Drilling plexiglass

[Dieselman 63]

My friend wants me to drill her some holes in plexiglass. I said I'd do it on my Fobco but apparently she said there are special bits, you can't just use HSS or it cracks/melts... is this true? I had a quick google but I wondered if anyone has experience with drilling it.

Cheers

 

[MattF]

Wouldn't flat tip bits, akin to the type used for tiles and such, be best for that task?

 

[W.olly]

After drilling all kinds of plexi/Acrylic/perspex many times for sumps in fishtank filters I found a blunt/non sharp HAS bit at a higher than normal speed is spot on. It will soften the plastic and not pull through itself.

I have done this on a few hundreds holes close to the edge (10mm) on 6mm acrylic recently. Not one breakage.

 

[JEZGUZ]

I've got a few of the special type bits for drilling plastics, they have a steep sharp point and a slow helix, if you google drilling plastics and look in images you'll see the type of drill bit, but as pdg wrote using a drill bit set up for brass should work. Use something like trefolex for lube. Have a practice on some scrap first though, just in case.

 

[pedrobedro]

Blunt HSS drills work, sharp ones cause splits when they break through. They have a special one for bike plates round at the shop.

 

[8ob]

We use the stuff on some of our machines, sound advice above but would add not to attempt doing anything with plexiglass unless its warm. I have found spotweld drills to be good for drilling close to the edge, as in the stump grinder screen below.

Bob

 

[Shox Dr]

Trapping the plastic between two sheets of ply or wood, and then drilling through the lot, stops it from cracking as well

 

[Maker]

Regrind it so the included angle at the tip is very sharp, about 60 degrees is probably about right. I drilled a 3mm hold into the edge of 5mm acrylic with this trick.

 

[Keith 66]

Grind a slight negative rake on the cutting edges of the drill or use a small diamond file. The drill will then scrape its way through cleanly with no breakout

 

[wookie]

Trapping the plastic between two sheets of ply or wood, and then drilling through the lot, stops it from cracking as well

That's my preferred method as well.

 

[the artfull-codger]

Pdq hit the nail spot on,as did kieth66 stone the cutting edges off a normal hss drill as for drilling brass & a steady feed & speed, no need for cutting oil clamping between ply or anything, better laid on wood in the drilling machine or if hand electric drill laid onto a piece of wood, I've drilled thousands of holes like that in acrylic,darvic makralon,polycarbonate & brass,I taught 11yr old kiddies in school that way & very few cracked the acrylic,if 11 yr olds can do it us grown ups won't have any bother.

 

[Parm]

I've just used regular drill bits from the box of regular drill bits. Slow n steady wins the race. Never had any issues. Plenty of holes made in various projects

 

[Dieselman 63]

Thanks for all the advice... it's pretty inconclusive though! I reckon the drill press would give a better cut. I think it'd be best if I did a series of tests prior to doing the real thing because you've all got different methods, slow, fast, blunt bits, tapered sharp bits :P

 

[Dieselman 63]

We use the stuff on some of our machines, sound advice above but would add not to attempt doing anything with plexiglass unless its warm. I have found spotweld drills to be good for drilling close to the edge, as in the stump grinder screen below.

Bob

That machine looks brilliant btw

 

[Ton-up]

If you think a normal sharp drill will do it, look at car number plates. The amount of plates with an area damaged or split around the screws that garage 'technicians' have fitted, will show you NOT to use one.

As others have said, back off the cutting face of the drill and it wont 'grab' as it goes through.

 

[Dieselman 63]

Job done. Flattened the end of a bit, rounded the corners and the flutes on the grinder. I used the drill at 4000rpm with a super slow feed. I got under half a mil of slight distortion in the glass which I consider perfectly acceptable. My friend was thrilled, so a happy result all round, thanks team!