When cutting Plexiglas you need Lucite L or an equivalent, some of the other types will not cut well without melting back together because of the manufacturing process used to make them. Also leave the protective paper on or replace it with masking tape as it helps to cool the cut from melting back. The best speed is 1000 or slower and my favorite blade is the double skip tooth design by Olson, using the #5 size for most cutting. In Spielman's Home Workshop News it is suggested that you grind or file the back of a #9 blade so there is clearance behind the teeth to keep the heat down. I have tried that and it does work to a point, but I have also found that the cut is a little rough with the #9. Another way is to use the #5 I like and round the blade in the back. That helps some, but by putting layers of masking tape on the bottom of the plastic it seems to help more. I tested this by leaving the protective paper on the plastic and then putting layers of masking tape on the bottom. By stair stepping layers of tape to 3 layers I have found that each layer of tape added decreases the chance of the plastic melting back together. As I cut across the plastic and hit the areas where the tape was placed the cut became smoother as the layers of tape increased and the melting back became less with each layer. For some reason the tape absorbs the heat of the blade and discourages the melting back. So try some test cuts on your plastic with multiple layers to find the one you like best. It has now been proved that the clear packing tape will work just as good as the masking tape. So you have two choices to use.
Another way to cut Plexiglas is to use a lube as you cut. I've heard of using water, to WD-40, to the blade lube sticks, and even beeswax. They all seem to work but they all seem to make a mess on the saw table and the Plexiglas that you need to clean up. And if you are mounting photographs to the plastic to cut out, the lubes are real hard on the photos. Cutting out photos so just the subject (person, dog or car, etc.) is left and all the background is gone then mounting them standing on a base can be a lot of fun.
I have received an e mail from Jerry Vis. A few more hints on cutting plexiglas. If you have an air compressor, mount a small tube and valve to your air supply on the saw. Use the valve to adjust the air flow to cool the blade, but not blast the shavings all over. The air blowing on the blade cools the blade and helps by keeping the plexiglas from melting back together.
Another method from Jerry says use Mazola cooking spray oil. It works best if the blade is hot before applying it on the blade. When the plexiglas starts melting again just re-apply more Mazola to the blade.
Another scroller, Rob Brady, just informed me that Dove dishwashing liquid is also a good lubricant/coolant for cutting plexiglas.
He states that both of these tricks work great when drilling into plexiglas too.
----- Original Message -----Sent: Wednesday, September 15, 2004 12:28 PMSubject: Cutting Plexiglas tip
I was reading your tips on cutting Plexiglas. I use 1/8" Plexiglas on all my inlay art glass panels. Fusing was initially a problem and I tried most of the tips you described. I used the duct tape method for a while. Even though it works great, it was too slow for me. Now, I rub the pencil cutline that is drawn on the protective paper covering the Plexiglas with a regular white candle. This place a thin wax line atop my cutting line and prevents fusing by contaminating the molten plastic. It has worked really well and it doesn't require any cleanup.Regards,Glenn