With plexiglass, how to cut it may be a matter of the tools you have at hand. If all you have available to you is a circular saw, then that is what you will use. If, however, you have access to a table saw, using that tool is perhaps the easiest, most stable way to cut plexiglass.
Plexiglass is not glass. It is actually a type of plastic. With the heat that is generated by a power saw, it has a tendency to melt. To avoid this as much as possible, it helps to have the right type of blade and not to go too fast when making the cuts.
Step 1 - Measure the Plexiglass
Measure the plexiglass with your tape measure before you do any cutting. If the plexiglass is thin, using a table saw may be counterproductive as you might chip it severely. Thin plexiglass should be scored with a utility knife and snapped in two rather than cut. A ¼ inch thick plexiglass and up is safe to be cut with a table saw.
Step 2 - Choose the Saw Blade
Plexiglass comes in hard and soft varieties. Softer plexiglass may melt easier, so it is best to use a blade with fewer teeth to create less total friction as it cuts. Harder plexiglass, on the other hand, should be cut by a blade with more teeth in order to keep chipping to a minimum. If you have different types of plexiglass to cut, try to make all the hard cuts at once. Once you're finished making the hard cuts, do all the soft cuts at once. That way, you will only have to change the blade once or twice. A carbide tipped blade is best.
Step 3 - Measure the Size of the Cut
Measure the size you wish to cut and mark it on the plexiglass. When setting the fence on the table saw to hold the plexiglass in place, remember to compensate for the thickness of the blade so your piece does not end up too narrow. Lock the fence into place.
Step 4 - Use Safety Glasses
Safety glasses are always necessary when using the table saw, but especially when cutting plexiglass. Small shards of plastic can go flying, and you don’t want anything to end up in your eyes.
Step 5 - Make the Cut
Turn on the saw and slowly feed the plexiglass through the blade with one end held up to the fence. For very thin strips of plexiglass, make sure to use a wooden safety guide to keep your hands a safe distance from the blade. Go slowly. If chipping occurs, stop the cutting and change the blade to one with even more teeth. If melting occurs, slow down to reduce the heat.
Step 6 - Sand Edges
If there is any glazing on the edges due to melted plastic, sand it down with some fine grit sandpaper until it is as clear as you can get it. Sand down any splinters as well so the edge is smooth.
Using the table saw is the easiest way to cut plexiglass, but if you don’t have the tool available to you, you can use other power saws as well.