Cutting SAN plastic(Styrene acrylonitrile)

Bought some transparent plastic 6mm sheets of material. The stuff gums up up my single flute bit like crazy. As soon as the bit reaches about half Depth a blob of material has Attached to the bit and show’s over…

What is the trick With plastics? low feed pr minute and high rpm?

Pardon my MS Edge browser for random Capital letters… :frowning:

I have found, slower RPM, faster feedrate and clear the chips so they don’t melt.

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What rpm, plunge and feed are you running? I’ve had great success with styrene plastic and 2 flute fishtail bits.

What I do know this far:

900 mm/min @17000 rpm is no go.
300 mm/min @12000 rpm is equally fail.

Plunge is 0.1mm

Also I cannot go below 10000 RPM with the Makita currently attached to my X-carve

I’d say push your feeds harder. Also, if you have an air compressor, get your blow-gun and put that nozzle right behind the bit to blast those chips clear right away!

Found the spec sheet on the material - says it goes “soft” just above 70C degrees.

I do not have an air compressor, sadly. Not buying one this month either…
My plan is to drop down to 10K rpm and up the feed rate to 1500 mm/sec and see what happens.
Also I am considering removing the air diverter from the 3d printed spacer ring that holds my Makita in the Dewalt 611 mount. I could use the air flow to perhaps cool stuff down a little, and also clear off some chips in the process.

I am in the process of making a proper dust shoe so I really need this plastic thing cut properly in order to see the bit do it’s magic in the future. :wink:

Next attempt has to happen tomorrow, though, as my non-insulated garage/workshop is not very pleasant at the moment. Queen Winter has decided that -3C is just perfect at the moment and my crappy heater thing is not up to the task.

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I’m curious as to the size of the bit. I normally use 1/16 and 1/32 and I only plunge half the diameter of the bit.

You can do a test and run a series of parallel lines and up your feed on each line and watch for the swarf to turn to unmelted chips.

For styrene, you may want to look into 2 flute bits.

Two-flute would need even-slower RPMs.

10000 rpm and 1500 mm/min is no og. Increasing feed rate for next attempt
Still using 2.9mm single flute bit

10000 rpm at 2000mm/min is not go

10000 rpm at 2500 mm/min With a ball nose bit worked better… not quite there yet…

Using Gwizard and Acrylic plastic as material. My material table does not have SAN so I went with Acrylic.
Using a 2.9mm single flute carbide end mill with 25mm stick out. I can go .7mm DOC (depth of cut) 2.9 WOC (width of cut) 24000 RPM 950 mm/min feedrate and keep the tool deflection in the black. This is a light rough setting.
If I go to full roughing then the feedrate goes to 1400 mm/min with deflection still in the black.
I’m not sure why you are having the problems you are. What is the history of the end mill in question could it be dull.
Do you have a 1/8" 2 flute carbide end mill you could run tests with.
This translates to 3.175mm 2 flute carbide end mill with 25mm stickout. Same DOC and WOC RPM drops to 23,000 and feed rate jumps to 2066 mm/min Tool deflection still in the black. Light roughing

Hope this helps



I am low on end mills at the moment. Supplies are enroute in the mail.
Do you know the temperature point at which Acrylic goes soft? this SAN thing goes soft at 70C which I think is part of my problems…

Got these 3.175mm shank carbide end mills

  • single flute flat end mill 2.9mm WOC.
  • 2 flute ball nose woc 3.18mm
  • 2 flute flat end mill woc 1.6mm

I have not tried the really small end mill but the two others are hardly used at all. Doubt they are dull. The single flute one I have already cut my thumb on. :smile:

Did get the piece cut With the ball nose in the end. Looks like crap but usable. Had to reverse my vac to Clear chips.

Forgive my browser for random Capital letters… Stupid thing…

Thank you for input. I’ll attempt another run when the New end mills arrive.

the info I find so far says the melting point is 160C but I don’t find where it goes soft.

There’s two types of acrylic - cast & extruded. Home Depot & Lowes sell extruded. I had the same issues with this stuff. I got some cast acrylic from a local acrylic shop and it cut beautifully. I used the 1/8" single flute bit from the starter pack at 0.08" @ 80ipm. (although I did babysit it with a shop vac to keep the path clean)

I read a note from Zach saying that all acrylic from Inventables is also cast.

Thanks for the information. I’ll see if I can source cast acrylic locally.

I ran into same problem the extruded gums up easily i had to babysit it and knock the plastic off bit with razor blade while cutting and that was with slow rpms but cast acrylic whole different world cuts clean but there again if you heat it up you will melt it to bit

Yes, extruded will make a mess. Always go with cast.