Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

On 10/10/2017 15:19, ss wrote:
Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

Power hacksaw blade, with a temporary handle made from duct tape.

http://www.ebay.co.uk/itm/like/37145...6856138&crdt=0

Stiffer and stronger than a normal hacksaw blade. Fine tooth panel saw
will work, the problem with a tenon saw is that you will have to
maintain a shallow angle to clear the spine.

On 10/10/17 15:35, newshound wrote:
On 10/10/2017 15:19, ss wrote:
Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

Power hacksaw blade, with a temporary handle made from duct tape.

http://www.ebay.co.uk/itm/like/37145...6856138&crdt=0


Stiffer and stronger than a normal hacksaw blade. Fine tooth panel saw
will work, the problem with a tenon saw is that you will have to
maintain a shallow angle to clear the spine.

I don't know if polycarbonate has similar cutting properties to acrylic
but I thought I'd mention that, when cutting Perspex, keeping the cut
cool by moving the saw slowly gives a huge improvement IMO.

Nick

In message ,
newshound writes
On 10/10/2017 15:19, ss wrote:
Twinwall:
What best to use, if possible I dont want to buy as it is a one off
job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

Power hacksaw blade, with a temporary handle made from duct tape.

http://www.ebay.co.uk/itm/like/37145...m=1&adgroupid=
42200108823&rlsatarget=pla-327277252998&abcId=1128946&adtype=pla&merchan
tid=7259694&poi=&googleloc=9045579&device=c&campa ignid=856856138&crdt=0

Stiffer and stronger than a normal hacksaw blade. Fine tooth panel saw
will work, the problem with a tenon saw is that you will have to
maintain a shallow angle to clear the spine.

I have occasionally used a circular saw. Nasty dust so best done
outdoors. I have also used a jigsaw with a fine tooth blade for cutting
PIR foam backed plasterboard.

If you do use a handsaw on thick foam it is worth finding an offcut with
a known 90 deg. corner to use as a saw gauge.

--
Tim Lamb

On 10/10/2017 15:19, ss wrote:
Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

You need some sacrificial boards. Hardboard, ply, whatever. Clamp the
boards on both sides of the sheet. Transfer the cutting line to the top
board. Cut with a fine toothed blade (a steel cutting blade) in a
jigsaw, with the saw set to a slow speed. Slow speed is important. You
are cutting through both boards and the sheet. Ideally you should have
the work on two Workmates (etc) close together with a narrow space in
between them. As an alternative I made a cutting board for this job. It
was a stout piece of 1" multiply with a slot cut in it. After cutting
hand sand the edge.

Bill

On 10/10/2017 20:44, Nick Odell wrote:
On 10/10/17 15:35, newshound wrote:
On 10/10/2017 15:19, ss wrote:
Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

Power hacksaw blade, with a temporary handle made from duct tape.

http://www.ebay.co.uk/itm/like/37145...6856138&crdt=0


Stiffer and stronger than a normal hacksaw blade. Fine tooth panel saw
will work, the problem with a tenon saw is that you will have to
maintain a shallow angle to clear the spine.

I don't know if polycarbonate has similar cutting properties to acrylic
but I thought I'd mention that, when cutting Perspex, keeping the cut
cool by moving the saw slowly gives a huge improvement IMO.

Nick

Very true. You can sometimes get away with a slow (powered) jigsaw. IME
a circular saw is too fast. Not sure about multi tools, may be OK if you
keep the pressure down but cut rate will be slow (although of course
they are unsurpassed for cutting, say, a small rectangular hole in the
middle of a sheet).

I don't have much experience with twinwall. On single polycarbonate and
thin acrylic, deep scoring with a stanley knife and snapping can work,
but I have had cracks divert from the chosen line. If you have a small
protrusion to be removed from the required line, scoring and then
snapping with a pincers or pliers can work well.

You want a sharp saw blade, not a blunt one like the OP says he has.

For trimming down to size, a rasp or surform is best. Angle grinder
(with sanding disk, not grinding one) may work but you need a very light
touch.

In message , Tim Lamb
writes
In message ,
newshound writes
On 10/10/2017 15:19, ss wrote:
Twinwall:
What best to use, if possible I dont want to buy as it is a one off
job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

Power hacksaw blade, with a temporary handle made from duct tape.

http://www.ebay.co.uk/itm/like/37145...m=1&adgroupid=
42200108823&rlsatarget=pla-327277252998&abcId=1128946&adtype=pla&merchan
tid=7259694&poi=&googleloc=9045579&device=c&camp aignid=856856138&crdt=0

Stiffer and stronger than a normal hacksaw blade. Fine tooth panel saw
will work, the problem with a tenon saw is that you will have to
maintain a shallow angle to clear the spine.

I have occasionally used a circular saw. Nasty dust so best done
outdoors. I have also used a jigsaw with a fine tooth blade for cutting
PIR foam backed plasterboard.

If you do use a handsaw on thick foam it is worth finding an offcut
with a known 90 deg. corner to use as a saw gauge.

Oops! I see the OP was about polycarbonate!


--
Tim Lamb

On Tuesday, 10 October 2017 15:19:08 UTC+1, ss wrote:
Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

Stanley knife.


NT

On 10/10/2017 20:57, newshound wrote:

Very true. You can sometimes get away with a slow (powered) jigsaw. IME
a circular saw is too fast. Not sure about multi tools, may be OK if you
keep the pressure down but cut rate will be slow (although of course
they are unsurpassed for cutting, say, a small rectangular hole in the
middle of a sheet).

Yes, but not nice for a long straight cut. If you have to do it use a
steel guide.

For trimming down to size, a rasp or surform is best. Angle grinder
(with sanding disk, not grinding one) may work but you need a very light
touch.

I tried a grinder with a 1mm disk and it overheated the work. It might
be OK if you took it very steady though.

Bill

On 11/10/2017 02:04, wrote:
On Tuesday, 10 October 2017 15:19:08 UTC+1, ss wrote:
Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

Stanley knife.

Assuming this is a 10mm thick sheet, I think you'll be a long time with
your Stanley knife before cutting right through?

On 10/10/2017 15:19, ss wrote:
Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

I know this is polycarbonate, but assuming it's not too different to
Perspex, I used a sliding mitre saw.

I found it cut nicely and didn't melt the material at all. It had a
sharp carbide tipped blade.

On Wednesday, 11 October 2017 03:03:12 UTC+1, Fredxxx wrote:
On 11/10/2017 02:04, tabbypurr wrote:
On Tuesday, 10 October 2017 15:19:08 UTC+1, ss wrote:

Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

Stanley knife.

Assuming this is a 10mm thick sheet, I think you'll be a long time with
your Stanley knife before cutting right through?

He said it's twinwall. Most of the replies have been more suited to solid sheet, and 10mm solid polycarb is not really a diy item.


NT

On Tue, 10 Oct 2017 20:44:39 +0100, Nick Odell
wrote:

I don't know if polycarbonate has similar cutting properties to acrylic
but I thought I'd mention that, when cutting Perspex, keeping the cut
cool by moving the saw slowly gives a huge improvement IMO.

And that can still be improved...

In my experience with acrylic of 8mm or so: Using a large table saw with TCT
blades, going slow still left a raised/melted burr. A faster second pass taking
off a millimeter or less gave a good edge. I think that because very little
material is removed, there is less heat involved.

I have also used compressed air as a "coolant" when sanding edges or drilling.



Thomas Prufer

On 11/10/2017 03:05, Fredxxx wrote:
On 10/10/2017 15:19, ss wrote:
Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

I know this is polycarbonate, but assuming it's not too different to
Perspex, I used a sliding mitre saw.

I found it cut nicely and didn't melt the material at all. It had a
sharp carbide tipped blade.

Thanks all for the replies and ideas, I should have a bit of excess so
can trial different methods and see what works best.

On 10/10/2017 15:19, ss wrote:
Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

My solution to this was to clamp two lengths of floorboard either side
on the twinwall and use the finest toothed manual saw that I had
available moving fairly slowly to avoid melting it and clogging the saw.

Clamped on the keeping side about 1cm away from the line of the cut.

Worked well enough for me on 3m long cuts. It cuts reasonably well once
the thing has been made rigid by clamping it to wooden planks. Otherwise
it flops all over the place making it hard to cut. If it snatches then
there is a risk of fracture so take it easy with the saw pressure.

--
Regards,
Martin Brown

Bill Wright used his keyboard to write :
I tried a grinder with a 1mm disk and it overheated the work. It might be OK
if you took it very steady though.

Just the surface friction from a fast moving disc, without doing any
cutting, will be enough to melt it.

On Tue, 10 Oct 2017 20:44:39 +0100, Nick Odell
coalesced the vapors of human
experience into a viable and meaningful comprehension...

On 10/10/17 15:35, newshound wrote:
On 10/10/2017 15:19, ss wrote:
Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

Power hacksaw blade, with a temporary handle made from duct tape.

http://www.ebay.co.uk/itm/like/37145...6856138&crdt=0


Stiffer and stronger than a normal hacksaw blade. Fine tooth panel saw
will work, the problem with a tenon saw is that you will have to
maintain a shallow angle to clear the spine.

I don't know if polycarbonate has similar cutting properties to acrylic
but I thought I'd mention that, when cutting Perspex, keeping the cut
cool by moving the saw slowly gives a huge improvement IMO.

Nick

I was cutting some perspex last night using a fine toothed jigsaw
blade on slowest setting and the material just welded itself together
at the back of the blade. Fortunately accuracy wasn't essential, but
drilling accuracy was, and a set of Poundland wood drills used at high
speed worked very well.


--

Graham.
%Profound_observation%

On Wednesday, 11 October 2017 11:30:49 UTC+1, Graham. wrote:

I was cutting some perspex last night using a fine toothed jigsaw
blade on slowest setting and the material just welded itself together
at the back of the blade. Fortunately accuracy wasn't essential, but
drilling accuracy was, and a set of Poundland wood drills used at high
speed worked very well.

Drill bits are prone to crack acrylic. I prefer to use a stone in a dremel, it mostly melts the hole. No risk of breakage, just take care to avoid the hole wandering.


NT

On 11/10/2017 11:02, Harry Bloomfield wrote:
Bill Wright used his keyboard to write :
I tried a grinder with a 1mm disk and it overheated the work. It might
be OK if you took it very steady though.

Just the surface friction from a fast moving disc, without doing any
cutting, will be enough to melt it.

The stuff forms a hard bead though which is difficult to get off.

Bill

On Wed, 11 Oct 2017 05:03:33 -0700 (PDT)
wrote:

Drill bits are prone to crack acrylic. I prefer to use a stone in a
dremel, it mostly melts the hole. No risk of breakage, just take care
to avoid the hole wandering.

Using an ordinary drill in reverse rotation might do the trick, or
maybe grind a bit to have negative tip clearance, so the actual
"cutting" is friction but the flute still clears the waste material.
I'm almost inclined to go do an experiment, but there's so much that
actually /needs/ doing that I shouldn't put off any longer.

On Wed, 11 Oct 2017 08:44:02 +0200
Thomas Prufer wrote:

In my experience with acrylic of 8mm or so: Using a large table saw
with TCT blades, going slow still left a raised/melted burr. A faster
second pass taking off a millimeter or less gave a good edge. I think
that because very little material is removed, there is less heat
involved.

Multiple shallow cuts?

On Wed, 11 Oct 2017 15:55:28 +0100, Rob Morley wrote:

On Wed, 11 Oct 2017 05:03:33 -0700 (PDT)
wrote:

Drill bits are prone to crack acrylic. I prefer to use a stone in a
dremel, it mostly melts the hole. No risk of breakage, just take care
to avoid the hole wandering.

Using an ordinary drill in reverse rotation might do the trick, or
maybe grind a bit to have negative tip clearance, so the actual
"cutting" is friction but the flute still clears the waste material.
I'm almost inclined to go do an experiment, but there's so much that
actually /needs/ doing that I shouldn't put off any longer.

It'd need a shallow pit to start without wandering, then a sharp masonary
bit will scrape the material rather than cut it.
At work, we had some backed off bits of about 80 - 85 deg. for material that
would crack with a standard bit.

As an aside, when I wanted a small scraper, I slowly ground a square file
(about 8 - 10mm) with 2 acute angles, 2 obtuse angles and a small chisel
tip. The angles are all sharp and the obtuse ones are ideal for hard
plastics.
It's worth using a good file - not worn out - as then another file isn't
needed for a lot of jobs.
--
Peter.
The gods will stay away
whilst religions hold sway

In message , Bill Wright
writes

The stuff forms a hard bead though which is difficult to get off.

Indeed. I cut quite a lot of the stuff last year, and it takes time,
but my method is Stanley knife first, then pencil in the knife groove
(easier to see), then cut slowly with a hand saw. Fine toothed tenon
saw is good but, as has been said, watch the spine. Finally, a quick up
and down with a surform to remove any bits, and any bead as Bill said.
Easy to form that bead just with a hand saw. My sheet wasn't 10mm
thick, though.
--
Graeme

On 10/10/2017 15:19, ss wrote:
Twinwall:

What best to use, if possible I dont want to buy as it is a one off job.
from a 2 metre sheet I want to cut 3 x2x2 foot squares.
Tools at hand:
Blunt tenon saw, angle grinder, normal saws, circular saw 48 tooth,
Multi tool, stanley knife,jig saw with various blades.

Last time I did that I used a jigsaw with a hacksaw blade in it. Ran at
a slowish speed.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 11/10/2017 04:09, wrote:
On Wednesday, 11 October 2017 03:03:12 UTC+1, Fredxxx wrote:
On 11/10/2017 02:04, tabbypurr wrote:
On Tuesday, 10 October 2017 15:19:08 UTC+1, ss wrote:

Twinwall:

What best to use, if possible I dont want to buy as it is a one
off job. from a 2 metre sheet I want to cut 3 x2x2 foot
squares. Tools at hand: Blunt tenon saw, angle grinder, normal
saws, circular saw 48 tooth, Multi tool, stanley knife,jig saw
with various blades.

Stanley knife.

Assuming this is a 10mm thick sheet, I think you'll be a long time
with your Stanley knife before cutting right through?

He said it's twinwall. Most of the replies have been more suited to
solid sheet, and 10mm solid polycarb is not really a diy item.

I missed that, and the very first line in the OP's post!

On 11/10/2017 08:43, ss wrote:


Thanks all for the replies and ideas, I should have a bit of excess so
can trial different methods and see what works best.

That's *definitely* a very good idea. Good luck with it.