Odd runout on mini lathe

All discussion about lathes including but not limited to: South Bend, Hardinge, Logan, Monarch, Clausing and other HSM lathes, including imports

Moderators: Harold_V, GlennW

THMguy123
Posts: 7
Joined: Mon Mar 11, 2019 10:38 am

Re: Odd runout on mini lathe

Post by THMguy123 » Tue Mar 12, 2019 11:28 pm

Little update here. I pulled apart the head stock to do some additional testing and when I pulled the spindle out one of the roller bearings fell apart into pieces. Should these things fall apart? The two face ends of the bearings don't seem to be bent at all...

Now I have to try and figure out how to get that other end of the bearing off the shaft! It was on the good end (next to the chuck) too...

So frustrating...

Harold_V
Posts: 17688
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Odd runout on mini lathe

Post by Harold_V » Wed Mar 13, 2019 4:51 am

Can you better describe what the bearing did? I'm assuming that the rollers fell from the cage, so you have multiple loose rollers and an empty cage. Is that correct? If so, they generally do not do that, as the cage holds the rollers captive. What is common is for the cup (the outer race) to be separate from the cone (the inner race and rollers, including the cage).

In describing the face ends of the bearings, it might help you to know that bearings are heat treated to beyond 60Rc. They don't bend. If adequately stressed, they will shatter instead, but they're known to absorb a lot of abuse. The cage is most likely not hardened.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

John Hasler
Posts: 1271
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Odd runout on mini lathe

Post by John Hasler » Wed Mar 13, 2019 8:45 am

I don't think we know that he actually has a problem with his spindle at all. He's getting (or was getting, before the bearing "fell apart") .0005" runout on the inside of the spindle taper. While not exactly stellar, I suspect that's the best he can hope for with that machine. Seems unlikely that the taper would be bored cockeyed and yet that close to concentric at the big end.

I doubt that he has access to a precision test bar with the correct taper. The possibility that the shaft is not square in the collet can be eliminated by rotaing it in the collet. Same for the collet in the taper. At the very least, the test has the possibility of ruling out a bent spindle.

He says he was getting a good finish, so it seems to me that it's unlikely that the bearings have side play.

THMguy123
Posts: 7
Joined: Mon Mar 11, 2019 10:38 am

Re: Odd runout on mini lathe

Post by THMguy123 » Wed Mar 13, 2019 10:45 am

Yes, rollers fell from cage. I have two cage halves, and a pile of bearings. Hopefully that makes sense.

Appreciate the responses so far guys. I need to get another bearing before I can do much more.

John Hasler
Posts: 1271
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Odd runout on mini lathe

Post by John Hasler » Wed Mar 13, 2019 11:17 am

Can you tell us what type of bearing it is? Photos? IIRC I've seen some where nothing prevented the rollers from falling out of the cage when it was off the inner race. These can be re-assembled as long as none of the rollers made good its escape (stick them in with assembly lube).

Before assuming that the rear bearing is bad I'd try removing the driving gear and spinning the spindle by hand to see if you still get noise and vibration.

THMguy123
Posts: 7
Joined: Mon Mar 11, 2019 10:38 am

Re: Odd runout on mini lathe

Post by THMguy123 » Wed Mar 13, 2019 3:52 pm

I will post some pictures when I get home tonight.

Bearing ID number is 30206. I tried separating the other set of bearings and could not get them to come apart, so it would be my guess that these are not supposed to come apart.

The manufacturer is sending new ones, they were under the impression this is not supposed to happen either.

John Hasler
Posts: 1271
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Odd runout on mini lathe

Post by John Hasler » Wed Mar 13, 2019 7:04 pm

What the manufacturer says goes.

THMguy123
Posts: 7
Joined: Mon Mar 11, 2019 10:38 am

Re: Odd runout on mini lathe

Post by THMguy123 » Wed Mar 13, 2019 11:33 pm

Couple pics...waiting for the bearing separator to get here in the mail so I can get the other half off.

Image

Image

spro
Posts: 7640
Joined: Mon Feb 20, 2006 11:04 pm
Location: mid atlantic

Re: Odd runout on mini lathe

Post by spro » Thu Mar 14, 2019 2:43 am

Providing you get the the right size bearing separator, it should work well. The inner, knife edges may need to be trued up. The clamping will bring the inner race out only a bit. Reclamp and get a deeper bite but not able to touch the spindle. Apply shims as required to bring it further out from the spindle

THMguy123
Posts: 7
Joined: Mon Mar 11, 2019 10:38 am

Re: Odd runout on mini lathe

Post by THMguy123 » Mon Mar 18, 2019 12:13 pm

Got the new bearing in place. Checked run out on chuck side and I'm not seeing any movements on my 0.001" dial indicator. Opposite end is still running out of round, think I will leave it for now, until I have more time to diagnosis. Vibration seems to be less noticeable from before.

John Evans
Posts: 2031
Joined: Tue Jan 20, 2009 9:33 pm
Location: Phoenix ,AZ

Re: Odd runout on mini lathe

Post by John Evans » Mon Mar 18, 2019 10:45 pm

Those rollers are FRIED !! totally JUNK !
www.chaski.com

Harold_V
Posts: 17688
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Odd runout on mini lathe

Post by Harold_V » Tue Mar 19, 2019 1:03 am

I'm not sure what you're seeing in pronouncing the rollers as fried. While they shouldn't have been out of the cage, they appear, to me, to be fine. Otherwise the covering would most likely not be clear, free of color, and I suspect that the surface of the rollers wouldn't be bright and shiny. What am I missing?

H
Wise people talk because they have something to say. Fools talk because they have to say something.

Post Reply