[kvom]

I want to machine some 1/8" thick clear acrylic. Gwizard can give feeds and speeds, but any other advice would be appreciated.

[FineLineAuto]

I want to machine some 1/8" thick clear acrylic. Gwizard can give feeds and speeds, but any other advice would be appreciated.

Get a good bit. The Onsrud O-Flute router bits for plastics are fantastic for acrylic. A straight flute router bit is another good one to try, though for acrylic I would stick with the o-flutes.


Nate
Fine Line Automation
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[rlockwood]

Cast sucks, extruded is okay.. Same as all other plastics, take a heavier chipload than you're comfortable with, and don't spin so fast that it melts. Sharp tools with high rake are ideal, which means ones designed to cut wood will usually excel over those designed for metal. FLA's tooling recommendations are spot on, though you likely don't have the RPM to necessitate the single flute; actual routers have a very high MINIMUM rpm, likely several times faster than your maximum.

If you're looking for good finish on pocket floors, you'll need a large radius; think button insert..

[Fred27]

I found the opposite - cast milled very well, but extruded melted too easily. I saved the extruded for laser cutting instead but it also smells far worse than cast.

[rlockwood]

Possible I have them backwards.

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[ger21]

Yes, I've always heard that cast machines much easier.

[Hirudin]

I've done a couple things in *cast* acrylic. What I've done is take my cutting speed and feed for aluminum and either double the feed rate or halve the spin speed. I have a FogBuster and I turn the coolant up a little higher than aluminum as well - I find the resultant cuts are more transparent if they were wet when they were being cut.

On the topic of coolant: if you're using it you may want to peel the backing paper before you do your cuts. The backing paper I've handled breaks apart when it's wet which makes it a bit of a pain to remove. The cut also makes the edges fray. It's possible letting it dry would make it stay together better - I'm not sure as I'm impatient and always peel it ASAP. Small, soaked pieces of backing are worse then larger pieces.

[SCzEngrgGroup]

If this is just plain acrylic sheet, it machines just fine with 2-flute endmills. Coolant STRONGLY recommended. You can go easily 2-3X faster than you can in aluminum. I usually use a small endmill, but any size will work as long as it's sharp. You should get a very smooth edge, with a frosted look. Run a propane torch quick;y over it just enough to melt, it, and you'll end up with a crystal clear, glass smooth edge.

Regards,
Ray L.

[mountaindew]

Yes, I've always heard that cast machines much easier.

In general this is correct!
Cast, extruded, cross linked are general types and a very wide range of qualities of these types!
I have some cast, and extruded that machines perfect and less quality materials that machine completely different.
For my detailed work I use normal 2 flute carbide end mills, I can machine nice parts around 2000 rpm 15ipm
I don't run things real fast mostly because of noise levels in my shop. Also No coolant just vac up the swarf.
You can go much faster feeds with higher spindle speeds, I would guess just watch for tear out at edges.
Also I notice the shorter the tool overhang the better the finish overall. Guessing the carbide cutter flutes are designed to bite into a harder material to help with deflection.
Just a guess

Anyway lots of ways to mill it and you might have to experiment because of grades and types to get best results!
md

[Hirudin]

Another, hopefully quick, note: one hurdle I've had is that it's not easy to tightly clamp thin stock. If you go too tight it'll bend; too loose and it's possible the tool will pull it out of the vise. If possible, it would be good to fixture it in a way that both holds it square and keeps it flat. I bet a vacuum table would be ideal. Some kind of tacky glue on a sacrificial board could possibly work as well. A modular fixture plate could do the job also (I imagine).

[SCzEngrgGroup]

Double-sided tape can work very well with Plexi.

Regards,
Ray L.

[kvom]

I ordered a o-flute bit on eBay and will try that. I do have some extra material to experiment with before making parts. I need to make two 1-off parts from 12x12" sheets, and the second is from a $20 piece of scratch-resistant. It also will get some engraving.

[rlockwood]

Double-sided tape can work very well with Plexi.

Regards,
Ray L.

Just gotta remember to pull the paper off first.

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