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Keep Your Cool

by Editor 12. August 2018 17:58

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


There are many factors that need to be accounted for when cutting or milling plastics, but your over-arching concern should always be keeping things cool. With wood products, heat is an issue, but is secondary to vibration. With plastics it is the other way around; vibrations need to be controlled, but heat build-up is really the major concern. Too much heat begins to melt the plastic rather than cutting it, and this not only produces a poor edge, but the softened material can actually cool back in the kerf and weld itself together.
 
The heat we are concerned with is from friction. Every tooth cutting into the plastic generates heat, so generally, fewer teeth is better. Good gullet distance between teeth gives some chance for cooling between impacts. The diameter of a 10” saw blade generally lets the teeth cool between cuts, but if there are too many teeth, heat will build up along the cut line of the material.
 
With softer plastics like polycarbonates or nylons, a bandsaw blade removes heat from the cut line well but, again, large gullets and a healthy set to the teeth are recommended. Reciprocating blades like those on a jigsaw should not be used; the blade generates even more heat on the return as on the cutting stroke and allows no time for cooling. When cutting plastics, watch for galling around the kerf line, little bits of melted material clinging to the edges means the friction is excessive.

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