Spindle health assessment

[durableoreo]

My mill (G0755) spindle sometimes rattles. If I touch the spindle nose when this condition occurs, I can feel a slow lane amplitude vibration. Maybe less than 10 Hz. It usually shows up to when I'm using an endmill larger that 1/4" or drills larger that 3/8". When drilling, the rattle does not show up under all drilling conditions. If the feed is aggressive enough and the grind is fresh, no problem. Milling side ways always produces the rattle

I put an indicator on the spindle nose, when stationary, mag base on the spindle gearbox. If I push hard on the drill chuck (6" lever) I get 2.5 thou deflection but it only comes back to 1 thou. Same if I push. So some of the deflection is elastic and there's is a dead zone? An I right to interpret this as slop in the bearings?

The bearings are 30206-P5 and 30207-P5 tapered roller bearings

If I run at top speed 2000 RPM for 20 min, the spindle nose warms up to about 100 oF. It's very warm but you can hold your hand there. I've had the mill for about 2 years but i didn't notice at first. I do a lot with 1/4 endmill and smaller drills, which does not exasperat the problem. It may have gotten worse but I was so green back then that i don't trust my memory

I am not excited about tearing into this. It's it normal? More preload? New bearings? Any input is welcome.

 

[Aukai]

Mine rattled from the splined draw bar, not the spindle.

 

[sdelivery]

More preload , about 130-160 f

 

[markba633csi]

Your measurement might be faulty since normally you have some quill movement w/ respect to the head casting
Did you lock the quill before taking the reading? Keep in mind that the quill lock might still allow
some quill movement in some directions
The ideal would be to fasten (somehow) the indicator to the quill itself

 

[durableoreo]

Your measurement might be faulty since you have quill movement

Good point. I measured again (2nd photo) and found about 0.000,075 in either direction with no dead zone. If there is any non-elastic movement, it is too small to measure this way.

I also measured the radial play. I could not measure any vertical deflection at all, even with the 50 millionths indicator, and prying as hard as I thought I could get away with.

OK, so that is consistent with the bearing temperature readings. But is there anything I can do to reduce the rattle? Is it possible that I'm causing the problem by running a tatty endmill for roughing? Or a few of my drills aren't cutting on both flutes?

 

[Janderso]

The spec for spindle TIR on my heavy duty Sharp mill from the factory is .0002”
FYI.

 

[durableoreo]

Mine rattled from the splined draw bar, not the spindle.

This is a good point. I searched for other threads (listed below) and apparently NOISE is fairly common in these import mills, even PM mills.

Options:

1. high-tack grease on the splines
2. Keep the drawbar centered
3. oil spindle bearings (if not greased)
4. loose parts in the drive train, like idlers
5. adjust lash of back gear (BP heads)

Other suggestions were to add flywheel before gearbox and upgrade to 3-phase motor, but those are upgrades, not fixes.

I looked at my roughing endmill under a microscope and 3 of the 4 corners were chowdered. After I replaced it, the noise was less but there's still a rattle. I'll modify the drawbar and grease the splines, too.

PM-727M spindle rattle/vibration

Hi all, I have a PM-727M and the spindle (or whatever parts attached to it) rattle like crazy even under the lightest loads. I can hear and don't think I am imagining "rattle" and vibration even when ZERO load. I do understand, it is a tiny mill and that the cutter, feed rate, RPM, depth, type...

www.hobby-machinist.com

Spindle noise questions Enco 100-1525 / Jet JVM-836

I recently got an Enco 100-1525 2/3 copy of a BP mill (appears to be the same as a Jet JVM-836. At some speeds and when loaded, I'm hearing rattling noises from the head. When the head is tilted, the rattling gets worse. When I got the machine, I ran it over all speeds (3500 max) and everything...

www.hobby-machinist.com

BAD NOISE

Hey guys so i have a grizzly 8x30 mill before this i have only used my mini taig mill oh and i am not a machinest i am a knifemaker so i don't know a whole lot about these machienes so anyway my grizzly was fine for a while i just used small stuff like 1/2 and below endmills and a slitting...

www.hobby-machinist.com

Quieted a noisy Bridgeport (clone)

I watched this video, and realized that my mill sounded exactly like his, before the fix. He explained that the gears are kept slightly apart, or some such, and if you only do this thing, it will fix it. I don't completely understand what is going on precisely - maybe someday I'll have to...

www.hobby-machinist.com