Spindle Siezed

The other day I ran my 10L on the highest speed for the first time and after about 30 seconds the spindle siezed up, suddenly enough to spin off the chuck. It was surprising because I have been using the lathe for a few months without any problems, but on lower speeds. I thought that it would free up after cooling off but it did not, the only thing I can do to free it is to loosen the front bearing cap.

It is a 40's model with segmented iron bearings, and I'm using Mobil velocite #10 in the spindle. When I set it up a few months ago, the front bearing clearance was at 0.0012". I can still read the same clearance now even though it is siezed. I tried adding a shim, and I was able to get it turning, but the clearance is up to about 0.0030.

Any suggestions?

Make sure all the other shafts in the drivetrain turn free.

Just out of curiosity, how do you "measure" the bearing clearance in a seized bearing?

But, back to the issue: If you determine, as suggested above, that the rest of the gear train is not jammed up I think you're going to have to pull the bearing caps and see what's going on. Most likely the "front" bearing is galled from meta-to-metal contact. If you're lucky, you may be able to clean that up with an India stone (very fine and hard) or fine diamond file. Lift the spindle out out and check the bearing bores. Try to clean up any displaced iron. Probably the spindle journal is messed up as well but you can stone that smooth enough to use by putting the spindle back in place and turning it at its slowest speed while lightly applying the stone or diamond to the spindle and flushing it liberally with oil to carry away particles. (The spindle can be rotated under power even without the bearing caps in place.)

Be sure you mark the caps for proper orientation so you can get them back in their original positions.

Recovering from your adventure will take some time but it can be done with some patience.

As you have an older 40s era 10L IMO .0012" is too tight...especially considering it undoubtedly has "some" wear.

.002-.003 is more in line...if it uses too much oil at thoses clearances try using ISO32 oil instead of 22...that's what I did on mine and nary a problem...it ran perfectly.

BTW- if your spindle is seized and you still read clearance you are either pulling too hard or things have gone egg shaped.

If you're still seeing clearance at the nose, maybe it's seized at the other end. Try the broomstick test there and see if you still show clearance.

It is definitely the front bearing. All the gears are disengaged and it is still frozen even when I remove the rear bearing cap. I can feel the change in friction as I tighten the front bearing cap bolts.

The bearing / journal was almost perfect when I installed it. Now I see there are a few iron nibs stuck on the spindle -- I smoothed them out with a diamond stone and it is still siezed. Otherwise the bearing and journal look fine.

I don't know why there is still clearance. Something must be pinched from the sides. I'm not sure it could have distorted into an egg shape, as it was working fine before and it didn't heat up enough to even be warm to the touch.

How you mount your indicator can make a difference...flex is everywhere.

If you have a mag base stick it directly to the headstock and see if your readings change.

Suggest you drain the reservoirs, flush and re-fill with Mobil One synthetic engine oil, 0W30 grade.

This worked for me.

Alright, I got it working...

iwananew10K said:

How you mount your indicator can make a difference...flex is everywhere.

If you have a mag base stick it directly to the headstock and see if your readings change.

Click to expand...

Yes! I had been taking the measurement incorrectly and the "clearance" I had seen was actually flex somewhere. So I probably had insufficient clearance here which explains the failure.

Dobermann said:

Most likely the "front" bearing is galled from meta-to-metal contact. If you're lucky, you may be able to clean that up with an India stone (very fine and hard) or fine diamond file. Lift the spindle out out and check the bearing bores. Try to clean up any displaced iron. Probably the spindle journal is messed up as well but you can stone that smooth enough to use by putting the spindle back in place and turning it at its slowest speed while lightly applying the stone or diamond to the spindle and flushing it liberally with oil to carry away particles. (The spindle can be rotated under power even without the bearing caps in place.)

Click to expand...

I had already tried smoothing out the journal with a fine diamond stone, no luck. So I cleaned the oil off, marked the whole thing with a sharpie, reassembled, and I found a couple tiny high spots right away. I smoothed them out and got it turning again, and added a shim to get to the correct clearance.

So I am up and running again -- thanks guys.

+1 on the recommendation for using Mobil 1 for the bearings at least until things get back to normal. I've used Mobil 1 for other applications where tight journal bearings have been having a problem and it's what I use in my 10L. I was going to recommend that to you but recommending a detergent oil usually ignites a firestorm about "proper" oil here on this forum.