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.

[1] http://wiki.diyfaq.org.uk/index.php/...Spur_Wood_Bits

--
Robin
reply-to address is (intended to be) valid

On 22/10/2018 11:37, Robin wrote:
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.Â* But what
drill bit should I use?Â* 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.Â* 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.

[1] http://wiki.diyfaq.org.uk/index.php/...Spur_Wood_Bits


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.

On 22/10/2018 11:37, Robin wrote:
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.Â* But what
drill bit should I use?Â* 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.Â* 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.

[1] http://wiki.diyfaq.org.uk/index.php/...Spur_Wood_Bits

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.

Robin Wrote in message:
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.

[1] http://wiki.diyfaq.org.uk/index.php/...Spur_Wood_Bits


I just used a standard
HSS bit. Had no problems.
--
Chris French

On Monday, 22 October 2018 11:37:27 UTC+1, Robin wrote:
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.

[1] http://wiki.diyfaq.org.uk/index.php/...Spur_Wood_Bits

Lots of conflicting advice here because there's more than one way. The plastic is prone to cracking as a drill bit grabs. The truth is you can drill plastic 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 /very/ low pressure & high speed. Melting is not a problem, indeed it's safer to melt through than cut. The deal with melting is that once the bit is through it must be withdrawn without any delay, otherwise the bit jams in the resolidified 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 stone 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 slower to get going.


NT

In article ,
Robin wrote:
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.

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.

--
*If you're not part of the solution, you're part of the precipitate *

Dave Plowman London SW
To e-mail, change noise into sound.

On 22/10/2018 13:27, Dave Plowman (News) wrote:

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.


Standard HSS drill but keep the pressure VERY low.

Bill

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

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"GB" wrote in message
news
On 22/10/2018 11:37, Robin wrote:
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.

[1] http://wiki.diyfaq.org.uk/index.php/...Spur_Wood_Bits


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.

Bill Wright wrote in
news
On 22/10/2018 13:27, Dave Plowman (News) wrote:

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.


Standard HSS drill but keep the pressure VERY low.

Bill


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)

On 22/10/2018 19:08, DerbyBorn wrote:
Bill Wright wrote in
news
On 22/10/2018 13:27, Dave Plowman (News) wrote:

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.


Standard HSS drill but keep the pressure VERY low.



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)



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.


--
Robin
reply-to address is (intended to be) valid

On Monday, October 22, 2018 at 12:37:27 PM UTC+2, Robin wrote:
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.

[1] http://wiki.diyfaq.org.uk/index.php/...Spur_Wood_Bits

--
Robin
reply-to address is (intended to be) valid

I have recently had good results drilling small diameter ( 2 or 3 mm ) pilot 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 allowed the drill to rotate. I got nice spirals of polycarbonate, indicating no 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 counter-sink bit which allowed me to bolt together (with some large washers) the two panes of polycarbonate where the glue had failed (an old manufacturing 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 maintenance of the said caravan).

Sid

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

http://knaustabbert.polyplasticpass....customer/index
http://knaustabbert.polyplasticpass....which-vehicles
http://knaustabbert.polyplasticpass....p-by-step-plan

http://www.polyplastic-pass.nl/english/rapido/index.php

http://lmc.polyplasticpass.nl/EN/customer/index
http://lmc.polyplasticpass.nl/EN/cus...which-vehicles
http://lmc.polyplasticpass.nl/EN/cus...p-by-step-plan

http://sea.polyplasticpass.nl/EN/customer/index
http://sea.polyplasticpass.nl/EN/cus...which-vehicles
http://sea.polyplasticpass.nl/EN/cus...p-by-step-plan

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

On Monday, October 22, 2018 at 9:24:27 PM UTC+2, wrote:
On Monday, October 22, 2018 at 12:37:27 PM UTC+2, Robin wrote:
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.

[1] http://wiki.diyfaq.org.uk/index.php/...Spur_Wood_Bits

--
Robin
reply-to address is (intended to be) valid

I have recently had good results drilling small diameter ( 2 or 3 mm ) pilot 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 allowed the drill to rotate. I got nice spirals of polycarbonate, indicating no 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 counter-sink bit which allowed me to bolt together (with some large washers) the two panes of polycarbonate where the glue had failed (an old manufacturing 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 maintenance of the said caravan).

Sid

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

http://knaustabbert.polyplasticpass....customer/index
http://knaustabbert.polyplasticpass....which-vehicles
http://knaustabbert.polyplasticpass....p-by-step-plan

http://www.polyplastic-pass.nl/english/rapido/index.php

http://lmc.polyplasticpass.nl/EN/customer/index
http://lmc.polyplasticpass.nl/EN/cus...which-vehicles
http://lmc.polyplasticpass.nl/EN/cus...p-by-step-plan

http://sea.polyplasticpass.nl/EN/customer/index
http://sea.polyplasticpass.nl/EN/cus...which-vehicles
http://sea.polyplasticpass.nl/EN/cus...p-by-step-plan

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

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

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

https://www.dft.gov.uk/vosa/apps/rec...Text=Blank&tx=

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

https://www.dft.gov.uk/vosa/apps/rec...efault.asp?tx=

On 22/10/2018 19:29, Robin wrote:
On 22/10/2018 19:08, DerbyBorn wrote:
Bill Wright wrote in
news
On 22/10/2018 13:27, Dave Plowman (News) wrote:

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.


Standard HSS drill but keep the pressure VERY low.



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)



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.Â* The
more so as I'll have no scrap to practice on having ordered cut-to-size.


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

On Mon, 22 Oct 2018 23:16:34 +0100, GB wrote:

On 22/10/2018 19:29, Robin wrote:
On 22/10/2018 19:08, DerbyBorn wrote:
Bill Wright wrote in
news
On 22/10/2018 13:27, Dave Plowman (News) wrote:

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.


Standard HSS drill but keep the pressure VERY low.



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)


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.

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

Just wondering - no material on which to test - if a spade-type tile drill
would do it.
--
Peter.
The gods will stay away
whilst religions hold sway

On Mon, 22 Oct 2018 19:29:20 +0100, Robin wrote:

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.

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


Thomas Prufer

On 23/10/2018 07:41, Thomas Prufer wrote:
On Mon, 22 Oct 2018 19:29:20 +0100, Robin wrote:

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.

Practice on a CD case? Polycarbonate, AFAIK,

No. polystyrene.

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

and thin and grabby, also plentiful
and cheap.


Thomas Prufer



--
"In our post-modern world, climate science is not powerful because it is
true: it is true because it is powerful."

Lucas Bergkamp

On 22/10/2018 12:24, newshound wrote:
On 22/10/2018 11:37, Robin wrote:
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.Â* But what
drill bit should I use?Â* 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.Â* 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.

[1] http://wiki.diyfaq.org.uk/index.php/...Spur_Wood_Bits

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.

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.

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.

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.

--
Regards,
Martin Brown

In message , Robin
writes

Thanks to you and others for all the tips.

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.
--
Graeme

In article ,
Robin wrote:
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.

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

--
*Why is the man who invests all your money called a broker? *

Dave Plowman London SW
To e-mail, change noise into sound.

On Tuesday, October 23, 2018 at 10:56:43 AM UTC+2, Martin Brown wrote:
On 22/10/2018 12:24, newshound wrote:
On 22/10/2018 11:37, Robin wrote:
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.Â* But what
drill bit should I use?Â* 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.Â* 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.

[1] http://wiki.diyfaq.org.uk/index.php/...Spur_Wood_Bits

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.

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.

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.

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.

--
Regards,
Martin Brown

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

Sid

On 23/10/2018 13:29, Dave Plowman (News) wrote:
In article ,
Robin wrote:
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.

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

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.

--
Regards,
Martin Brown

On 23/10/2018 14:52, Martin Brown wrote:
On 23/10/2018 13:29, Dave Plowman (News) wrote:
In article ,
Â*Â*Â* Robin wrote:
I'll pass on grinding bits as (for this ex paper-pusher) drilling
polycarbonate is enough of a learning experience for the present.Â* The
more so as I'll have no scrap to practice on having ordered cut-to-size.

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

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.

On thermoplastics use a hot pointy thing. (calm down pamela)

--
There is something fascinating about science. One gets such wholesale
returns of conjecture out of such a trifling investment of fact.

Mark Twain

In article ,
Martin Brown wrote:
On metal you would centre punch the hole to prevent this skating but
that option isn't available on brittle plastic.

Use a good sharp pointy thing. Like a scriber. To make the location point
for a small drill. Or masking tape.

--
*I feel like I'm diagonally parked in a parallel universe*

Dave Plowman London SW
To e-mail, change noise into sound.

On Tuesday, 23 October 2018 09:56:43 UTC+1, Martin Brown wrote:
On 22/10/2018 12:24, newshound wrote:
On 22/10/2018 11:37, Robin wrote:
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.Â* But what
drill bit should I use?Â* 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.Â* 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.

[1] http://wiki.diyfaq.org.uk/index.php/...Spur_Wood_Bits

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.

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.

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.

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.

Melting is not the problem, it's a good solution.


NT

"Dave Plowman (News)" wrote in
:

In article ,
Martin Brown wrote:
On metal you would centre punch the hole to prevent this skating but
that option isn't available on brittle plastic.

Use a good sharp pointy thing. Like a scriber. To make the location point
for a small drill. Or masking tape.


If using an electric drill - why do so many people wiggle it around as a
final flourish before withdrawing it?

On Tuesday, 23 October 2018 23:10:57 UTC+1, DerbyBorn wrote:
"Dave Plowman (News)" wrote in
:
In article ,
Martin Brown wrote:

On metal you would centre punch the hole to prevent this skating but
that option isn't available on brittle plastic.

Use a good sharp pointy thing. Like a scriber. To make the location point
for a small drill. Or masking tape.


If using an electric drill - why do so many people wiggle it around as a
final flourish before withdrawing it?

to bend the bit of course.


NT