drilling plexiglass

I'm making up a control panel (actually several if this one works) which is thin plwood or masonite with a computer-generated diagram glued to that and a non-glare plexiglass cover.

I have to drill the plexiglass for the switches and lights. Doing a google, I've seen claims that you need special bits, others say just drill slowly, others say masking tape solves the problems, etc..

Since I'm also a woodworker, I have twist bits, bradpoint bits, Forstner bits, and even a spade bit or two. I just don't know which, if any of them to use :-).

Any voices of experience on the subject from this group?

Use a drill press if you have one. Some tape to keep the bit from skipping around. And go slowly drilling in plastic.

...Bill

My old control panels were constructed like you described. I found that a dull machine bit going medium speed worked the best. A sharp bit will grab and crack the Plexiglas. I had an 8x10 panel that I had to drill 25 holes in and it was a major sweat until the last hole made it. Jim

On Tue, 15 Jul 2003 16:45:26 -0700, I read these words from Larry Blanchard :

Several of the above suggestions .............

1) Use masking tape to prevent the drill "skidding" and marking the surface. (This also works for car (auto) body paintwork) 2) Drill slowly !!!! Use a hand drill or a *very* low speed electric. (Otherwise it "melts" the plexiglass) 3) A drill for tile / glass works as does a *new* HSS bit (for metal) as both types tend to have *SHARP* points.

"Sharp" and "Slow" appear to be the critical factors.

-- Ian S

Think the three "S's"

SCRAP on which to practice.

SLOW, in a drill press run very slowly, less than 500 RPM

SHARP, as in brand spankin' new drill bits (note plural). HSS is fine, but use 'em for no more than 5 holes each.

-- Jim McLaughlin

**************************************************************************** **************************************************************************** I am getting really tired of spam, so the reply address is munged. Please don't just hit the reply key. Remove the obvious from the address to reply. **************************************************************************** **************************************************************************** Special treat for spambots: snipped-for-privacy@ftc.gov, snipped-for-privacy@ftc.gov, snipped-for-privacy@ftc.gov

My Black & Decker battery electric screwdriver (not a pistol type drill) works very weel drilling plastic, nice and slow

I use a drill press very slow and very light pressure. Use a substantial piece of wood backing to support the plexiglass. Drill right through into the wood a bit. Masking tape helps locate the drilling point.

Dave in GA.

My best results have been using forstner bits in a very slow drill press, with pilot holes drilled large enough to prevent the center spur in the forstner bit to bite.

I have drilled everything from 1/8 " polycarbonate to 1" polycarbonate (lexan), as well as 1/8 to 1" acetate.

Retract the bit often and clear the cuttings.

And a seldon mentioned thing is never drill or cut cold material, warm it to about body temp.

John H.

For the final word on how to drill, cut, and machine acrylics, go to cyro.com. They are a leading manufacturer of acrylics, and have an extensive technical library that will inform you as to the proper drill bit, bit rpm, and feed rate. Using the information from their site, and the proper drill bit, I successfully drilled over 200 holes in an acrylic sheet. Also, you may want to consider using an acylic sheet that has an anti abrasion coating on one side.

Just a thought, why not make a nice printed panel then have it laminated. Punch the required holes in it and then glue to the masonite etc. backing.

Peter

You can drill acryllic (plexiglass) with ordinary twist drills. if = your'e careful.

1) Don't push the drill too hard and add some lubricant (liquid soap = should do it!) you could put in a smaller "pilot hole" but no larger = than half the final diameter required. Too close to the finished size = and the drill will "snatch" 2) Hold the acryllic down firmly on a flat surface, the acryllic will = want to "ride"=20 up the flutes of the drill as it breaks through. If you can, clamp the = plastic down as close to the drill point as possible. 3) Make sure there are no holes or voids under the point the drill will = break through as this will cause the drill to "snatch" and "ride" up the = drill again. HTH

Daniel A. Mitchell wrote in article = ...

Step drills are excellent for any plastic but they usually start at 6mm = and graduate up; mine has 2mm steps. Above 18mm they tend to be = expensive. You could also use a cone cutter but this leaves a tapered = hole. Forstner bits do work up to about 50mm but are a bit messy (but = if you dissolve the swarf in Plastic Weld you get a great gap filling = glue for acryllic). If your'e using a drillstand the precautions I = mentioned before should work OK if your'e using a hand drill run it at a = slow speed and evrything should be OK. If you want to regrind your = drills see if you have any that have been "cooked up", these are likely = to be useless for metals already so if you make a hash of the grinding = its no loss and they should still be hard enough to drill plastic.

While a drill does not have to be very hard to drill plastics, they have to be quite hard to KEEP drilling plastics. That is, if you need to drill a LOT of holes don't start with a poor drill or one that's been 'cooked' (unless you intend to resharpen it often).

Strangely, most plastics are VERY abrasive ... they dull common tools far faster than machining most metals. Carbide is often used to machine plastics for this reason ... wear resistance is important for sustained use.

A lubricant/coolant suitable for plastic can also help ... water works fairly well. Avoid OILS, these can cause the plastic to break down ... often long after the hole is drilled. Oil causes acrylic ("Plex") to craze and crack around the hole.

Dan Mitchell ==========

Les Pickstock wrote:

...

graduate up; mine has 2mm steps. Above 18mm they tend to be expensive. You could also use a cone cutter but this leaves a tapered hole. Forstner bits do work up to about 50mm but are a bit messy (but if you dissolve the swarf in Plastic Weld you get a great gap filling glue for acryllic). If your'e using a drillstand the precautions I mentioned before should work OK if your'e using a hand drill run it at a slow speed and evrything should be OK. If you want to regrind your drills see if you have any that have been "cooked up", these are likely to be useless for metals already so if you make a hash of the grinding its no loss and they should still be hard enough to drill plastic.

LOL, John!

My method is to start with a 1/16" drill, then go to 1/8", then go up 1/8" at a time. Anything over 3/8" I get to 1/8" for a pilot hole, then use a spade drill. Using a spade drill makes a drill press a necessity, since it must be kept perpendicular to prevent digging in. I also use the old woodworker's trick of drilling half way in from each side, rather than all the way thru in one shot.

Walt

In article , snipped-for-privacy@fastmail.fm by Larry Blanchard dropped his wrench, scratched his head and mumbled,

You might want to try something like this if the plexiglas isn't too thick:

Bob

The company I used to work for made firealarm panels in much the same way....the only difference is I might have had 100 or more holes to drill in a single sheet.....Over 4 years and hundreds of panels, I only cracked one (cause the holes were too close together)

Here's the tricks....

First....leave the paper coating on the plexi until after you are done drilling. Some of the mfg use a thin plastic...take it off the side you are drilling...it only gets in the way.

We used a drill press on a medium speed, the table of the press was covered in particle board then that was covered by another plastic (sintra) that we used...The sintra helped, but was not essential. The thing you have to do first is drill a small pilot hole (1/16"~3/32") then drill slowly but smoothly with the HSS or bradpoint. On holes over

1/2" we used a step bit. Be careful as when the drillbit breaks thru the far side of the plexi, it will tend to chip a bit around the edges if you are pushing too hard. Try it on a few pieces of scrap first to get used to the cutting pressure..

Remember, let the bit do the cutt>

That works OK (sometimes) for thinner plexiglas and small holes, but not for bigger (are you sure you didn't have styrene or acrylic?)

Thanks for all the suggestions folks. Naturally you didn't all agree , but I think I got the general idea. I'll let you all know how it turns out.