Working Plastics in the Woodshop; More isn’t always better.

17. April 2018 11:57

By Ralph Bagnall, Woodworking Consultant, Author and TV Host: Consulting

Most wood shops rarely use plastics, and typically don’t have specialty blades designed for plastics on hand when they need to cut just a few parts for a project. Common woodworking blades will cut many plastics with suitable results, but which blade should you choose to cut with?

The woodworker’s first impulse is usually to use a fine toothed plywood blade of 80-90 teeth. It sort of makes sense; sheet plastics are often brittle, and we want the blade to cut with a minimum chance for chipping, so more teeth would seem to be the right choice. What is generally not understood is that heat is a far more important factor than impact stress in achieving a clean cut in hard plastics. Put simply, the more teeth in contact with the plastic, the more friction is allowed to heat the kerf, and the more likely the material will melt rather than cut.

It seems counter-intuitive, but a 50-60 tooth high ATB combo blade is a far more effective tool for cutting hard sheet plastics. The sharp points of the teeth score and define the edges of the cut before removing the waste  and the large gullets between the teeth keep the kerf sides from overheating through friction. Your cut will be better. Try it and see for yourself.

For more information about blades and bits cutting plastics, sign up for Session MFG7; “Working Plastics in the Woodshop”.


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