I did some feed/speed tests with 3 different cutters (all at 9200rpm):
1.) 1/8" 2 flute ZrN coated from Lakeshore Carbide (item # 350018XRF)
3.) 1/8" 1 flute uncoated from Inventables
Both of the coated ones produced good results, but I was pleasantly surprised by the second one because it’s pretty cheap. I saw some discoloration in the engaged part though afterwards, not sure if the coating wore off or if that is aluminum sticking to it (see last photo).
The Inventables one did not work well at all.
In the picture the first four slots are the same program as the separate set of four slots in the middle of the piece, just with a different cutter. In the first test I tried some lubricant in the second slot, that’s why that looks a bit messier. It seemed to work better without lubricant.
I varied the feeds a little bit and the finish was comparable, so the difference was mostly about noise. What didn’t seem to work so well was taking deeper cuts than the 0.25mm that’s recommended on the website. In the end I’ll probably stick with the recommendation from the web site all around: 9200rpm, 200mm/min feed, 25mm/min plunge, 0.25mm depth of cut. When I tried this last time, it was very noisy with lots of chatter. Since then I got the coated cutters, and they seem to make a difference.