Tips for Drilling Plexiglass Acrylic and Polycarbonate Lexan:
For best results, clamp material to be drilled securely to a work bench or table. Placing a backing block of scrap acrylic, mdf, or plywood panel under the drilling point will add extra help to prevent chipping when the bit breaks through. Be sure to firmly chuck the drill bit in the cordless hand drills or drill press. When using hand drills, a slow speed setting works best with plexiglass and lexan. For drill presses, a slow speed is also recommended, but consult the manufacturer for the best settings for drilling plastics such as plexiglass acrylic and polycarboante lexan.
Apply a steady pressure while drilling the hole, and then reduce pressure just before the drill breaks through. Try not punch the bit through the material when almost at the end of the hole. This may cause chipping as the bit comes out the back side of the panel.
When drilling holes for screws and bolts in plexiglass and most other plastics, you'll need to make the hole larger than the bolt or screw to allow for expansion and contraction that occurs in the sheet.
Also, when considering hole placement, drill the hole or holes as far from the edge of the sheet that your project will allow. Avoid drilling holes closer than 1/4" from the outside of the hole to the edge of the sheet. The larger and heavier the sheet, the more distance you'll want between the outside of the hole and the sheet's edge.