Drilling & Sawing Tips For the Home Fabricator

Posted: June 8, 2015 in machining
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Plastic fabrication questions come up often with “Do it yourselfers”. The public is less familiar with working with industrial plastic compared to wood or metal and wonder what changes need to be made. The answer? Not much.

Drilling & Bits:

For plastics solid carbide, carbide tipped and high-speed steel are most commonly used. Of the the three, carbide tipped (note the difference from solid carbide!) would be the closest thing to an “all-around” bit as it offers an excellent finish with the strength of the steel core. Jarring motions and general inconsistencies working by hand means that solid carbide bits should be avoided.

Bits come in both “O-flutes” and “V-flutes”. The V-flute is better for harder plastics such as Micarta, industrial laminates, acrylic (cast). The O-flute would be better for your polyolefins (UHMW and HDPE in particular), extruded acrylic and polycarbonate. In general, the more cutting edges you have, the better as this can make your inconsistent and amateur (no offense intended) feed rates more forgiving. Higher speed drills or routers will create a better finish and a smoother action.

Sawing & Hardware:

Similar to drilling or routing, carbide tipped blades and high RPMs are best for sawing plastics. Otherwise, they cut similar to wood. Like wood, you may need to do some light sanding on the edges after cutting to deburr the plastic. Customers seem to be especially intrigued by the smooth, glass-like surface finishes in many finished acrylic products they see for sale. However, you need to know that acrylic does not finish like this with regular fabrication at home. You will need to obtain a torch and teach yourself how to flame-polish the acrylic, or use a chemically-based flame-polishing alternative. Both options have short tutorials readily available on YouTube by the “DIY” crowd (note: of course Redwood Plastics does not recommend or endorse any particular video).

We also get asked a lot about particular hardware for plastics. Unless it’s M-Clips or bolts for FRP grating then there really isn’t any special hardware for most industrial plastics applications you would be working on. It’s important with plastics you’re using outdoors to oversize the holes by 1/8″ to allow for thermal expansion and contracting using washers is key to not place too much stress on the plastic, which could cause warping.

do-it-yourself

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