Cutting Lexan

[Bill Orbine]

I'm looking forward in doing a project for a customer of mine. This project is building a cover for an approximate 45" x 75" basement window well. Some of the priorities is that the cover be hinged for access and fire escape, allow light to filter through, be safe that no sharp objects can injure (like broken glass) as well as the top priority is to direct rain water away. I'm thinking Lexan or polycarbonate is the suitible material for a sloped cover. I've worked with acrylics before, but not polycarbonate. Is a table saw and/or vertical panel saw Ok to use? Router? I'm thinking of cutting slightly oversize and then clean up with router. How about drilling? What types of drill bits is safe to use? Any help here will be greatly appreciated. Thanks.. Bill

[Tom Veatch]

It may be that God looks out for fools and drunkards, but I recently built a transparent router base out of 1/4" Lexan, and treated it just like wood. Band sawed it to rough shape, routed it to final shape with a flush trim bit. Drilled mounting holes with a regular twist drill. Don't know if it was a 118° or 135° point - I have both lying around. Bored the center clearance hole with a Forstner bit. No issues, no surprises.

Repeating myself, I treated it no different than if it had been a piece of plywood, and it worked fine. I have a piece of 1/2" Lexan I'm going to use to make a mortising jig when I finish the current job. Based on previous results, I don't expect to have to do anything special to machine it.

[Shiraz Balolia]

I'm looking forward in doing a project for a customer of mine. This project is building a cover for an approximate 45" x 75" basement window well. Some of the priorities is that the cover be hinged for access and fire escape, allow light to filter through, be safe that no sharp objects can injure (like broken glass) as well as the top priority is to direct rain water away. I'm thinking Lexan or polycarbonate is the suitible material for a sloped cover. I've worked with acrylics before, but not polycarbonate. Is a table saw and/or vertical panel saw Ok to use? Router? I'm thinking of cutting slightly oversize and then clean up with router. How about drilling? What types of drill bits is safe to use? Any help here will be greatly appreciated. Thanks.. Bill

Be extremely careful when cutting Lexan type polycarbonates on a tablesaw. Make sure your splitter is in place, as well as all guarding, and do stand to one side (out of missile launch range) as you are cutting. Use push sticks.

All it takes is a split second and the kick-back with a broken/shattered polycarbonate can have life altering consequences.

[george wilson]

To drill holes in plastic,grind the cutting edges of the twist drill vertical. 1/32" of vertical grind will do. The drill then will not be pulled through the plastic sheet as it breaks through,shattering the plastic. I have subsequently used the altered drills on steel just fine. The drills also are excellent for use on sheet metal and BRASS,which is treacherous to grab as a normal drill breaks through. I cut myself fairly badly years ago when a block of brass I had CLAMPED IN A DRILL PRESS VISE pulled right up out of the vise as the bit broke through. Then,the square corner of the brass block was sharp enough to really lay my finger open. It took about 15 years for feeling to return to the pad of my finger. Guess the nerves finally found each other.

[johnny means]

I work with quite a bit of Lexan and it can be tricky to get a clean edge. First of all use a sharp blade, preferably one with a negative hook. Watch your feed rate. Too fast and it chips, to slow and the melted material will gum up in your throat plate kerf. Splitters can be a problem sometimes, as the hardened "sawdust" sometimes gums up in the kerf.

If possible use a flush trim bit to trim to final size/shape. Once again, sharp.

If you need a polished edge brush over it with a MAP gas torch after sanding to about 180 grit. Practice this on scraps first, as it takes a certain touch and speed to not yellow the edge, yet apply enough heat for a polish.

When drilling, do not let the bit stop turning in the work piece. It will get stuck when the melted Lexan hardens in your drill bit flutes. I snapped off plenty a bit with this particular mistake.

Most importantly, leave the protective film on until your done.

[Conrad Fiore]

Bill,
I have owned and operated an engraving and plastic fabricating shop for over 40 years. Polycarbonate is no more difficult to machine than acrylic.
We use triple chip grind plastic cutting blades on our table saws and cut material thickness from .032" to 1.0" without problems, no chipping, no cracking or melting. It helps to split the drill point to lessen the chance of the drill grabbing in thicker stock. If you are going to be doing multiple operations to the material, my most important tip is to get the material PAPER MASKED, not film masked. The film masking comes off to easily and polycarbonate is much softer than acrylic and will sctatch just looking at it.