My (enormously intelligent yet commonsense-bereft) wife ordered some perspex sheet to go inside a clip-frame for a poster

She didn’t measure the old cracked piece, she measured the outside of the frame and you’ll never guess ….

So, how would you reliably trim 5mm off the edge of a biggish sheet of 2mm perspex?

(Sawing sounds like a shit idea to me. Stanley & snappage sounds dodgy too. I thought I could maybe try sanding or run a woodworking plane over it)

Router?

I’ve used a jigsaw on Polycarbonate sheet and it just melted the stuff, made a right mess as it self-welded behind the blade from the heat of the friction.

Angle grinder with a cutting disc and a straight edge, do it in a few light passes and it won’t melt back on itself.

Ordinarily I’d say Stanley / snap, but taking 5mm off is going to be tricky I’d have thought.

Did she order it online? Might be better all round just to kick it back and reorder.

Scribe it with a Stanley knife and a straight edge. If its only 2mm itll be fine. A slightly blunt Stanley blade is actually better.
Trust me, I’m a picture framer.

Did she order it online? Might be better all round just to kick it back and reorder.

CBA sending it back but may end up reordering if the cut goes tits-up

(we’ve actually ordered twice so far anyway – the 1st was 10 times too small as she ordered in cm, not mm 😆 )

That would be ten times too big, no?

Take it to a sign writers (most signs are Perspex now so they are set up for cutting)

she ordered 40×60 instead of 400×600

Yeah, could take it somewhere – my daughter’s school apparently has a LAZORcutter but they’re not doing that without me firing it !

Aha, I see what you mean.

@skink – any top tips for a clean cut ?

(I’m thinking of using masking tape and a nice long steel ruler)

I was hoping you were going ahead with your conservatory. 🙂

DD, my plan now is to glue together all the offcuts and ruined bits from the many, many inevitable reorders of this frigging thing and make a massive dome to cover the entire house 🙁

Masking tape, clamp it to a bench, mark up with a straight edge and a scriber or stanley.
I have used a tenon saw before now, just be patient and gentle. With just 5mm to take off thats going to be tricky.
Can use a plane, use a small block plane, the blade is usually the other way up to a regular sized plane, it cuts very well, again just be patient! Lots of gentle strokes not taking too much off at a time.

It will crack the moment you think ah, I’ve got this sorted!

Jigsaw with a very fine blade will work fine. I use a circular saw with 96 teeth or a bandsaw at work and cuts fine. The schools use the circular saw for cutting up acrylic sheets for the pupil’s projects.
Masking tape works well for marking your line, just take it easy and let the blade cut so light pressure.

You need a laser cutter. If you’re in East Lancs / Nth Yorks and it’s smaller than 600 x 300 I could help as I happen to have one.

Just seen you’re down south – lots of schools have laser cutters now – ring round a few – never know you’re luck. It will cut with a clean polished edge and absolutely straight.

Alternatively for less than a tenner plus postage order one the right size

bandsaw, local joinery shop, dont remove the plastic ilm or it will scratch.

Use the laser.

Just had this job done by Fablab in Exeter library, excellent results. Find one

or a Water jet cutter. Probably one on an industrial estate near you.

Laser if you can get access/know someone who can do the CAD work, setup, etc. and work precisely to take the right amount off. It leaves a great edge finish on acrylic.

If you have one: A router.

If not, probably cheaper to order a new piece that’s the right size…

scaredypants – Member

DD, my plan now is to glue together all the offcuts and ruined bits from the many, many inevitable reorders of this frigging thing and make a massive dome to cover the entire house

“We’ve got 50 tons of plastic, we’re gonna laminate your house”

Really can’t condone this, but if you like it risky…

Heat a piece of metal (old coat hanger?) and use it to trim the excess Perspex.

Gloves
Eye protection
Fire extinguisher
Well ventilated workspace
Etc, etc.

Heat a piece of metal (old coat hanger?) and use it to trim the excess Perspex.

I’m not a perspexist, but THAT sounds like a great idea. Pics/video please. 😀

Loving some of the elaborate solutions here for taking 5mm off a sheet of acrylic.
If you can’t find a CAD designer,a laser cutter and a large hadron collider, just find someone who’d have a table saw and a piece of sandpaper wrapped around a block. 😉

So then,

I make a DIY forge using a petrol-powered leaf blower and a chi chi kettle barbie and use that to heat a jagged piece of metal magnesium before using that to cut the perspex

Should I be doing this freehand rather than clamped, and naked ?

I’d follow rout it off with a laminate trimmer. Sharp bit and move the router quickly for a nice finish. The risk is chipping the corner but masking tape should help.

Masking tape and

You might think its a shit idea OP but guess what, it works.
Turn the blade 90 degrees, lay the sheet on the edge of you workbench and cut slowly. Sandpaper the just to take any burrs away.
Or buy a bloody expensive electrical whatever, use it once and keep it on the shelf as your mancave will look more impressive.
Or just order another piece the right size.

Scribe it with a Stanley knife and a straight edge. If its only 2mm itll be fine. A slightly blunt Stanley blade is actually better.

^^ this

score it several times both sides and snap the excess off with pliers

Try this and let us know how you get on 😉

If you make a mess of it just declare the results to be “Artisan” and you’ll be sorted.

Seriously though – Stanley and straightedge. I assume that you’re not taking 5mm off each of the 4 sides rather than 10mm off 2 sides.

Chainsaw…..you know you want to…..

Surely Semtex is the correct answer…

I hope you’re gonna flame polish the edge, once you’ve cut it?

I read on a forum recently about some guy cutting plastic sheet using a circular saw blade only he’d flipped it around and use the sloped side of the teeth. Reckoned it gave a nice finish and if used slow enough didn’t allow the stuff to re-join, though I reckon getting some water in the mix would aid any heat issues.

See that pizza cutter up there – heat it and bob’s your uncles mates dead pig’s severed head.

Just don’t do what Edd did on the Wheeler Dealers I watched last night and try to cut it with an air-saw… cue a massive crack in an £800 piece of moulded acrylic. Poor bloke genuinely looked like he was going to cry! He got another one and ended up basically sanding it down to size (which took him 6 hours 😯 )

Take it to a sign writers (most signs are Perspex now so they are set up for cutting)

Nope. If they specialise in acrylic they’ll have a laser cutter or CNC router which will do the job but otherwise they’ll just buy the acrylic in pre-cut/drilled as needed as the material is such an arse to work with. Unless you’re thinking of a very specific industry most signs are definitely not made from acrylic; there are plenty of cheaper & better alternatives.

Acrylic (Perspex) is not the right material for the OP’s application anyhow. You would’ve been better off with 2mm clear solid polyester sheet. You can just score that with a stanley and snap it cleanly in 2 seconds, no chance of cracking it.

Nope. If they specialise in acrylic they’ll have a laser cutter or CNC router which will do the job but otherwise they’ll just buy the acrylic in pre-cut/drilled as needed as the material is such an arse to work with. Unless you’re thinking of a very specific industry most signs are definitely not made from acrylic; there are plenty of cheaper & better alternatives.

i get all my acrylic/perspex* cut at a local signwriters, had circular as well as odd shapes and holes cut in sheets. i use it for photographic backgrounds, their main trade is in those big shopfront signs for take-aways.

*i have no idea of the exact material they use and if it is Perspex© or some other acrylic type substance.
** no idea what they cut it with, its nice and clean whatever it is.

Just making the point that if OP were to pitch up at most local sign writers asking to get a piece of acrylic cut, he’ll probably just get handed a hacksaw 🙂 (speaking as a sign writer, who knows lots of other sign writers).

I just hope we get to find out what the OP did and if it worked.

(I am not a signwriter)