Anyone got a suggestions for cutting 6-8mm thick perspex

[SeeO2]

Although not as accurate a multi tool is good for cutting most plastics due to the finer blades , speed control makes it even better imho

Maybe not for 200 pieces though.

 

[TimV]

All the above, plus: (1) in my experience it tends to become more brittle (and prone to cracking) with age, so be particularly careful as this is second-hand. (mind you, the stuff I discovered this on was much older than yours will be). (2) I have successfully profiled it on a milling machine but am not sure whether a router is OK as the cutting speed is faster - I would defer to others on this point, but suspect it's worth a try as long as you watch out for the heat (3) if you have rough edges then very judicious application of a heat gun will remove the sharpness, and make the edge clearer again, but don't overdo it as it will soften- perspex can be heat-formed very nicely. (4) in case you didn't know, you can stick pieces together with acetone.

 

[throbscottle]

The bits of acrylic I've cut have been with a hand saw and it worked very well. Cuts easily enough. I'd go for a hard point panel saw. My power tools are too cheap and basic to chance using for it - I'd probably just get partly melted shards!

 

[ajs]

Whenever I need to do this I use a scroll saw. 90% of the time that's with a 14tpi coping saw blade, moderate speed and the sheet pushed through at it's "natural" rate - that is, the speed where increasing the force applied does not materially increase the cutting speed. I find you don't need to worry unduly about melting, it hacks through the sheet quick enough to be a non issue.

The coping saw blade leaves a nice uniform ridged finish not unlike a milled effect. If that's not what I want I switch to a relatively coarse piercing saw blade which gives a silky smooth finish that needs the bare minimum of polishing to make crystal clear.

Using only hand tools my first stop would be a hacksaw if you can work around the frame. My concern with a panel saw is they're a lot coarser and potentially prone to chipping, although modern Perspex is slightly flexible and a lot tougher than it used to be.

 

[throbscottle]

Hacksaw is too cloggy. Needs courser teeth. 14tpi does it.

 

[johnb80]

There are two varieties of acrylic, cast and extruded. Cast Acrylic is more forgiving and less prone to cracking, extruded acrylic is more accurate but has a lot of inbuilt stresses.

The best way to cut Acrylic is with a laser cutter which doesn't have to cost a fortune and would be worthwhile for a large number of cuts. If you fancy taking a trip to Gainsborough, you can use mine.

 

[meccarroll]

I have a CNC with spindle and the rescommended bit on a CNC for perspex etc is a single flute up cut bit.

"Single flute" so the waste material clears quickly and does not rub against the perspex causing met.

"Up cut" again pulls the waste material out and away quickly helping keep the cut cooler and prolongs the life of the bit.

When you cut down the waste material is pushed down into the cut and can cause heat build up before it is cleared. Not too much of a problem with some materials but perspex needs extra care in this area.

I am not suggesting you buy a CNC to do the job but instead just thought the info might be interesting if you try using a router. You can make a sled for a router in which case the base of the router would not have to travel over the perspex and potentially scratch it. Also most routers have speed control which would be useful.

 

[meccarroll]

There are two varieties of acrylic, cast and extruded. Cast Acrylic is more forgiving and less prone to cracking, extruded acrylic is more accurate but has a lot of inbuilt stresses.

The best way to cut Acrylic is with a laser cutter which doesn't have to cost a fortune and would be worthwhile for a large number of cuts. If you fancy taking a trip to Gainsborough, you can use mine.

That is a generous offer!

 

[Inspector]

You could buy a plastic cutting blade for your table saw or perhaps a track saw. https://bandsawblades.co.uk/product-category/circular-saw-blades/plastic-circular-saw-blades/ They are a triple chip type so maybe a blade for sheet goods would be similar.

A long time ago I cut some up on the table saw for a boat and there was no problems. I can't remember what blade I used but I hand sanded the edges with a sanding block and then went over them with a cabinet scraper. Got the edges very smooth and clean. Now I would probably flame polish them.

Pete

 

[artie]

I had occasion to cut some 5mm perspex like stuff today.

And since I was using off cuts of which I have many I could afford to experiment.

Just used my general purpose wood blade which is far from new and the standard throat plate.

The cut was perfect, better than the photography.

The saw, not that it matters is a Metabo 254m

 

[Sideways]

You might well find that after a couple of dozen cuts, the blade has heated substantially and the cut quality goes to the dogs. Just a caution....

 

[johnb80]

You may also find stress cracks appear over time along the cut edge, cast acrylic less susceptible than extruded acrylic.

 

[Lons]

There are two varieties of acrylic, cast and extruded. Cast Acrylic is more forgiving and less prone to cracking, extruded acrylic is more accurate but has a lot of inbuilt stresses.

I respectfully suggest that you have that the wrong way around.

Cast and extruded are very different materials, cast being produced in small batches / sizes with a far better surface finish and clarity as well as better chemical resistance. It is also manufactured to tighter thickness tolerances than extruded, that being my point.

Extruded is exactly as described, faster production on continuous rolls then chopped off to length. You can see the ripple effect extrusion marks if you look closely. It is generally cheaper and most suitable for thermoforming as easier to work than cast. Both materials will crack and craze if best practice isn't followed when cutting, drilling and machining.

It's a long time since I was stocking ICI Perspex as a distributor branch of a national company but production methods haven't changed since I saw them in action a number of times at the factories.

 

[MikeJhn]

All cut with the blade shown, without any problems.

 

[johnb80]

I respectfully suggest that you have that the wrong way around.

No problem, I only speak from experience of laser cutting and routing Acrylic.

Cast and extruded are very different materials, cast being produced in small batches / sizes with a far better surface finish and clarity as well as better chemical resistance. It is also manufactured to tighter thickness tolerances than extruded, that being my point.

I was told and it seemed to be true that extruded was more accurate due to the way it's manufactured, the acrylic being forced through a dye. Cast Acrylic not being formed through a dye isnt as consistent. The tolerances on thickness were always better on extruded when I checked.

Extruded is exactly as described, faster production on continuous rolls then chopped off to length. You can see the ripple effect extrusion marks if you look closely. It is generally cheaper and most suitable for thermoforming as easier to work than cast. Both materials will crack and craze if best practice isn't followed when cutting, drilling and machining.

Yes they do BUT extruded is dreadful for routing, you end up with Acrylic toffee on the cutter and cuts aren't clean. Cast machines way better with much cleaner cuts and finishes. Laser cutting is fine on either but the extruded can often show stress crack after a couple of days, cast has no such issues.

It's a long time since I was stocking ICI Perspex as a distributor branch of a national company but production methods haven't changed since I saw them in action a number of times at the factories.

Aye, I too have seen Acrylic in the making and made in excess of 22,000 of these over the last 15 years which is where I learned most of what I know about working with Acrylic.

Thanks for correcting my errors

J

 

[Lons]

Is that a dispenser of some sort John and what's in it?

My personal experience of routing is the same as yours, extruded can melt very quickly with a router if you aren't careful but it bends much easier using a simple line bender. Also flame polishing the edges is far better using cast.

I left the industry more than 30 years ago and still have a stock of offcuts I'm slowly using up. I'll be sorry when it's all gone and I'm forced to buy it.

 

[johnb80]

Is that a dispenser of some sort John and what's in it?

Its a track ballaster for model railways and lays the scale small stones (grit) in between the rails and at either side of the rails. They were mainly laser cut but the grooves that sat on the rails in the base were critical for correct operation in terms of width, depth and shape, these were routed.

My personal experience of routing is the same as yours, extruded can melt very quickly with a router if you aren't careful but it bends much easier using a simple line bender. Also flame polishing the edges is far better using cast.

I absolutely hated extruded acrylic, i received some in an order for the ballasters and was horrific with stress cracks all over the place after a few days. The whole batch of ballast spreaders had to be scrapped, i had cut a complete 1220 x 2440 sheet on the laser taking 2 days, it all ended up in the bin, never again.

I left the industry more than 30 years ago and still have a stock of offcuts I'm slowly using up. I'll be sorry when it's all gone and I'm forced to buy it.

When I first got my laser cutter I bought 1.2 tonnes of 4 mm medite (laser compatible mdf) it was a great material for prototyping items and it took years to use up my supplies, like you say, it was a sad day when I had to buy more. These used up my last supplies rapidly

 

[Lons]

Interesting projects John. Thanks for sharing.
My laser is just a hobby Creality Falcon2 (20w) and little used at the minute especially since I got a 3D printer but that's reminded me to get some Christmas ornaments cut for my granddaughter to paint.