South Bend 9" Pre-C Spindle and Spindle Bearing Galled/Scored

MasaAMD · May 26, 2019

Hello all!
This is my first time posting. I recently acquired an early C version SB9 that was in great condition overall. Every piece until the spindle and headstock bearings has only needed minor cleaning. This is my first South Bend lathe and I can see why these lathes are so sought after. It has been a great learning experience so far but I am at a point where I would like to consult others opinions on this issue.

This lathe has the cast iron bearing surfaces that have been badly galled, resulting in damage to the spindle bearings surfaces as well. I stoned a small portion of the spindle, but I am apprehensive of going any further until I have other opinions. Also, I am seeing mixed results on honing the headstocl bearings and using stones in general due to loading.

Here are pictures of the damaged bearing surfaces:

MasaAMD · May 28, 2019

Also, here is a little more info if helpful:

The serial number is 66212, and 120S6S is cast into the inside of the bed near the tailstock. There is no catalog no. on the nameplate only the swing (9") and bed length (3 1/2'). It also has a soft 1-1/2"-8 spindle, normal right hand lead screw and top mounted oilers.

Just in case the spindle is not worth saving (spindle taper is damaged as well), I also picked up a good condition one from a later year 9".

iwananew10K · May 28, 2019

there may be a slight diff in spindle length...what type thrust bearing do you have?

chances are if you just clean it up good,set clearance and oil it will be fine....had ones that looked as bad or worse that still did fine work.

ps- leave the headstock bores alone, there may be adhered cast iron deposits on the spindle- that can be removed carefully, but leave the bores be.

MasaAMD · May 28, 2019

Thank you for your reply. I have the 3 piece ball bearing type thrust bearing with a fiber washer in the between the collar and rear bearing. On a side note I did order the needle bearing upgrade from McMaster to replace the old fiber washer. I can grab measurements on the thrust bearing, since I do not know if there are any differences throughout the years.

The spindle I ordered is hardened and micro polished. It also has a flange on the front just behind the threaded shoulder. I believe it was for a segmented cast iron bearing headstock.

Unfortunately before seeing your reply, I did kiss all the sharp edges in the headstock bores with a file (very very lightly) and then a hard Arkansas stone. My worry was sharp edges from imbedded material being passed over the felt grove and shim section. Aside from that would it be advisable to use green scotch brite and mineral spirits to thoroughly clean the bores?

I will post updated pictures in a few hours.

iwananew10K · May 28, 2019

you'll be fine...if you have the 3 piece thrust bearing I believe you can swap spindles without issue....easy enough for you to tell.

BTW- do not use scotch bride on precision surfaces, it contains silica and can embed making whatever it embeds in into a lap.

MasaAMD · May 28, 2019

Thank you very much for the heads up. What would you recommend to thoroughly clean the bores? Stiff nylon or brass brush possibly?

iwananew10K · May 28, 2019

That should be fine...just go easy on the bores.

M.B. Naegle · May 28, 2019

I'd be curious what might have caused the galding so it could potentially be corrected. If someone just never oiled it, that's easy to remedy, but it would be good to make sure the oil points are not clogged.

Does this machine have the jack-shaft assembly? If not, it's highly likely someone ran a motor directly to the spindle and over-RPM'd it.

MasaAMD · May 28, 2019

I'm not sure how the damaged occurred but I suspect lack of proper lubrication. Also the felts were rock hard and there was lots of debris present.

Here are new pictures of the cleaned bores. The forward bore has significant damage throughout the entire bearing surface but even still from what I've read on here is that these bearings are extremely forgiving. The rear fared much better. The axial scoring is from when I pressed out the spindle and the embedded cast iron scored the surface.

My next concern is will these cast iron surfaces damage a hardened spindle with perfect bearing surfaces under normal operation with proper lubrication?

iwananew10K · May 29, 2019

no damage will be done to the new spindle...once installed and the clearance set, if you keep it oiled the oil will fill the scars in the bores and there will be no metal to metal contact in operation.

MasaAMD · May 29, 2019

Makes sense and that's great to hear. I'll post updates once I receive the new spindle and have everything put back together. Now I just need to finish cleaning the bed and build a new bench. Unfortunately the previous owner wanted to keep the original bench but I have a nice butcher block top ready to go.

Kevin T · May 29, 2019

Great to read that this is not a huge issue to worry about for our vintage machines! When I saw the pictures I was thinking ouch but reading the analysis from many of you is very comforting.

apcdoxa2 · Nov 10, 2022

Hi, i recently adquire a pretty damaged South Bend model A precision lathe. the headstock bearings full galled also the spindle.
i haven´t the resources (due to no specialized workshops near to me and in minor order economically) to repair it in the correct way.

my questions:
1 are the SB model A headstock bearings originally babbitted or cast iron only?
2 could i babbitt these bearings?
3 could i apply babbitt as a minimal soldering layer with torch and wired babbitt alloy?
4 may be exist another well knowed viable option? (needle bearings, bronze bearing)

Best regards from Maturin - Venezuela
sorry for bad english

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