Drill / Mill Spindle-to-Pulley Spline Fit

[jdeng]

yeh I ordered one this morning. i just pulled it and it feels totally fine. there's no play between the races at all. I do happen to have the 7007 ACB that was in the spindle that could be a drop-in test if I'm impatient...I think?

In the meantime, some more debugging below:
View attachment 20240908_5915.mov

 

[durableoreo]

I've had howling wheel bearings that seemed OK in my hands. So finish the replacement, just in case this really is the problem.

 

[RJSakowski]

You can download a strobe app to your phone. It may help to identify the source of the sound. The frequency of the rattle seems too low for a bearing. It sounds more like a belt to me.

 

[jdeng]

Oh! That’s a good theory considering I didn’t hear the rattling using the low speed belt. Never thought it could be the belt itself. Why would a belt sound like that?

Not much wear, I’ve only got about 15 hrs on the machine. I can’t promise I didn’t get my greasy hands all over it though.

 

[jdeng]

For what it’s worth:

• The low-speed, no-chatter belt is a timing belt, and
• The high-speed, has-chatter belt is a banded v-belt

 

[Ischgl99]

The belt could have a broken band in it, but still look good. Since you are getting it with the high speed belt, but not the low speed, it would be worth changing that belt.

My concern is the movement of the pulley you showed in the video, I would not expect any movement, but since it is a single bearing design, maybe there is supposed to be some. What bearing was in the pulley assembly when you showed the one that came out of there in your hand? You can’t use an ACB in there unless you have two, one bearing would be loose similar to how the pulley was flopping around in your video.

 

[jdeng]

Ah sorry that was confusing. In my video I removed the bearing and installed the bearing-less pulley on the spindle to see if I could replicate the knocking.

New 6007 bearing arrives tomorrow and I’ll thoroughly inspect belt today.

edit: typo

 

[markba633csi]

I don't think it's a bearing issue- I believe you have already identified the issue as being slop in the splines- that would cause
the rattle you are hearing.
You also may have a loose fitting quill

 

[Red96]

Drawbars can make a rattle noise if you run the mill with no tooling in the spindle.

 

[jdeng]

thanks everyone. replacement bearing gets here tomorrow but wanted to update on what i've done.

• soaped and lightly scrubbed the v belt. rinsed with isopropyl and baked in the gravity oven at a low temp for 30 minutes. No change.
• installed the pulley bearing assembly on a precision shaft and tried to find play. no play.
• found the thickest grease I could find and slathered it on the splines and.....no more chatter.

I'm now firmly with @markba633csi that the slop in the splines is the culprit. but, when installed, the slop is only evident in rotational lash. Assuming I'm not changing direction I would hope that it isn't an issue...so why is it? The only thing I can think is that as the pulley is being driven the belt slips and the backlash is reintroduced. Bad theory?

I'm just going to go ahead and order a new pulley. Grizzly has them in stock, they're $60 and I can get it faster than wading through their warranty back-and-forth