How to Cut Plexiglass with a Router
If you don’t have one of several types of power saws available to use, if you have a router, it is possible to cut plexiglass with it. Provided you have the correct blade designed to make a flush cut, a variable speed router, when done right, will cut plexiglass. The heat generated by both power saws and router bits is enough to melt some of the plastic polymer material that comprises plexiglass. This can have the effect of glazing the cut edge of the plexiglass, reducing its transparency. By making the cut steadily and by making a rough pass followed by a finish pass, this can largely be avoided.
Step 1: Set Up Work Area
Ideally, you can set up the piece of plexiglass at a raised level so the blade is allowed to pass between and not come into contact with the work table. You still have to clamp down the plexiglass, though, preferably on both sides. If you can rig up a fence so the router is forced to go in a straight line, that would be helpful too.
Step 2: Draw the Line
Covering both sides of new plexiglass is a brown paper film that is removable. On it you can draw the cut line with the help of a straight edge.
Step 3: Position the Plexiglass, Fence
Clamp the plexiglass into place and set up the fence (if you have one) to one side of the line to be cut. Routers are moved towards you when they work, so it would be best to set up the fence on your side of the line.
Step 4: Prep the Router
Open the collet of the router and replace the blade with a 2 flute carbide router bit. This bit reduces vibration when cutting and makes a smoother, flush edge. Tighten the collet and make sure the router bit is perfectly set with no rattle.
Step 5: Set the Variable Speed
Your router should have at least 1.5 horsepower and come with a variable speed setting. Set it to the slower speed. The faster the bit rotates, the hotter it gets. This will increase the chance of melting the plexiglass.
Step 6: Keep the Router Straight and Steady
If you don’t have a guide fence, it is important that you keep the router straight as you move it along the line. Plan on making a rough cut first. When the router is turned on, move it steadily as well. Don’t spend too long in one spot or else the polymer will heat up.
Step 7: Finish the Edge
After the plexiglass is in 2 pieces, run the router again over the piece you are using to put a better finish on the edge. Follow this with fine grit sandpaper to smooth out both the face and the edges.
If a router is the only tool you have available to use to cut plexiglass, provided you have the right bit and the skill, you can make the cut almost as easily as with a power saw.