cutting perspex

[caretaker]

I have a sheet of Perspex, 4ft x 2ft and won't to cut it to 1 x 4 but what tool to use.
I have a band saw table model. May not use this.
I have a jig saw 240v hand held. May use this.
I have a circular hand saw. A bit to powerful.
The jig saw is my first choice, i will clamp it to my bench with a 5ft long peace of wood and get my wife to hold the over hang as i cut/saw it.
Or use a hand saw but the bench may be to high.

 

[wizard]

i use something like this

tile saw

 

[Lons]

I always use a table saw with min 48 tooth blade (but you don't saw what thickness acrylic so I assume will be either 3mm or 6mm.)

Jigsaw is possible again with fine blade but unless your jigsaw has variable or a slow speed, I wouldn't recommend it as the heat build up caused by friction will melt the acrylic. Essential to wear eye protection btw as hot acrylic chips can do some very serious eye damage. :shock:

Without a tablesaw, I personally would clamp and cut by hand with a crosscut or tenon saw.

If no more than 3mm thick, it's easily snapped instead of cut. Score a line deeply on both sides, clamp to the edge of the bench with timber on top then clamp timber to both side at the other side of the scored line and bend to snap. It won't work without being clamped and supported!


I have a background in semi-finished plastics btw

Bob

 

[Paul Chapman]

I would fix it securely to a piece of sacrificial MDF and cut it with a router. That's how I made this dovetail marker from perspex



You can also plane the edges with a finely set block plane.

Cheers :wink:

Paul

 

[jaywhoopee]

I used my band saw on its slow speed with a fine blade when I made my circle cutting router base.


John

 

[Spindle]

Hi

You can 'cut' Perspex in a similar manner to glass.

I score it using a broken hacksaw blade ground to a slight hook shape, clamp it so as the score runs along the edge of a bench / table etc. and the clamping batten, (score uppermost),and then bend the overhang down. If the Perspex is thin it will help to sandwich the overhang between two boards for support when bending.

Regards Mick

 

[DTTech]

We score and snap 3mm. I dont worry too much about the clamping, as long as its held firmly along a nice smooth square edge it snaps easily enough. I do it this way several times a day. As long as your score is deep enough and deep enough right to the ends it will snap square. I use a stanley hook blade in the knife holder

We also use the Bandsaw but I prefer the snap method as acrylic really takes the edge of a bandsaw blade quite quickly (especially pigmented stuff).

 

[Lons]

We score and snap 3mm. I dont worry too much about the clamping, as long as its held firmly along a nice smooth square edge it snaps easily enough. I do it this way several times a day. As long as your score is deep enough and deep enough right to the ends it will snap square. I use a stanley hook blade in the knife holder

I use the hook blade as well but as suggested a ground hacksaw blade will work.

I agree with your method of scoring just one side and do it that way myself but there are risks. Cast acrylic is brittle and the inexperienced tend to be overcautious when scoring and snapping.
Scoring by its nature creates stress in the acrylic surface and the score always has micro cracks. If the cut isn't deep enough or more commonly the snapping action is too cautious then the micro cracks can spread when snapping and the acrylic can be ruined - I've seen it happen more than once which is why I always recommend scoring both sides and clamping / supporting both sides of the cut which always results in a clean snap.

dead easy when you've done it a couple of times though........but then isn't everything!

Bob

 

[Tony Spear]

When I did some workshop windows I did it with a jigsaw using blades from here:

http://www.uk-jigsawblades.co.uk/conten ... lades.html

 

[srp]

There are different types of acrylic. The best for machining is cast acrylic. Extruded acrylic is horrible to machine - very prone to overheating and consequent binding of the cutter.
Slow cutter speeds and anything other than very light feed speeds leads to chipping and cracking on the edges of the cut. Fast cutter speeds and light feed pressure give a much better finish. If the blade is specifically designed for plastic it will give a much better finish as well (talk to someone like Doug at Cutting Solutions). The dovetail template pictured above is an example of a good quality cut - router cutter speeds are high compared to things like jigsaws.

 

[Lons]

There are different types of acrylic. The best for machining is cast acrylic. Extruded acrylic is horrible to machine - very prone to overheating and consequent binding of the cutter.
Slow cutter speeds and anything other than very light feed speeds leads to chipping and cracking on the edges of the cut. Fast cutter speeds and light feed pressure give a much better finish. If the blade is specifically designed for plastic it will give a much better finish as well (talk to someone like Doug at Cutting Solutions). The dovetail template pictured above is an example of a good quality cut - router cutter speeds are high compared to things like jigsaws.

+1

Extruded is easily recognised especially in the clear version as when you look along the surface the extrusion lines can be clearly seen. Cast acrylic has an excellent surface and is virtually glass clear (it's cast in sheets between glass plates wherease extruded is pressed through rollers and chopped to length).
it's a long time since I was in the plastics industry but there was little call then for extruded except for leaflet display stands and supply otorooflight manufacturing and even that was limited as PVC and Polycarbonate were much more suitable.

Bob

 

[Eric The Viking]

I made an silly person of myself -- not all that unusual -- I tried to cut down my motorbike's windscreen (touring Beemer - the screen was more like a sail really).

I used a jigsaw, with too fine a blade. It all got quite hot, and the cut healed up again behind the blade. Daft really. A tenon saw, or your bandsaw (with dust extraction) will work fine. You can clean up afterwards with successive grades of wet+dry and polish with Brasso to a mirror edge. The key seems to be the feed speed, as others have said, and really sharp teeth, so it always cuts and doesn't rub (generating heat). A good set to the blade helps (wide apart teeth left and right, narrow 'body' to the blade in comparison), because it helps stop friction heating, and will let you turn the cut if you need to.

You can 'wipe' a blowlamp over the edge after cutting to smooth it off. The professionals do this, but I've only ever cocked it up in the past. You need a hot-ish flame, passed over only once, at just the right speed (quite fast). You're aiming to melt just the very edge, not heat the material itself). If you can weld lead for plumbing and roofing, you'll probably do just fine -- I can't, though I've certainly tried!

E.

 

[misterfish]

I recently had to cut a sheet of 3mm perspex and after searching took the plunge and cut it on the table saw. I used the blade from my radial arm saw - 60 tooth negative rake and it cut perfectly.

The info I found warned that using a bandsaw or jigsaw would be likely to melt the edges which would stick together after being cut.

My concern was that the plastic would shatter when it came into contact with the table saw blade but it cut with no problem and no chipping.

Misterfish

 

[Lons]

I recently had to cut a sheet of 3mm perspex and after searching took the plunge and cut it on the table saw. I used the blade from my radial arm saw - 60 tooth negative rake and it cut perfectly.

The info I found warned that using a bandsaw or jigsaw would be likely to melt the edges which would stick together after being cut.

My concern was that the plastic would shatter when it came into contact with the table saw blade but it cut with no problem and no chipping.

Misterfish

And that's the secret of success - the right blade and the confidence to push it through at the right speed.

We were semi-finished plastics distributors (ICI Perspex being our acrylic product) and supplied to all industries. We cut a lot of sheet plastic into various sizes, some quite small using wall saw and a Wadkin table saw. Blades were always negative rake 48 or 60 tooth and were sharpened every couple of weeks maximum.
Zero clearance blade insert and any sheet plastic from 2mm up was not a problem. We did cut a lot of 1.5mm polycarb for police visors which needed sacrificial hardboard support as it was too expensive to risk without and the table saw would cut just about anything we asked of it though sometimes with different blades as we also supplied aluminium / plastic composites
As branch manager, it wasn't my job to cut but circumstance dictated that I rolled up my sleeves when necessary and being a woodworker, I quite enjoyed being away from the phones.

Eric

Flame polishiong edges is dead easy, just needs a little practice but it might be you had an unsuitable material. It's really only effective with cast acrylic as the extruded products don't flame polish well and poly and pvc are hopeless. The secret is to first prepare a nice smooth edge, if you don't the result will look like the surface of a file! The just move the flame at a constant speed as you can watch the edge form. - Not much good if you suffer from "the shakes" of course :lol: I never came across a pro who didn't use flame methods due to time savings.

Great fun line bending and polishing to form photo frames but if you get carried away, it gets to the stage where you can't give them away.

Bob