Acrylic - v cutting bit speeds and feeds

[DGDesigns]

Any recommendations for feeds and speed using a v bit on cast acrylic?? I am using 1/2" thick material and need to v groove the outlines of letters and borders approximately .25" depth. I also need to do a perimeter cut completely through the material
Thanks

 

[m giese]

a little more info would be helpful, such as who's and what bits are you using, what is the method of hold down. Some machine info might also be helpful..

Assuming the v bit is a double flute, I generally will cut at a spindle speed of 18000rpm, feed rate of 160-180ipm, and usually take a depth pass of .050" per pass, this is fast enough to keep heat down, which prevents reweld. keeps vibration down, and the CEL of a .050 z pass is actually .070 assuming the bit is a 90 degree v bit, X2 due to the double flute.

For the perimeter pass, i generally use an onsrud 63-744 quarter inch diameter, single edge o flute, upcut. Feed at 220 IPM, depth per pass .100", final depth finish pass at .050"

as a general rule of thumb, your depth pass should not be more than 1/2 the diameter of the bit. years ago I did the chip load calcs, but settled on using these settings, they give me pretty good results.

Your results may very, but this works for me.

 

[DGDesigns]

Thanks for the feedback. The guy I am using has a Shopbot with vacuum hold down. He was unsure where to start with speeds and feeds cause he normally cuts HDU molds. I will get the tooling recommended to avoid the long learning curve. We will be doing a test cut on scrap pieces to fine tune things, but had no idea where to start. We have a 90 degree bit but he did generate a 3D image of the cut path and said it may look nicer with a 60 degree cutter.