Question about Acrylic

[Brian Book]

Hi All .... just a question about Acrylic .... what is everyone's preference .... I know that one cuts better than the other ....and the engraves better ... would Cast Acrylic be better for most projects .... or would one just get the different thickness of both types ?

I'm heading out tomorrow to get my stock before the machine arrives ... I was thinking 2mm , 3mm , and 6mm for most projects .... is this right

Thanx for any and all replies :)

Brian

[David Somers]

Hey Brian!

Definately Cast for most purposes involving a laser. Not sure what your acrylic shop carries. But if they have PetG film or Polycarbonate Film you might play with that as well. And perhaps some mylar film. (not mirrored to start) I use the filmes to make stencils for folks for painting when asked. I also use a slightly thicker Polycarb film (.2 I think) to make guides for newer Urban Sketchers to help them with perspective and proportions when they are out sketching. Thin enough to fit into their watercolor journals but thick enough to be durable. It also cuts nicely once you get the speed and power right for your machine. Don't forget some acrylic adhesive so you can assemble more complex pieces if you want.

[Keith Downing]

Hi All .... just a question about Acrylic .... what is everyone's preference .... I know that one cuts better than the other ....and the engraves better ... would Cast Acrylic be better for most projects .... or would one just get the different thickness of both types ?

I'm heading out tomorrow to get my stock before the machine arrives ... I was thinking 2mm , 3mm , and 6mm for most projects .... is this right

Thanx for any and all replies :)

Brian


For cutting extruded is slightly better IMHO, for engraving cast is the way to go. I'm not sure about buying a bunch of stock in advance though.

The only way I would do that would be if I had an opportunity to buy in bulk at a huge discount. This stuff gets expensive, especially the cast (in my area anyways), it's heavier than you think it will be when dealing with multiple pieces, and you need somewhere to store it safely where it won't get nicked, scratched, etc. You also don't know exactly what you might end up wanting (size, thickness, color). Personally I ended up doing several projects with white and the mirror. Still have a couple sheets of thin clear stacked under some plywood in my shop from 6+ years ago.

If you have a large plastics supplier nearby, you might drop in, introduce yourself and ask if they have some drop or scrap pieces they'd let you have for cheap or possibly free to test your new machine on. Half the time the busy shops have no use for small pieces and will be happy to have you haul it off.

[David Somers]

Good thoughts Keith! Here in Seattle Tap Plastics has a nice stock of cutoffs they sell cheaply and make great pieces for playing with and for small projects. I keep a piece or two of larger stock in the shop in case someone asks for something. Saves me a trip to town, but I also dont like to keep large volumes of anything in my garage. Not that much room!

[Ross Moshinsky]

Extruded cuts the best but is far more brittle. Cast cuts well and engraves with a strong frosted finish. Unless you have a specific need for extruded acrylic, I'd recommend stocking just cast. That way you're covered for any project.

You might want to go out and get some 1/8" wood (MDF or BB) to start with as well. It's a heck of a lot cheaper than acrylic so it's probably a better material to cut your teeth on.

[Joe Pelonio]

It depnds on the application. I normally use cast, but for templates that are used for some other process (such as quilting, or machining) I'll use extruded. It's more durable, and cheaper for large quantities.

[John Lifer]

One thing to note, if you store paper protected acrylic, do not let it get hot. David doesn't need to worry about it, but I ended up tossing several sheets of 1/4" that I had let go thru a couple of years in my hot shop in Mississippi. Couldn't get the paper off at all. Don't know about film covers, but I'd not get to much if you store where it gets hot.

Oh, Brian, Ross is right. I went out to my big orange store and picked up a couple of sheets of cheep ply 2.7 and 5mm thickness. Cost me less than $20 and I cut into roughly 2ft x4ft pieces that will fit in my laser... And I've had fun making a lot of stuff for cheap. Found some cast in various small pieces on eBay, nothing close around here that I've found, but that cast stuff is expensive!

[Brian Book]

well just an update .... I went to the plastic supplier .... they also produce displays and do signage ... they basically stock Extruded Acrylic because it bends so much more easily .... they can order me in Cast Acrylic ... so I may have to order full sheets or look for another supplier near by .... not sure there is :(

And Baltic Birch in my area is pretty well non-existent :(

Thanx for the input :)

Brian

[Tony Lenkic]

Brian,

Where are you located? Someone may have a suggestion if we know your location.

[Bill George]

amazon dot com, look for cast acrylic, it comes in pre cut sizes. I have a lot of 12x12 inch on hand. Way cheaper than having someone else order just for you. If you have Prime its free 2 day shipping in a lot of cases.

[Brian Book]

Tony Burlington, Ontario .... I know there is Plastic World in Toronto .... but that is a ways away.

Brian

[Tony Lenkic]

Brian,

Trotec Canada has cast acrylic in various colours. I usually pick up extruded off-cuts at Sabic polymers (hwy 7 & Airport road).
There are number of other distributors mainly for sign industries in GTA.

[Keith Outten]

When I need extruded acrylic I visit my local picture frame shops and purchase their drops. I can usually get about a hundred pounds of drops for ten bucks. Cast acrylic I purchase from a local supplier but I have to buy full sheets.
.

[John Blazy]

Good idea on getting drops from Pic frame shops Keith.

I do about 99% cutting only on my laser, both cast and extruded, mostly extruded cus I can get it in film mask, which is awesome for the laser, and peels easily.

Here are several important things I learned:


Do not glue (solvent cement or reactive 2K acrylic solvent cement) immediately after lasering - let it sit for a week or two or else major crazing cracks form, and even then cracks are likely. I anneal parts to be glued in a small oven - 2 hrs @ 180F then slow cool down. Eliminates 90% chance of cracks.
If you don't want to anneal, then laser oversize, then machine off at least 3/32" of lasered edge
Don't always get in the habit of cutting at the highest speed that barely cuts through for efficiency. Lots of wasted time spent weeding a panel then trying to razor through only a few spots that may warped out of focus or whatever reason. Run a tad slower, and you eliminate non-cuts, and going even slower leaves an insanely smooth polished edge - too fast and you get the coin edge.
Old paper masking is my biggest PITA. Some just won't come off from cuttoffs I have kept for too many years. But pour mineral spirits all over it, wait a little while, and it peels right off easily.
lastly, do not get alcohol anywhere near a laser cut edge. I am even afraid of breathing on those edges if I have been drinking. I accidentally oversprayed some veneer softener (alcohol in it) just slightly onto a stack of fresh cut acrylic, and tons of nasty cracks everywhere. Alcohol is great to remove goo off the face of acrylic though.


You can make a beveling jig to cut miters or make decorative polished beveled edges. Can't believe so few know this trick.
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[John Lifer]

Brian, this is label from my thinner sheet of plywood from big orange. It is a decent ply, no voids but the 5mm has some thicker glued areas that tend not to cut consistently.
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[Brian Book]

Hello All .... and Thanx for the replies

Tone I'll have to get a Trotec Catalog with prices and compare

Keith .... Good Ideas .... will have to try and see where I have a Picture Framing place :)

John Blazy .... very good tips .... thanx for the heads up :)

John Lifer .... seems the Big Orange in Canada doesn't carry the same products as the U.S.A. ??? :(

Brian

[Tony Lenkic]

Brian,

I have few contacts for you to check out.

Plastics
Plastic & Paper Sales Inc
Laird Plastics, Inc
Johnston industrial plastics
Plas-Tech Inc
EM Plastic & Electric Products Ltd.
Piedmont Plastics
WJT Distributing Inc


Plywood
www.forloversofwood.com
www.exotic-woods.com/subcategory ... birch-play
www.aircraftspruce.ca/catalog/wppages/finnishbirch.php

[John Lifer]

Nah, Canadians just don't want their hardwoods back from the Chinese :-).

[Brian Book]

Tony .... Thank You for the links .... will definitely check them out ... but as far as Exotic Woods go .... they are just down the road from me .... when I stopped in to see what they had .... Huge disappointment .... it surely was not Russian Baltic Birch .... absolutely terrible :( .... I walked back out !

John you could be right :)

Brian

[David Somers]

Brian, I believe Rockler has a shop in Ontario, CA. They carry decent ply's. Though at least here in Seattle I dont buy wood from them since they tend to be more expensive than other sources available in town. They are a potential source for you though.

I know Thomes Canada (a supplier) carries down to 1/4" BB ply. I dont know who they supply too. You might call them and ask.

I also see Workshop Supply in Ontario (East Embro) carries down to 1/8" BB in a B grade.

Hopefully those 3 get you a local source!

Dave

[Jed Lawrie]

Vote for extruded here

[Bert Kemp]

Why do you prefer extruded?


Vote for extruded here

[Brian Book]

Hi all .... again thanx for the replies .... the reason I would like to get Cast Acrylic is because I'm told when you engrave it it finishes a snowy white and really good for Edge Lit Signs .... Extruded engraves clear and doesn't show up as well.

My understanding is Extruded cuts better than Cast ?

May I ask what people use the Cast or Extruded for ?


Brian

[Clark Pace]

Lets clarify. Extruded laser cuts better than cast or flame polishes better. But cast cuts better on a saw or routing based system. Of course engraving to a nice off white white works best on cast. So it depends on what you want to do.

[Bert Kemp]

I use cell cast for
Edge lit designs


Hi all .... again thanx for the replies .... the reason I would like to get Cast Acrylic is because I'm told when you engrave it it finishes a snowy white and really good for Edge Lit Signs .... Extruded engraves clear and doesn't show up as well.

My understanding is Extruded cuts better than Cast ?

May I ask what people use the Cast or Extruded for ?


Brian

[Brian Book]

Hi Bert ... I've not heard of Cell Cast .... I'm going to have to do some research ! :)

Brian

[Bert Kemp]

I think its just a name they use .

[Jed Lawrie]

Why do you prefer extruded?

I rarely engrave. Mostly cutting. Extruded seems to cut easier

[Bert Kemp]

Ah Ha got ya


I rarely engrave. Mostly cutting. Extruded seems to cut easier

[Ted Marshall]

One issue I've seen with extruded 1/8", at least from my supplier, is warpage. Some 9" long cut pieces showed about a 1/4" warp, ends compared to middle. 1/8" cast similarly cut showed no visible warp. Obviously, if you're mounting the finished piece, this probably isn't a problem but if the piece is simply to be laid on another surface, this can be an issue. I also expect that thicker pieces won't have the same problem.