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  1. Increase feed rate a bit. With that type of pass in acrylic you want to be getting chips that are quasi snowflakes to proper chip form. Dust is a sign that you are cutting to slow and you will deal with melt and it will cause problems. Next is this cast or extruded acrylic (easiest way to tell that I know of is almost all extruded has a translucent protective covering and cast is white) When I am surfacing 1212 I am going between .75 to 1.5 mm deep with a 3 flue TCT MG end mill and running it at about 14K and 2.3 m/min and getting rather nice finish. Acrylic is a problem child in that it will melt easily IF F & S is to slow (even cast will start too but requires really slow).

    Cutting plastics requires testing and learning what works, due to large number of variables that are out there. Type of plastic, type of end mill, S & F's; these all play a part then add how rigid is the machine and things get interesting.


    PS From everything I have seen I agree with ADCNC that is redeposit of plastic on passes after the original cut due to too slow of feed rate.
    Last edited by m.marino; 22-12-2012 at 04:39 PM. Reason: adding PS

  2. #12
    I don't think it is just the feed and speed, since the X axis direction is fine at the same speeds. I suppose increasing feedrate might reduce the need for better extraction though? If I push feedrate too high without increasing RPM of course the bit will deflect or break, it is only 3mm dia.

    I can probably improve dust extraction (for one, I emptied my vacuum!). I'll have a play and let you guys know how I get on.

  3. #13
    Okay well I actually found that my entire Z axis was loose from the X axis. Strangely though I'd have expected that to make the X axis cut poor but that one was great, lol. Still it couldn't have helped matters. I've also made a modification to improve dust extraction. I haven't tried another cut yet, I'll do that tomorrow.

    I'm also considering getting a more suitable tool for cutting plastics. Looking at the Cutwell Tools site.. what do you think is better for acrylic they have 45deg Helix flutes (do these extract the chips better?) plus some YG single flute HSSE and some Karnasch cutters. Are the Karnasch worth the extra money?

  4. #14
    Quote Originally Posted by Tenson View Post
    Are the Karnasch worth the extra money?
    Never used any to cut plastics but have in Ali and they are excellent cutters. Best finish I've had from any brand cutter so far.

  5. If your looking at cut-wells range have a look at the YG1's Alu-power, summat like a 6mm 2flute should give you good results but with these you need to keep the RPM down or the feed up when cutting plastics. The bests cutters I've used so far are OSG and M.A. Fords for Aluminium and plastic but that all depends on your budget and how sturdy your machine is.

  6. #16
    Unfortunately I need to use a 3mm bit for this work.

    Do you think the Alu-Power are better for plastics than the HSSE ones? Cutell seem to suggest the HSSE are better for plastics.

  7. Ive never used the hsse cutters but i dont see why not! Give one ago.

  8. #18
    Quote Originally Posted by Tenson View Post
    Unfortunately I need to use a 3mm bit for this work.

    Do you think the Alu-Power are better for plastics than the HSSE ones? Cutell seem to suggest the HSSE are better for plastics.
    Most of the Alu-power are HSSE cutters and the single flute certainly are. That said other than the Karnasch I think HSSE give a better finish in Ali than carbide does.! They just wear quick.

  9. That can also be a byproduct of feeding to slow as you get melt and fusing at the top of the piece being cut. Just something that came to mind as I was cutting and cleaning up a new jig for the machine. When doing finishing surface profile with a 6 mm 2 flue I am normally running at 2.25 m/min or slightly faster (up to 3m/min on really thin finish passes) and that leaves a very nice smooth finish that polishes easily if needed.


  10. #20
    Any comment on the 45deg helix cutters? Is assume this is done to get better chip evacuation? Worth a go?

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