Are These Babbitt Bearings Still Good?

[Bi11Hudson]

It was general practice with flat bearings to cast them in place oversize enough that a few shims would be necessary on the bearing cap(s). As the bearing wears in normal use, a shim would be removed to snug up the bearing. Of particular importance in this case where the bearing has run dry, the shaft may have spots of bearing material built up on it. When the bearing cap is replaced, this would make the bearing seem to be too tight. The shaft bearing surface should be "pristine", at least as near so as practicable.

From the looks of the photos, the bearing is not too bad and is probably usable as is. Bearing contact is not 100% even when new. Hand scraping a new bearing to about 85% should cover it. If you wanted to be sure, the shaft could be blued, the bearing cap installed, and the shaft spun over once ir twice. If there is less than 50% of the blueing left, you're good to go. Check that the oil holes and any oil grooves are clear and clean. See that the shaft is well lubricated on reassembly. But not flooded. If necessary to build up the bearing some, kitchen aluminum foil makes good shims. Several thin shims are a better chioce than a single thicker shim.

You must keep in mind that my experience as a helper was 50 years ago. And the machines that I (we) were working on were a little larger than a lathe. As an electrician in the Coast Guard during the late 60s and early 70s, I worked with the ship yard mechanics on small ships commissioned in the late 40s to early 50s, rebuilding main motor pedestals and propeller shaft bearings. The experience was a long time ago and my memory should be taken with a grain nay box of salt. But as a general overview, I still have some memories left.

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[projectnut]

My first experience with Babbeting was somewhat similar to yours. The company I worked for had 2 huge ammonia compressors used for refrigeration. The bearings on the 12' flywheels were babbited. They were originally installed in the early 1900's and ran nearly 24/7 for nearly 80 years.

About every 6-8 years an auxiliary compressor was brought in so the compressors could be serviced, and the bearings rebabbited. The flywheels were lifted a couple feet and blocked while the mechanics melted out the old babbit and poured in new. It was quite a job to watch.

Unfortunately there was a powerhouse fire in the late 1980's that destroyed them. They weren't in all that bad a shape, but the cost to have new parts made was prohibitive. They were replaced with noisy (by comparison) screw compressors.

 

[Rannunzi]

Thanks all for all the info! I've made myself some new shims and found the ideal number per bearing so that the play is minimized without binding the shaft. Using the rod test, I've measured 0.001" of play on the right bearing, which I think is acceptable (correct me if I'm wrong). My main concern was going to be that even with all shims removed, there'd be too much play, resulting in the bearings being unusable. If the bearings do get to that point while the lathe is still in my possession, should I make an attempt to re-pour them, or is that the time to just buy a new lathe?

 

[woodchucker]

only you can answer that. if you find the lathe to be in great shape ... and it's what you want, better the devil you know, than the one you don't.
if you outgrow the lathe you may still want it as a second lathe. Having a lathe is great to fix another lathe.

BTW glad things worked out.

 

[wa5cab]

If the bearings get to the point of having all of the shims removed and has more than 0.001" of clearance, that is probably the time to eiither repour the bearings if you are up to it or to replace the headstock. But I wouldn't scrap or part out the lathe unless the bed and lead screw wear is also excessive. And an alternative to re-pouring the spindle bearings is the replace the babbit headstock with a Timken version. The two internal parts of the babbit headstock that don't fit the Timken headstock are the spindle itself and the thrust bearing is not needed. The other parts, if still good, are usable.