[Louis_Cannell]

Louis, what spindle are you using?
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My normal spindle for cutting acrylic is a 500w DC variable 0-5000rpm I also use a 2.2kw VFD water cooled but seldom use for acrylic if I do up feeds as required.

[Jon.N.CNC]

Well you have some really varied replies here. I would suggest you start at 8k. As mentioned be aware of what the chips are doing. They should be individual curls of acrylic, if they begin to fuse together, increase feed.

You could also try using water to cool.

[ericclinedinst]

well folks. I guess I tried everything BUT having my spindle turning the bit in the proper direction... I guess at some point along the line of hooking everything up and testing and retesting during machine assembly, I got two of the wires on the vfd to spindle backwards. DOH. So when I was giving my machine a M3 command I was in reality getting a M4. Ha ha. Apparently that approach is much more forgiving in wood than it is in acrylic. <facepalm>

Attachment 319282
The wires to the right are what were switched. 1 got swapped with 3 somehow during my bench testing and putting it on the machine itself.

Attachment 319284
Cut comparison. Apparently when the bit goes backwards all you get is broken bits and melty plastic. Aha


Actually getting feathery chips now. Instead of molten BB's

Attachment 319288
Shocked that the old way was even able to cut anything out at all.

Attachment 319290
First acrylic part hot off the press!!

Attachment 319292
Attachment 319294
Attachment 319296
Bottom part of my dust shoe complete!! Now I have to venture an hour away to go get more acrylic to finish the job. At least I know where to find it cheap. Hah

Moral of this story is make sure your spindle is spinning the proper way kiddies.

[gfacer]

LOL. The O flute would really work against you in that case. Amazed it worked for even 5 seconds. Glad you found the problem.

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[gfacer2]

So spill the beans, what feed and speed....

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[ericclinedinst]

63-520 Onsrud "O" flute (3/16" bit"
16k rpms
64 ipm
.1 depth of cut
conventional cuts all the way
30 degree ramp in

So smooth. I am so happy

[Jon.N.CNC]

well folks. I guess I tried everything BUT having my spindle turning the bit in the proper direction... I guess at some point along the line of hooking everything up and testing and retesting during machine assembly, I got two of the wires on the vfd to spindle backwards. DOH. So when I was giving my machine a M3 command I was in reality getting a M4. Ha ha. Apparently that approach is much more forgiving in wood than it is in acrylic. <facepalm>

Attachment 319282
The wires to the right are what were switched. 1 got swapped with 3 somehow during my bench testing and putting it on the machine itself.

Attachment 319284
Cut comparison. Apparently when the bit goes backwards all you get is broken bits and melty plastic. Aha


Actually getting feathery chips now. Instead of molten BB's

Attachment 319288
Shocked that the old way was even able to cut anything out at all.

Attachment 319290
First acrylic part hot off the press!!

Attachment 319292
Attachment 319294
Attachment 319296
Bottom part of my dust shoe complete!! Now I have to venture an hour away to go get more acrylic to finish the job. At least I know where to find it cheap. Hah

Moral of this story is make sure your spindle is spinning the proper way kiddies.

Lol it happens.. i did this for a couple of hours when i set up my latest machine wondering why all i could make was smoke.

[ZamcoLaser]

Eric, that looks great. What have your results been when using the acrylic for this project? I made a dust shield almost identical to the one that you have and found that the acrylic kept braking at the joint that tightens it to the spindle. I wound up using clear polycarbonate in 1/2" and have had zero issues since.

[Louis_Cannell]

Tip with acrylic is Dichloromethane it welds acrylic strong as the original solid mateial and with good joints they disappear making it one piece, extremely quick and strong I even use to make T_slot brackets for 50kg hold downs and the acrylic will break at other places before the joint moves. This is 4 layers of 5mm acrylic welded in the horizontal and welded the joint is just as strong as the material if not stronger, the clamp has had months of abuse and high tension and the only one of 10 to fail but not on the joint.