Feeds and speeds for ABS or PLA on a Taig mill w/miniature end mill

[theclay]

Hello folks,

I'm trying to mill out details in a 3D printed part using a Taig CNC mill (1100-10000 RPM, 30 IPM max (maybe)). The end mills that I'm using are .018" diameter 2-flute square Carbide TICN end mills with a .09" LOC (I'm doing some pretty small details).

I don't have any access to coolant capabilities or better equipment and need to figure out how to run the job without the end mill breaking. I've tried (among other attempts) 10000 RPM at 3.83 IPM with .009 DOC at 1.915 IPM plunge in PLA, which ended in breaking the end mill early in the operation from apparent melting and gummy gunk in the flutes.

I understand that ABS is a much better material choice (at least as far as 3D printable materials go) for milling due to the higher melting/glass point, and so I was wondering, given the capabilities of the mill (or lack thereof), and the absence of any coolant/continuous air application, what feeds, speeds, DOC, plunge, and other settings will solve my problem.

I've been warring with this issue for some time now, so thanks for any and all help in advance!

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[awerby]

You're asking for trouble using a bit that small and a material so liable to gum it up. The fact that you don't have any way to cool things down pretty much dooms you to failure, or such a slow process that it's unrealistic. Have you thought about using a better printer that can get those details without having to machine them? There are resin-based printers which can produce much better detail than the FFF process can approach. Check out the options at Shapeways, like "frosted detail plastic": Frosted (Ultra) Detail Plastic 3D Printing Material Information - Shapeways

[theclay]

Thanks for the reply - I've ordered some of the parts through Shapeways with the material you linked - I had no clue that they had a material with that level of detail available. Nonetheless, those parts in that material may end up being too fragile and inflexible for my application. I've been inspired by another thread (http://www.cnczone.com/forums/genera...76650-cnc.html) to try again using manually applied ethanol or isopropanol. Given that coolant method, what spindle speeds should I be able to safely run in ABS, given temperature concerns? I've been getting the relevant other settings from the FSWizard (FSWizard - Free Advanced CNC Speed and Feed Calculator). Thanks!

[awerby]

I don't think that speeds-feeds calculator will do you much good, since it's all about metals. The closest it gets is "hard non-metals", but you've got soft non-metals. But you've got a better chance with ABS than with the PLA, since it's not quite as likely to melt onto your cutter. The alcohol should help with that too.

I'd say run it at 10k rpm (as fast as the Taig will go) and using the same settings (3.83 ipm, .009 DOC etc) give it a try. If the tool breaks anyway, try going slower and lighter (I hope you've got a lot of those little tools...)

[theclay]

I ended up having success using those same settings in ABS! I squirted it constantly with 70% ethanol during the whole operation, and that definitely helped with the chip clearance and temperature issues. Thanks again for all the help!

[awerby]

Congratulations! It's good to know this is even possible...