Today I tried the new HSS bit. I don't have a collet to fit this size bit so I had to chuck it my genuine Chinese drill bit chuck that HF generously supplied with their mill. Ugh. The results were significantly improved, though still not completely chatter free. I ran the bit with minimal stick-out from the chuck. Everything I could lock down was locked down, except for the adjuster on the rotary table which has to have a minimal amount of slack to allow for table rotary motion. I cut a max depth of .005" on each pass. Dry cut, no lube. I kept my hand on the rotary adjuster constantly futzing with it to keep a moderate amount of drag on the table as I rotated it. This seems to keep the table about as secure as possible while milling. I tried a variety of speeds. I'm running the mill on the high speed setting and found that about the midpoint of the dial seemed to be best at minimizing the chatter. Due to my inexperience and cheap HF equipment, I can't know the RPM and these are pure guesses based on what seems to work best. Anyway, as I say, the chatter seems significantly reduced, but still there and is helped by snail slow rotation of the table. The bit clearly is superior to the cheap Chinese bits I started with. It seems that with a small, quality 188" bit, <005" depth of cut, and very slow rotation, the chatter is significantly reduced. I ordered a carbide mill bit and I'll try that next and with a some cutting oil as suggested. As usual, I'm regretting buying a cheap tool, the rotary tool. I'm thinking there just isn't the strength in the table to dampen some of the vibration and there is clearly a tiny bit of play on the mechanism. I'll try the carbide bit both with and without chain drilling and report on that.
