Spindle bearing woes

Izzy

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So about a year ago I bought and restored an old McKenzie lathe which the group was great for helping me with the questions I had. At the time I didn't do much with the spindle bearings other than set the oil clearance with shims and plasti-gage. The lathe ran great for the last year and I've made alot of parts with it since I've had it running but just recently I've been getting chatter and it's been getting worse and worse to the point where today I measured .015" play at the end of a 6" part. The chatter was too much I had to do something About it so I tore into it did some investigating. I measured .004" play at the spindle at both the front and back bearings. I also took the spindle out to get a look at things and measure. The spindle measured nice an round everywhere I measured. The bearings not so much... they're pretty scored along with the spindle and the bearings are measurably egg shaped. :( The 2 numbers for the bearings where taken 90° apart, I took a few more measurements that aren't written down. All the measurements are in the pictures Along with pictures of the bearings and spindle itself. What do you guys recommend be the course of action? The bearings where measure with no shims installed and bolts tightened down. IMG_20180926_181630.jpgIMG_20180926_181649.jpgIMG_20180926_181709.jpgIMG_20180926_181731.jpgIMG_20180926_181807.jpgIMG_20180926_181829.jpgIMG_20180926_181950.jpgIMG_20180926_182011.jpgIMG_20180927_010402.jpg
 
I don't know if I'm going about this the right way but I need the machine back up and running and with no advice yet I went out on a whim and stoned and polished up a bearing cap to see where that would get me. Here's what it looks like. Still unsure if I should even be doing this someone out there has got to have a light to shine on this.IMG_20180928_122413.jpg
 
I had the idea to get some Prussian blue and marking the bearing to the spindle I just don't know if this would be a good idea or not. There's definitely material that can be taken off the spindle doesn't move at all without shims under the caps. Is it possible to scrape them in new like that?
 
The usual treatment for a saddle bearing is to skim (grind) a tiny amount of material off the cap where the two mating pieces contact (along the "saw line" of the bushing), and then hone the bearing to size. It will never be perfectly round, but you can get real close. If I were to go that route, I would grind the spindle smooth on the bearing contact surfaces, measure it, then grind the cap and torque into place. Then I would use a hone (if compatible with the bearing material) and hone out the bearing to match the spindle plus an oil clearance. That's probably the best one can do short of taking the whole project to a better quipped shop. Edit: if you can separate the bearing from the saddle and cap, you can do the work on a lathe.
 
This is the exact kinda advice I was looking for I didn't know that was an option. Unfortunately I'm just a home gamer and this is my only lathe. The chatter was getting so bad I had to tear it apart to do something! I the only other machine I have is my Bridgeport. I don't mind brining the head stock and bearings and spindle to a shop and having them do the work but if there's anything I can do to minimize the cost or if I can do something with the Bridgeport? The headstock comes right off this old lathe...
 
Oh, I didn't realize the headstock was easy to remove. An automotive machine shop should be able to do the job for you for a price that won't give you stomach cramps. I'd hit the yellow pages and ask around, that should be an easy job to get done.
 
@pontiac428 well that puts me a little more at ease, thank you! So there's nothing that could be done by my hands either on the Bridgeport or with a little elbow grease? If not I'll call around. There's only 2 automotive machine shops in town.
 
Hi Izzy,

You said the spindle binds up solid when you take the shims out.

Use a pair of feeler gauges on either side of the bearing cap to get an idea of how thick the shims need to be.
Make quite sure that they go back on the right way round, the way they came off.
The technique is this rub the saddle and bearing on some abrasive paper, just to make sure the mating surfaces are clean.
Re-assemble the cap and add shims (feeler gauge) until you have the clearance you want.
If necessary get or make some shims of the right thickness. 5 thou brass or steel shim material is quite common.
I wouldn't do anything to the shaft bearing surfaces unless they were really bad, and looking at your pictures they aren't too bad at all.
If anything I would say those bearings have been oil starved at some point.
 
@BaronJ if you look at my measurements for the spindle its got a high spot in the middle of the front bearing surface and I feel like this should be addressed while I have the spindle out. It's hard to see in the pictures but the spindle is pretty badly scored as well, my finger nail catches everywhere on it. I thought of maybe polishing it up with some Emery cloth using the shoe string method. I think I would have issues trying to set oil clearance when the bearings and the shaft aren't quite round, it would be easy to get false measurements.
 
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