Drill bit for polycarbonate sheet

I've a need coming up to drill a dozen or so holes for screws in 2mm solid polycarbonate sheet - say 6mm holes for 4mm screws. But what drill bit should I use? Suggestions based on experience would be especially welcome as the internet has already given me a confusion of advice.

Some sites suggest special drill bits for plastics which I wouldn't mind buying if necessary, but they don't seem available locally/cheaply.

Some say that wood bits can be used - but don't say what kind of wood bit; and the Wiki[1] hints that my wood bits might not be the best thing.

OTOH some say high speed metal and multimaterial work. Or that high speed should be reground - which would be an adventure I'd rather avoid.

Oh, and I'd be doing this with handheld drills, not a press.

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Reply to
Robin
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When I drilled some twin wall polycarbonate for the Succah, I just used a lip and spur wood bit.

I'm interested to read that "Lip & Spur bits don't drill metal or most plastics." I did not know this, and neither did the plastic or the drill! It seemed obvious to me that a drill bit with a nice sharp point at the front would be 'a good thing'. :)

The plastic is quite fragile, so just take it very easy. Perhaps experiment on an off-cut.

Reply to
GB

I'd say you need a sharp and accurate drill as used for metals. Definitely not a wood drill.

Fast is OK if you can keep the pressure down, as you might do in a drill press, but with a hand or cordless drill you want slow speed to avoid melting.

I'd use my cobalt drills but if you only have a normal HSS set they should be OK.

Practice on scrap, if you have any.

Reply to
newshound

Lots of conflicting advice here because there's more than one way. The plas tic is prone to cracking as a drill bit grabs. The truth is you can drill p lastic with any bit in principle, even a completely blunt masonry bit. What differs is the required technique & the risk of breakage.

Standard hss twist drill bit with hand drill: these grab badly, so use /ver y/ low pressure & high speed. Melting is not a problem, indeed it's safer t o melt through than cut. The deal with melting is that once the bit is thro ugh it must be withdrawn without any delay, otherwise the bit jams in the r esolidified plastic and removing it then can cause breakage.

There are lots of other ways. If that's what you have, use it. I prefer a s tone in a dremel, it melts through with close to zero risk of breakage, as long as it's withdrawn without delay.

Lip & spur bits can work, but if the point is not sharp they're rather slow er to get going.

NT

Reply to
tabbypurr

Standard HSS drill. On a slowish speed to prevent heating things up. Make sure it is good and sharp. Best to drill a pilot hole first. If lots to do, two drills are then handy.

Reply to
Dave Plowman (News)

Standard HSS drill but keep the pressure VERY low.

Bill

Reply to
Bill Wright

Yes micro cracks have a habit orf spreading if the plastic is subjected over time to outside temperature changes. Also, I did a pretty neat one off job with a face mask, for the pong and an old soldering iron..:-) Brian

Reply to
Brian Gaff

Bill Wright wrote in news:pqkotm$1pr4$ snipped-for-privacy@gioia.aioe.org:

I would be inclined to grind the bit to reduce the rake angle - but that may be hard to do if not used to grinding bits (Ex- Jig Borer)

Reply to
DerbyBorn

Thanks to you and others for all the tips.

I'll pass on grinding bits as (for this ex paper-pusher) drilling polycarbonate is enough of a learning experience for the present. The more so as I'll have no scrap to practice on having ordered cut-to-size.

Reply to
Robin

I have recently had good results drilling small diameter ( 2 or 3 mm ) pilo t hole, followed by using a new (sharp) HSS bit using a drill/driver set in low-speed mode with low pressure, and the minimum possible torque that all owed the drill to rotate. I got nice spirals of polycarbonate, indicating n o melting. If the drill 'grabbed', a bit of reverse followed by restarting worked fine. This allowed me to drill 8 holes in more than 10-year old old polycarbonate caravan windows. Chamfered the edges of the holes with a coun ter-sink bit which allowed me to bolt together (with some large washers) th e two panes of polycarbonate where the glue had failed (an old manufacturin g fault*). In good D-I-Y spirit, it saved me the cost of several caravan wi ndows as the safety recall has expired (before I became responsible the mai ntenance of the said caravan).

Sid

*Apparently, lots of caravan windows manufactured by a particular Dutch fir m and resold across many caravan builders had a problem where the layers wo uld delaminate, potentially allowing sheets of ploycarbonate to fly off as the caravan was being towed. Hence the safety recall.

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It is not limited to those makes (I did the repairs on a Bürstner).

Reply to
unopened

lot hole, followed by using a new (sharp) HSS bit using a drill/driver set in low-speed mode with low pressure, and the minimum possible torque that a llowed the drill to rotate. I got nice spirals of polycarbonate, indicating no melting. If the drill 'grabbed', a bit of reverse followed by restartin g worked fine. This allowed me to drill 8 holes in more than 10-year old ol d polycarbonate caravan windows. Chamfered the edges of the holes with a co unter-sink bit which allowed me to bolt together (with some large washers) the two panes of polycarbonate where the glue had failed (an old manufactur ing fault*). In good D-I-Y spirit, it saved me the cost of several caravan windows as the safety recall has expired (before I became responsible the m aintenance of the said caravan).

irm and resold across many caravan builders had a problem where the layers would delaminate, potentially allowing sheets of ploycarbonate to fly off a s the caravan was being towed. Hence the safety recall.

Of course, now that I looked again, I find the official recall for Bür stner caravans. Sigh.

Reference on the Driver and Vehicle Standards Agency site is RSPV/2008/009

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or just use BURSTNER in the drop down list for "Make:" on this page

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Reply to
unopened

You could do a lot worse than Brian's suggestion of an old soldering iron.

Reply to
GB

Just wondering - no material on which to test - if a spade-type tile drill would do it.

Reply to
PeterC

Practice on a CD case? Polycarbonate, AFAIK, and thin and grabby, also plentiful and cheap.

Thomas Prufer

Reply to
Thomas Prufer

No. polystyrene.

Polycarbonate is expensive because it doesnt crack very easily. Styrene is cheep....

and thin and grabby, also plentiful

Reply to
The Natural Philosopher

Melting can be a problem with thicker material. I wouldn't expect it to be an issue with 2mm sheet though. Brittleness and snatch are the main risks. That is why I would clamp it fairly carefully for support.

The main thing is clamp it well. Plastic sheet is inclined to snatch as you break through and the entire job going round can seriously damage anything that gets in its way. I'd use an HSS metal drill and drill through the material into a wooden block supporting it. Practice on scrap first and keep an eye out for molten plastic accumulating on the cutting edge if you try to cut too fast.

Reply to
Martin Brown

In message , Robin writes

A little late, but I will endorse the ordinary HSS drill bit comments, but at a slow speed, and without too much pressure.

I recently drilled quite a lot of 10mm holes in 2mm (or possibly 3mm) clear plastic sheet, and none caused any damage. Too fast, and the plastic will melt. I clamped the sheet plastic to a firm wood surface, to give support behind, and drilled through the plastic into the wood.

Just in case you need to trim, the sheets I was drilling were 96 x 12 inches, but some I had to reduce the length, so scribed a cut line with a Stanley knife, then cut with a fairly fine toothed Tenon saw. Again, no problems, but do provide adequate support both sides of the cut line, and go firmly but slowly.

Reply to
Graeme

Then drill using several sizes of drill - smallest first. Less chance of cracking then.

Reply to
Dave Plowman (News)

I endorse this. I forgot to point out I had a scrap wooden block clamped fi rmly behind the polycarbonate, which itself was well fixed.

Sid

Reply to
unopened

The other thing that is tricky for a novice and a handheld power drill is that when trying to drill a shiny material the drill may be inclined to skate around rather than go where you want it to start the hole.

On metal you would centre punch the hole to prevent this skating but that option isn't available on brittle plastic. Starting the hole centre with a manual sharp pointy tool or small drill might be wise. It is quite easy to end up putting a long scratch on the material by accident.

A 3-4mm pilot hole might be helpful - that way if drifts off centre you can recover it by manually by filing with some needle files.

Reply to
Martin Brown

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