Getting cleaner edges

Hi Everyone,

I’m still getting terrible edges. Here is an example from a sheet of abs plastic. I’m using an 1/8" flat end mill upcut on this current piece. It was a brand new bit when this carve started. I’m using the dewalt 611 set on 5 with a cut speed of 800 mm/min.


I don’t think you need the 611 set all the way up to 5 for that, are you ending up with plastic melted on the bit or inside the cut areas?

Precise Bits has a feed/speed testing procedure that I sort-of follow whenever I use a new material and/or bit style. It lets me waste just a little of the material doing 4" lines and 1" pockets, which lets me see not only how much chatter there is, but also lets me see edge and bottom quality. I would suggest dialing your setting down and doing something like this before trying a full-size carve:

The only plastic I’ve cut is 1/8" acrylic mirror, but the settings that I found that worked for my 4 flute upcut bit are .020" (0.5mm) DOC, 50 IPM (1270 mm/min), and 611 set to 1. Those settings gave me a beautiful finish with no sanding necessary and nothing stuck to the bit or in the cut channel.

Thanks Robert. I probably am to high. I need to add a bit with more flutes as well.

There’s a lot of people who like to use single-flute bits for plastic. It’s slower, but I think it probably allows better chip removal. The only reason I use the 4-flute is because I bought a pack of 5 and am really loving them. Unless you’re doing production runs, I’d suggest just using what you have and finding whatever works best for you. :smile:

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