I’ve got a small rectangular sheet of 3mm thick Acrylic sheet ( about 9″ x 14″) and want to cut a rectangular section out of its centre. I was thinking of drilling holes in the corners and using a jigsaw with a fine blade to cut straight edges along a clamped piece of plywood acting as a straight edge. The cut edge doesn’t have to be super neat as it won’t be visible, but I’m wondering if this method is likely to be successful and what speed I should run the jigsaw at – fast or slow?

Any suggestions from the various handy people who frequent this forum?

Cheers.

I could do with knowing this too. Your method sounds correct but I’d love to hear from someone who’s done it!

Will work perfectly. Nice sharp blade in the saw mind.
Also check the base of the jigsaw for barbs,they can sometimes tear through the covering film(if any) and scratch hell out of the acrylic.

Sounds fine just make sure it’s securely clamped all over, if it vibrates it will crack Where you don’t want it to

That’s the best way to do it, with the sheet supported underneath as much as possible to stop it from juddering. I’d run the saw pretty fast, with a fairly fine blade, as you suggest, again to stop the plastic juddering.

Might be an idea to score the cut lines first – might help control any cracking if it does catch and start bouncing.

Jigsaw, fine blade, SLOW SPEED.

If you use a fast speed it melts the perspex which will ‘glue’ the two halves back together behind the blade. You’ll cut all the way through the sheet and it’ll still be in one piece with a horrible melted messy line in it, which won’t break easily and will leave an awful edge when it does. Cut with a slow speed and you’ll be fine though, nice clean edge. If you see it start to melt, slow the speed down.

I was taught by an old Skool college workshop teacher to put masking tape over the cut firstly to make marking out easily. Secondly apparently the glue lubricates the cut helping it it not melt and stick together and finally it helps prevent the base of the jigsaw marking the Perspex. I can’t say if the lube theory is true but I have always done it this way nice and slowly with a sharp fine tooth metal blade and have never had any problems. I normally run a blow torch over the edge which smooths and rounds the edge.

Andy

+1 for masking tape. Used to use that at school years ago and it kept a perfectly clean cut.

Ideally it would be milled out but using a sharp jigsaw is fine as long as the piece it’s well clamped down and you don’t go too hard and fast! Avoid heating up the acrylic, use a vacuum cleaner or better still a jet or jets of compressed air to clear the swarf from the blade and cool the blade and workpiece. Smooth the cut edges with a file then scrape with a sharp Stanley knife or scalpel to eliminate any stress raisers.

This is a good read for anyone working with acrylic.

I give it to my mate Mark who has a laser cutter.

thanks all, sounds like i’m on the right track. My first port of call is to take it into work to see if I can get them to do it on a band saw or something like that. If they can’t do it for whatever reason I need a backup plan so will have to buy some clamps and a nice new sharp jigsaw blade. I don’t have access to laser cutters unfortunately.

Unfortunately my Jigsaw doesn’t have a variable speed option so might have to invest in a new one!

This has a 3mm acrylic mirror in it.

I cut it with a fine jig saw. Support the back and drill the corners. Take your time!

see if I can get them to do it on a band saw or something

You can’t do it with a bandsaw as the hole is enclosed so as there is no break in the blade you can’t do it.
Jigsaw is perfect, just use a fine blade and support the work.
Check the blade is downward cutting if supporting it underneath.
Tape is good…

Good point on the band saw Kayak!

Drill the corners then hacksaw rather than jigsaw for a little more control? Oreven a dremel with one of those sort of mill profile bits can be quite good at going through some plastics.

Got an off cut to practice on?

Oh and +1 for the masking tape…

If you have access to a router and TCT bits you will get a good result.

a few years ago when iwent to the perspex factory, safety glases had to be worn at all times, reason being perspex splinters react with the eye and can burn into the eye.

top tip, secure perspex sheet to a piece of mdf,with double sided tape under cut line, stops chattering ,leave plastic film on both sides when cutind, also sides will be sharp after cut, unless you used to high a speed, in which case yoll have a melt.

Check your jigsaw, on some you can adjust the forward stroke. Turn this down to the minimum setting.
Carefully when you start and stop the saw. Has a habit of catching on the plastic.