Hello everyone,
I was wondering if anyone has any experience machining cellulose acetate. I understand it can be a tricky material.
Thanks!
Sam
How thick is your material? This stuff us usually pretty thin. The challenge may be more in workholding than cutting parameters.
I have not machined it, but used quite a bit for templates. We cut / scored it with an Xacto knife & broke it on the lines.
I have to imagine it’s similar to PVC, polyester, polystyrene, ABS. Relatively soft with a low melting temperature. I would try a slow RPM and a faster feedrate. Single O-flute bit.
Or if it’s thin enough a drag knife.
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My blocks are on the thicker side from 8mm to 20mm.
I am a total novice so would you mind letting me know what numbers exactly constitute a slow RPM and fast feed rate?
I would start with PVC numbers…
1/4" tool: 10000 RPM 90+ IPM 0.050" - 0.125" DOC 0.125 Stepover
1/8" tool: 12000 RPM 60+ IPM 0.025" - 0.060" DOC 0.060 Stepover
I suspect with a good sharp cutter you can bump the feedrates up to 120 - 150 IPM easily. You’ll have to try it & see what the machine will handle & how it’s cutting. Watch it, listen, look at the chips, If it looks like it’s melting, speed up the feedrate. If the chips are too thin or warping from heat, speed up the feedrate. If you’re still getting too much heat, slow down the RPM.
Unfortunately, it’s not an exact science. Many variables incuding cutter geometry, cutter material, machine horsepower & rigidity, et.al…
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Ok Roger that. Thanks Tod!
Really? Acetate? That thick? What is that used for?
A long time ago, a Chemical Engineering professor told me billiard balls were made of cellulose acetate. If correct, pretty hard.
I wondered too…
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Billiard balls were nitrocellulose (2 centuries ago). Now they are phenolic resin, Or polyester resin for the cheaper set.
Cellulose acetate is usually thin & flexible, though not very elastic. Predominantly used for film (movies & photos). Also guitar pick guards 
I had no idea it was available that thick.
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