Need some suggestions for drilling Plexiglas

[Steven J Corpstein]

I have a 1/4" thick piece of Plexiglas (not Lexan) that I need to enlarge an existing 1 1/2" hole to 3" without damaging the item. My choices of available tools are router or a 3" holes saw on a drill press. I realize that regardless of what I use, I need to make a template and take it slow. Anybody want to share their experiences?

[Bob Landel]

I like to think I'm a plastics expert. You are dealing with acrylic. Use the 3" hole saw. (A router would spin too fast.) Drill slow as you indicated and make, sure the template is centered held fine where you need it. If you are that concerned, practice on a piece of scrap. You should have no problem.

[Craig Michael]

One thing that is the best technique for drilling any plastic, fiberglass, etc. is to drill it in reverse for a little to develop a lip in the material. Often with hole saws the teeth grab quickly and create a situation where the bit takes off across the material. If you go in reverse the teeth are not aggressive and they can make a lip then you go in forward and finish off the hole.

Not sure how dead on this hole needs to be. Another trick for enlarging an existing hole saw hole is to put a plug from the smaller hole onto the hole saw with the 3" hole saw then use that as a guide for drilling the new larger hole. Just make sure the plug is a greater depth than the 3" hole saw so your plug lines up with the smaller hole before the teeth from the hole saw reach the plexi. (I'd still run the hole saw in reverse for a handful of rotations to get the groove then go forward)

[Todd Davidson]

Another vote for the hole saw with one of these: http://www.mcfeelys.com/product/HS-0...OOPSquot-Arbor.

[Don Orr]

Interesting but how does one get their drill press to run in reverse. Or are you talking about a hand-held drill ? 3" hole saw on a hand-held drill with no pilot hole is kind of unstable to me. Or am I missing something ?

[Jay Jeffery]

If you need to get it right the first time, I'd suggest sandwiching the material between 2 sheets of some sort of wood product. A hole saw is not going to work well without something for the pilot bit to bite into. I'd use plywood on the bottom and perhaps something thin like masonite on the top. A drill press would be the right tool for the job without question. If you must use a hand drill, make it one with a side handle and a slow speed setting. Be patient with the plastic and bring it up frequently to clear the chips. You can clean up the burs with a knife if you are careful.

Be aware that while cutting plastic may seem easy with woodworking tools, it can be very abrasive and dull them quicker than other materials.

[Mike Dodson]

I've had the best luck with a drill press and a circle cutter. http://www.rockler.com/product.cfm?p...ircle%20cutter Use the slowest speed on your DP and clear the shavings often.

[Craig Michael]

Interesting but how does one get their drill press to run in reverse. Or are you talking about a hand-held drill ? 3" hole saw on a hand-held drill with no pilot hole is kind of unstable to me. Or am I missing something ?

Not sure about how to run a drill press in reverse, my guess is you could rewire it to but I'm not sure. But yes, use a hand drill. 3" on a hand drill isn't anything difficult. All plumbers use 4" hole saws to drill the framing material to run the main plumbing stack, electrician's use 5", 6", etc. to drill for recessed lights, use 3" to drill for rough mount boxes for lights, smoke detectors, etc.

Whenever you are using the larger hole saws like that, use lower gears to protect the drill motor and just start off slow.



You could use the arbor Todd suggested. But you can do this http://www.finehomebuilding.com/item...2-18-inch-hole or instead of putting the smaller hole saw on, drill out a plug with the smaller hole saw and put that on the pilot bit of the arbor.

[Donny Lawson]

I've worked with plexiglass alot in the past. It is quite easy with a holesaw cutter in your drill press. Clamp a scrap piece of plywood to your drillpress table and center your plexiglass where you want the hole. Clamp it to your plywood. Run your drill press around 1000-1200 rpm. Take "slow" cuts. Basically scratch the surface with each pass. As long as you go "SLOW" you will not have a problem. If you go too fast the plexiglass will start to melt and you might get a catch and crack the edges.
Donny

[Rick Whitehead]

Here's another idea. Use the hole saw to make a hole in a piece of MDF or plywood.Locate and clamp that over your hole to be enlarged, and use a router bit with a top bearing to rout the hole.
The hole saw will leave a rough edge in plexi, so the router will leave the smoothest edge.
I have used this technique before to enlarge and re-shape holes in plexi.
Rick W

[Phil Phelps]

It's best to know if it's cast or extruded before drilling. You can use Rick's method for best results on either. Cell cast acrylic is much more heat tolerable. When using regular wood working drills and saws, extruded acrylic will melt and leave a rough edge. This is much more noticable when using drills and jig saws. When ever I'm forced to use a hole saw on extruded acrylic, I will make several plunges, about 1/16" with the drill press, allowing a little cooling time between cuts. I also wax the teeth of the hole saw. Cell cast is more expensive and has red lettering on the paper. Extruded has blue lettering on the paper masking. They both cut well with carbide blades, but drilling is another story. There is a lot more to properly working with the two acrylics. Again, go with the router.

[pat warner]

Send to me, can manage gratis.

[Rich Noterman]

Check with a local awards engraver that has a laser engraver they can cut it and will be nice a smooth wont have to sand it.

[Steven J Corpstein]

For anyone that is interested, I got my hole done in what turned out to be Lexan. I made a template that had a raised 1 1/2" pilot (so to speak) to center my existing hole on. Then I just used a router and took small amounts off by using PC collars in the template and allowing adequate cooling time so the plastic wouldn't melt and grab. The finished hole was dead on, and the edge was very smooth.

[Bob Landel]

I should say polycarbonate melts at a higher temp than acrylic and therfore easier to drill. I still don't like the idea of using a router on any plastic. I think the rpm's are too high and create too much heat during fabrication.