? clean holes in plexiglass???

[Norris Randall]

Greetings Ladies & Gents,
I am having difficulty boring holes in 1/8 " plexiglass.
Would prefer same thickness as 25 cent piece which is a little thinner.
The project requires 25 clean holes 1" in diameter in one piece of material.
Actually a little smaller would be ideal since I want quarters (.955 in.)to fit in the holes.
I've tried spade bit, forstner bit & hole saw.
They all seem to melt a little around the edges and leave a rather rough finish.
I have tried to use a slow "feed" with out any improvement.

All suggestions appreciated.

The finished project will have a WOODEN frame. so this should qualify for this forum :D

[Larry Browning]

I don't know if this helps, but you can buy a drill bit designed for quarters.
http://www.rockler.com/product.cfm?page=6401
(http://www.rockler.com/product.cfm?page=6401)
I am interested in seeing the answer to this as well. I had the same problem when making the door on Norm's router table.

[David Hawxhurst]

if you debur the edges you can polish them with a propane/butane torch.

[Bill Wyko]

Sharp unibit. Works like a charm.

[Dan Hintz]

Or if you need a lot of them, find someone local with a laser. We can do stuff like that in a heartbeat, and the edges are nice and clear.

[Norris Randall]

Well, I came back to this thread; but now do not see the suggestion that I tried.
Where ever the suggestion came from it seems to have worked.
"Try lexan" it will cut with long continuous "curls". I picked up a small sample
and drilled a 1" hole. Soothe edges and ONE long curl. If anything changes I'll post it here.

[Joe Pfeifer]

If it's melting try a slower bit speed while feeding with steady pressure.

[Andrew Kertesz]

#1 on Dan's suggestion of using a laser. If you can find someone local you will not be able to match the accuracy and the clean cut on the holes. The laser polishes the edges as it cuts.

[Trevor Walsh]

Slow the speed down a bunch, a forstner will do it, also slow the feed down when reaching the opposite side.

[David Hawxhurst]

Well, I came back to this thread; but now do not see the suggestion that I tried.
Where ever the suggestion came from it seems to have worked.
"Try lexan" it will cut with long continuous "curls". I picked up a small sample
and drilled a 1" hole. Soothe edges and ONE long curl. If anything changes I'll post it here.

while lexan is a trade name (for polycarbonate) it is much easier to machine (drill, route, etc) then plexiglass (which is also a trade name).

[john lampros]

When drilling plexi we always use a soapy water spray to get clean holes, it lubes and keeps the edges from melting, they should come out almost glossy. if not, slow down the press.

[Bill Wyko]

You can't cut Lexan with a lazar though, it'll burn it. Plexi no problem though.