Acrylics and how to tell them apart without the label, cast vs. extruded

insane

New member
I have a bunch of 1/4" acrylic panels out in my garage from a store fixture display. Is there a way to tell if it is cast or extruded?

I plan on using it for practicing with tools and learning to work with acrylics,
I already have my Weld-on 3, 4 & 16 on the way.

Also Is Novus 1, 2, 3 appropriate.
+
NOVUS Buffing Kit
1- Wool Applicator Pad
1- Wool Buffing Pad
1- Backplate Adapter
1-1/4" Spindle Adapter
1- Instruction Sheet

Am I going in the right direction?

Thanks,
insane
 

troylee

In Memoriam
Run a piece through a table saw if it melts its extruded.....cast will cut nice and clean sometimes it chips if it is cheap cast.....but 100% of the time extruded melts and when you have used it enough you can tell by the smell when you cut it....;)
 

Acrylics

Active member
<a href=showthread.php?s=&postid=15426815#post15426815 target=_blank>Originally posted</a> by insane
I have a bunch of 1/4" acrylic panels out in my garage from a store fixture display. Is there a way to tell if it is cast or extruded?
There's a few ways to the trained eye, ear, nose, and throat... but the easiest way is to measure the thickness and the uniformity of it. Extruded will be .236" (6mm) and pretty damned consistent throughout the sheet. Continuous cast materials are very consistent as well but they are pretty rare these days. Cell cast materials will vary from ~.210-.250".

If you look at the surface of the material at a very skewed angle, extruded will have extrusion lines that run in one direction only. Cell cast materials will not have this issue.

Also with most extrudeds, there is a propensity to mottling of the surface with lots of little "pock marks" on it.

<a href=showthread.php?s=&postid=15427214#post15427214 target=_blank>Originally posted</a> by troylee
Run a piece through a table saw if it melts its extruded.....cast will cut nice and clean sometimes it chips if it is cheap cast.....but 100% of the time extruded melts...
HUH??????? What??
If it melts, you're either using the wrong kind of blade or it's dull. Extruded should not melt at all when simply running it through a table saw. I have zero issues with it melting, pretty much ever. If it does start to melt, the blade gets replaced and the problem is solved

Chipping has to do with the saw blade (generally) and even the best acrylics will chip if you're using the wrong blade. The difference in hardness between cast and extruded is only a point or two so a difference in chipping should not be so significant that a layman could easily tell the difference.

And cast will melt too if the blade is dull so not a good indicator

James
 

troylee

In Memoriam
I use the same blades on my panel saw and table saw....amana tool non ferrous triple chip blades 80tooth on the table saw 10" blade and 100tooth on the panel saw 12"blade.....when ever I rip extruded on a table saw especially thick stuff like 3/4" it gums up pretty bad and has a distinct smell.......cast always seems to cut a lot easier and cleaner......same goes for a band saw or jig saw it likes to melt compared to cast.....dunno....its worked for me.......;)
 

insane

New member
<a href=showthread.php?s=&postid=15428058#post15428058 target=_blank>Originally posted</a> by troylee
I use the same blades on my panel saw and table saw....amana tool non ferrous triple chip blades 80tooth on the table saw 10" blade and 100tooth on the panel saw 12"blade.....when ever I rip extruded on a table saw especially thick stuff like 3/4" it gums up pretty bad and has a distinct smell.......cast always seems to cut a lot easier and cleaner......same goes for a band saw or jig saw it likes to melt compared to cast.....dunno....its worked for me.......;)

Do you reverse the blades?
 

Bowman

New member
Absolutley not :eek2: You want to cut your way through not melt your way through. As james said the right blade and the right material feed speed and you should be good. Once your pieces are cut your still gunna have to prep the edges before you can glue it up.
 

Acrylics

Active member
<a href=showthread.php?s=&postid=15428058#post15428058 target=_blank>Originally posted</a> by troylee
I use the same blades on my panel saw and table saw....amana tool non ferrous triple chip blades 80tooth on the table saw 10" blade and 100tooth on the panel saw 12"blade.....when ever I rip extruded on a table saw especially thick stuff like 3/4" it gums up pretty bad and has a distinct smell.......cast always seems to cut a lot easier and cleaner......same goes for a band saw or jig saw it likes to melt compared to cast.....dunno....its worked for me.......;)
Big difference between getting some melting or slag on 3/4" extruded (or stacked sheets) and saying 1/4" melts 100% of the time - which is what the OP is working with.

I'd agree on band saws or jig saws, but IMO they are largely unnecessary for acrylic. I don't even own a band saw anymore and might as well get rid of the jig saw - I can't remember the last time I used mine.

Hell, you can tell brand from brand by smell alone but thats after a while and a few miles of cutting. Not so sure a "newb" (sorry to the OP) could tell the difference between cast and extruded without having done much of it before. What would he compare it too? You have two smells, one is cast, one is extruded, guess...

For thicker stuff or stacking, get a blade with less teeth - will help clear chips better and have less contact with the material. Less contact & better chip clearance = less friction = less heat = less melting

Never ever ever reverse the blade for cutting acrylic....

James
 

troylee

In Memoriam
I guess it was a bold statement saying it all melts.........but honestly I'm with ya james like I mentioned and you just did the smell is the biggest factor for me....as for not owning a bannd saw or jig saw james I make millions of different things out of acrylic building tanks and sumps and such are just for fun...you specialize in them I don't.....but I do use both a jig saw and bandsaw for rough cutting euro braces or making parts for reactors etc...........insane I know I told you to use cast material and this is the best to use......weather or not you have cast or extruded sitting there to play with and learn with is not so much of a big deal.....you just need the hands on practice and either will work....hell if you got extruded and pull off some clean welds cast will be just that much easier for ya.....when gluing. extruded it just breaks down a lot faster with solvents which means you gotta move faster........;)
 
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