Doing Things Wrong

Cutting Plastics

Cutting plastics presents a special problem in that many plastics generate significant heat and can melt. This is especially a problem with clear plastics and thicker materials.

Often you'll find that the material simply melted in front of the blade and re-solidified behind it, so you haven't actually made a cut, more like a weld. In this situation, if you pause cutting, the blade will become trapped in the material. Then you have a real problem.

Jigsaws blades heat up very fast in almost any material and are especially a problem in plastics.

The long blade on a band saw makes a good heat sink and is fairly resistant to heating, but thicker materials are still a problem. Even if the blade stays cool, the material can still melt around it.

Most scroll saw blades heat up pretty quickly and give the welding effect I described. For cutting plastics with a scroll saw, use a "skip-tooth" blade. This is a blade that looks like every other tooth is missing, and is much more resistant to heating. They are seldom labeled as such, just look in the package for what I described.


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Here is a terrific little saw handle that takes Sawzall blades. It comes with an array of blades, including the dangerously sharp flush-cut and rather dodgy drywall blades, and a few others that I've long since used up, but it will fit any Sawzall blade. But what really makes this thing great is when I started making my own blades - all the small ones along the right. I cut these from much larger Sawzall blades that I bought, using an angle grinder, and shaping them on the bench grinder. Sawzall blades all cut on the pull stroke, but as you can see, two of these blades cut on the push stroke, because I cut them reversed from the parent blade. The tangs are easy to make. Push blades are good for cutting through finished or laminated surfaces. These little blades give me a hand-held jigsaw, very useful for many loothery tasks. This saw is a Craftsman, so you better hustle on down to your local Sears and get one before it closes. Mine is on the death list. StewMac should pick up this idea.

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