[Source] Spindle Bearings

Bamban

Bamban

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A friend came over to use my 1236 lathe, as he spun the spindle he noted some noise that he thought was bearing noise. My hearing is so badly deteriorated that I never heard what he claimed to be a subtle knock.

First of all, what is the best way to quantify the noise?

Secondly, assuming I might end up replacing the spindle bearings, what ANSI, ISO, DIN rating would give me the least runout? According to the only document, every bit of 5 page total parts breakdown, I got with the lathe, the bearings are 30212, and 30210.

Thoughts?


nez
 
Metric bearings don't use the ABEC system; they use a P-rating. It will come down to how much money you're willing to spend because below P5 (equivalent to ABEC-5) these bearings get expensive. By the way, as the number gets lower the accuracy rating goes up in the P-rating system. For example, a P4 is has tighter tolerances than a P5.

Given the probable accuracy of your spindle, I would think a P5 would be adequate. I suggest you buy your bearings from a decent maker like FAG of Germany. You can email them to discuss the accuracy level you require; I have found them to be quite responsive.

By the way, "bearing noise" is usually a poor indicator of bearing condition. If the bearing is truly the source of the "noise" then its pretty far gone and there will be other indicators that they're shot, like really bad run out. It may just be that they are dry, in which case you have an issue with the oiling system. It may also be that the preload is not adjusted correctly.

I would suggest you check your spindle concentricity. If it is way out then try adjusting preload. If it is still out then your bearings need to be changed. I would trust this before I trusted someones ears but that's me.
 
Tozguy said:
This is an example what I would use to get a better listen and diagnose unusual noise or suspected bearing 'noise'.

https://www.kmstools.com/neiko-mechanics-stethoscope-4060
Click to expand...

These are good and I have one that I got from my father. But, you can also use a plastic handled screw driver... they actually work extremely well! Just cup your hand around the plastic end and hold it up to your ear and touch the metal end against what you want to listen to.

YMMV,
Ted
 
I am with Mikey. Check things out first to determine if the spindle is the problem. If the spindle runout and preload are good, there are other bearings between the spindle and motor. Any of these could be making a noise.

If the noise is a bearing, I would want to determine which bearing before I start tearing things down for replacement.
 
Gents,

Thank you for the prompt responses. I will do more testing. If and when I need to replace the bearingI would definitely give the German company a shout.

I read about bearing pre-load, what appears to be the consensus on the proper test, temperature test or axial radial test with imdicator.
 
In my experience, you will 'feel' bearing problems as a vibration way before you hear them. Any sort of clunk or click, I would look at gear train first and make sure nothing is stuck between gear teeth. Even grease build up can be felt as a 'thump'
 
I think Fafnar or something like that is also a good bearing. If you want to help pin down where the noise is the long handle screw driver is a good one. With hearing loss, the plastic handle against the bone just in front of the ear. My father taught me that one a long time ago when checking valve train, and bearing problems in car engines. Was one of the most accurate ways I found to figure out where noise under the hood was. Great for checking water pumps also.
 
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