Question on endmill for ABS

Mostly Printed CNC - MPCNC Advice
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Hello all, I am extremely new to CNC and have been gathering parts for the Primo. I have reached the point where I need to get some endmills. My goal is to mill out some 1/4" ABS plastic sheets to create a faceplate to use on a box I am making. I will be using the Makita RT0701C on my build.

The faceplate will be about 6" x 9" and has some 3.5mm round holes for screws along with some other larger round holes for buttons, etc that will be all the way through the material. There are a few other square “holes” that will not be all the way through, these small square cuts are about 10mm x 4.5mm and would be about 4mm deep into the 1/4" material. They will be used for seating other components into the bottom side of the faceplate. Based off what I have learned, I know you cannot really mill a square hole (and that is not a problem) but I am trying to figure out what endmill I should be looking at getting.

My questions are:
What endmill or bits would you recommend?
Can I do the whole thing with one mill/bit? (I would rather not change bits unless necessary)
Does 1/4" or 1/8" shank matter? I know the Makita comes with a 1/4" collet

Thanks for any help you can give. I can provide more info if necessary, just let me know!

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ABS plastic isn’t too demanding, just make sure that you’re moving fast enough not to melt it, because if you’re melting it on the bit, it’s going to make a terrible mess.

The 1/8" single flute mills in the V1 shop are good for that, the 2 flute ones should be okay as well, maybe a bit faster. Ryan also sells the 1/8" collet for the Makita. I’ve also used 1/4" to 1/8" adapters from Amazon, and they work okay, you have to be careful to seat them correctly in the 1/4" collet is all. Overall, the 1/8" collet is better.

Remember that you can’t get a sharp inside corner, it will be limited by what the bit can get to for the square holes.

Chances are the choice of bit isn’t going to be too critical for ABS plastic, but try some different settings first to make sure that you get a successful cut

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I actually ordered the 1/8" collet adapter from Ryan today and ended up ordering some cheaper 1/8" single flute mills to test out and see what they do. I have a lot to learn so I need to get some time on the machine. Thanks for the reply.