Page 1 of 1

acrylic speeds at 30000rpm

Posted: Sun Sep 22, 2013 10:21 pm
by atrueresistance
I was wondering what speeds I should be running. The wiki states

Code: Select all

Bit: double flute 1/8" end mill
Feed: 400mm/min
Speed:20,000 RPM
Cut Depth: 0.08"
Stepover: n/a (through cut)
Plunge Rate: 75mm/min.
So translated that would be.

Code: Select all

Bit: double flute 1/8" end mill
Feed: 15 in /min
Speed:20,000 RPM
Cut Depth: 0.08"
Stepover: n/a (through cut)
Plunge Rate: 2.95 in/min.
I don't have a way to limit my dw660 speed, so this needs to be recalculated for 30,000 RPM. I looked for an online calculator, http://zero-divide.net/index.php?page=fswizard, but this states I should run 12,718 RPM. . . Has anyone had luck at 30,000 rpm?

So far I've tried the translated speeds, but with a depth increment of 0.015". The result was melted plastic stuck to the bit, to the point where I'll have to melt the plastic to remove it.

I also tried a cut feedrate of 60 in/min with depth increment of 0.015" which resulted with less buildup. The only buildup was stuck to the plastic and not the bit, but not a clean cut. This was cut short when path varied from previous path cuts causing the machine unneeded stress.

Re: acrylic speeds at 30000rpm

Posted: Sun Sep 22, 2013 10:36 pm
by PsyKo
If you can't reduce the RPM, try lower flute end mill. Single flute will already reduce the heat caused by the high RPM.
A single flute at 30k RPM is equivalent to a double flute at 15k RPM...

Re: acrylic speeds at 30000rpm

Posted: Mon Sep 23, 2013 6:17 pm
by Estlcam
Hi,

if you have no way to reduce rpm or increase feed as required try cutting with lots of water and a little dish soap to keep the router bit cool.

Christian

Re: acrylic speeds at 30000rpm

Posted: Mon Sep 23, 2013 7:41 pm
by atrueresistance
I was spraying wd-40 when using the faster run. I ordered a MLCS 9400 speed controller that was discussed in an earlier forum thread, and can provide feedback once it arrives.
PsyKo wrote:If you can't reduce the RPM, try lower flute end mill. Single flute will already reduce the heat caused by the high RPM.
A single flute at 30k RPM is equivalent to a double flute at 15k RPM...
I'm not aware of any single flute end mills. The wiki does not have any information on a single flute. http://www.shapeoko.com/wiki/index.php/End_mills

I've only found from my research online these types:
  • 2-Flute - Allows maximum space for chip ejection. Used for general milling operations.
  • 3-Flute - Excellent for slotting. Used for general milling operations.
  • 4, 5, 6, and 8 Flute - A greater number of flutes reduces chip load and can improve surface finish, if feed rate remains the same.

Re: acrylic speeds at 30000rpm

Posted: Mon Sep 23, 2013 9:14 pm
by Gadgetman!
Well, there's a 5pack...

http://www.ebay.com/itm/5pcs-3-175mm-1- ... 564a04cd05

And these, from the sme seller is a bit more expensive, but mentions Acrylic in the title:
http://www.ebay.com/itm/5pcs-3-175mm-1- ... 564bc118ed

And...

There was my order off...

Yeah, I know it's Chinese manufacture, but at that price I'm willing to take a risk.

EDIT:
And our favorite eBayer, Drillman1, also has some neat stuf:
http://www.ebay.com/itm/5-1-00mm-0394-s ... 232d29d9d7
That's 1mm diameter, so you can make pretty narrow cuts.
Limited quantity, so...

Re: acrylic speeds at 30000rpm

Posted: Mon Sep 23, 2013 10:35 pm
by Improbable Construct
I cut acrylic at 30000 rpm all the time.
On my machine (which is not at all stock or even close to it anymore),
I can cut through 3/8 acrylic single pass with a 2 flute end mill at 800 mm/min and have nice clean edges.
Your results may vary. The best thing is to get a piece of scrap and try it out.

Re: acrylic speeds at 30000rpm

Posted: Fri Sep 27, 2013 4:25 am
by calica
What diameter endmill?

Re: acrylic speeds at 30000rpm

Posted: Fri Sep 27, 2013 5:26 am
by Improbable Construct
calica wrote:What diameter endmill?
If you were asking me, I mostly use 1/8" endmills, unless I am cutting a large pocket.