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.
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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.
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
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
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.
On Tue, 10 Oct 2017 20:44:39 +0100, Nick Odell
experience into a viable and meaningful comprehension...
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.
On Wed, 11 Oct 2017 05:03:33 -0700 (PDT)
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 15:55:28 +0100, Rob Morley wrote:
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
It's worth using a good file - not worn out - as then another file isn't
needed for a lot of jobs.
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.
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.
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