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Old 08-20-2017, 11:53 PM   #21
DJP
 
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Not sure if this is possible but perhaps an old style clamping kit will hold down the workpiece and rotary table as a single unit during the cut. It would eliminate some of the variables.

When dealing with chatter I usually blame the cutting tool holder first.


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Old 08-22-2017, 10:02 PM   #22
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Default Results with new HSS .188" bit

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.


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Old 08-22-2017, 11:04 PM   #23
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Your main problem is using a drill chuck to hold the tool.BAD IDEA
If you dont have the right size collet then make a slotted sleeve
to fit the cutter and a collet
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Old 09-11-2017, 10:27 PM   #24
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Default Just to tie up this thread

I realized that I should've ended this thread with my last and best experience with the milling of the radius in the flywheel. I never did find what I considered to be a really smooth milling process. However, by using a high quality, small 1/8" milling bit and taking very small cuts, I found the chatter to be almost nonexistent. However, there still was more vibration than I was happy with and I attribute that to the fact that the rotary table has to have the slightest amount of play in it in order to rotate for the radius cut. The adjustment screw has to be backed off by the slightest amount in order to allow the rotation and the poor quality of the rotary table has just enough play to set allow the chatter. Everything is locked down like fort knox and the mill, the universal HF type, does a serviceable job with other processes. Cheap tools are always the most expensive. Sigh.
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Old 09-11-2017, 10:54 PM   #25
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Quote:
Originally Posted by hfguy View Post
Cheap tools are always the most expensive. Sigh.
+1
I now use a 10 inch Hofmann rotary table for this kind of thing and it's a revelation compared with the equipment I was using,

- Nick


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