Advice for Plexiglass?

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This topic contains 12 replies, has 6 voices, and was last updated by  Jeffeb3 5 months, 2 weeks ago.

Viewing 13 posts - 1 through 13 (of 13 total)
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  • #34813

    Skrilla
    Participant

    Anyone know any changes in speed, bit size/type for milling 1/4″ plexiglass. I was going to use an 1/8″ flute bit. Is this ok, or should I go 1/16″. It’s for the lowrider plates, no carving, just straight cuts. I’m using the dewalt 660 plugged in for a spindle so no rpm settings available.

    #34818

    Peter A Mills
    Participant

    I don’t have the answer, but will follow to hopefully hear the answer.

    I cut some acrylic last night and the end result was fine, but it got a little hairy. My piece was thinner, I think about 2.4mm (0.93in) and it flexed a lot while I was cutting it. I needed a 12″ diameter circle and I was able to hold it down and got the cut.

    I tried taping it blue painters tape, but it turned out it wasn’t needed. The plastic covering seemed to be enough. Next time, I’ll use a sacrificial board on top to keep it in place.

    I used a 1/8″ endmill. 20mm/s and 0.5mm per pass. Since it went crazy it ended up cutting through a lot more and worked fine. I had 4mm tabs to keep it in place, some of which got cut through during the craziness. I sanded the edge with a palm sander and everything turned out OK.

    1 user thanked author for this post.
    #34821

    Jeffeb3
    Participant

    @Skrilla, let us know how it goes. I want to replace the 611 plate with something see through, but I keep forgetting to go to the sale on the 4th friday of the month. If I remember next time, I’ll be doing the same thing early July 🙂

    1 user thanked author for this post.
    #34823

    David Walling
    Participant

    They sell chip-breaker end mills that are supposed to help with plastics.

    I bought one, but I confess I haven’t used it yet.

    If I have time this weekend, I’ll draw up something and see how it goes. I have some leftover plexi from an aquarium project I can test with.

    1 user thanked author for this post.
    #34831

    Ryan
    Keymaster

    Just do some test cuts, the above feeds and speeds should get you close.

    In plastic too slow will melt, stick to the bit then clog it, then break something, too fast will do the same thing.

    A single flute bit will effectively cut your RPMS in half over a two flute bit. A down cut bit is nice for thin material to hold it down but usually not so good with plastic because it will pack the chips in the cut.

    It really is not very different from wood, just your sweet spot is much much smaller in terms of travel speed, rpm, DOC. Test cuts are essential.

    Foam

    1 user thanked author for this post.
#34833

Jeffeb3
Participant

Any thoughts on what kind of plastic is better for the 611 plate?

#34866

Barry
Participant
Any thoughts on what kind of plastic is better for the 611 plate?

Cast acrylic or policarb. Extruded acrylic will break too easily.

1 user thanked author for this post.
#34872

Skrilla
Participant

Ok, I tried it with same settings but switched to a 3 fluted 1/8″ bit. Speed worked well. I used the y frame model from the prusa remix. I used 5 strategicly placed tabs at 4mm on 7mm plaskolite optix acrylic sheet. No burning, buildup, breaking, or excessive melting. Only issue you can see in the pic. The far hole on top of the base cut through. Other than that it worked well. Could use a little more ventilation though from the fumes generated.

Attachments:
#34875

Ryan
Keymaster

You want less flutes not more, but if it worked, save those settings.

The holes in that pic are all way too big and misshapen for some reason.

#34884

Skrilla
Participant

Crap, I realized where I went wrong. I used engrave instead of hole in estlcam. I made this program before I had gotten used to estl. Boo, but at least the settings worked well.

#34916

Skrilla
Participant

I fixed the estl file then 2nd print came out much better. Here’s a pic oth the 611 plate I cut this morning before work. both still need a little clean up. I dont have any single flute bits, so I switched to a 2 flute, broke the bit, then switched back to 3 flute.

#34921

Ryan
Keymaster

The edges are still pretty rough, I would do some 1-2″ square test cuts to work that out different speeds or depth of cut, they should come out pretty dang smooth.

#34947

Jeffeb3
Participant
The edges are still pretty rough, I would do some 1-2″ square test cuts to work that out different speeds or depth of cut, they should come out pretty dang smooth.

Agreed, but IMHO that looks like it’s probably good enough to be functional for the Low Rider.

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