When you cut Plexiglass with a jig saw, the plastic that?s been cut away often melts and closes the cut line behind the saw. Richard from Guelph, Ontario saw me struggling with this and suggested adding motor oil to the surface to lubricate and cool the scrap -- it does work.
Probably most important is to realize that the blades for cutting metal and plastic come with different sizes of teeth. The fine teeth are for thin plastics that would chip with a larger tooth. But if you use the fine tooth in a thick plastic, everything starts to melt. Using larger teeth for thicker plastic will clear out the shavings more efficiently and reduce the heat, and hence the melting. Add the oil and everything comes out clean. Thanks Richard.