely need to be over bent to account for spring back.

Forming PlasticsAcrylic or thicker polycarbonates can be bent with heat.

Apply pressure in the bend direction and gently heat the bend area with a torch until the part softens enough to bend.

Overheating will result in bubbles appearing in the heated area.

Forming Plastics

Many types of electric strip benders are available for bending plastics up to ¼ inch thick.

These heat the material slowly and safely to insure proper softening without over heating.

Edge Polishing

Clear plastics parts may require polished edges.

Sand edges in successive grits to about 400

Use a buffing wheel with compound to polish the edges clear.

Flame Polishing

A torch can produce a quick polished edge.

Sand to 220 grit

Pass flame quickly over the edge to very lightly melt the sanded surface

Parts can be stacked

Hydrogen/oxygen torch is most effective.

Adhesives

Acrylics and polycarbonates

Can be glued to themselves using solvent cements such as IPS Weld-On

The parts need to be aligned and held with a consistent joint. The adhesive is then flowed into the joint using an artist’s brush or syringe applicator.

Capillary action causes the glue to fill the joint.

PVC plastics can be glued together using common PVC cement available at any hardware store.

Styrenes and ABS plastics will bond together with common model maker’s glues from a hobby store.

Polyethylenes and nylons are impervious to virtually all adhesives and must be mechanically fastened.

Adhesives

•Plastics Distributors in the local area

•For small quantities, online sources such as McMaster-Carr are excellent.

•Plastic saw blades and router bits can be sourced from your current suppliers.

•Specialty hand tools, adhesives and strip heaters for plastics are harder to source if you don’t have a plastics distributor locally. Sources are in the handout.

Sources