Lathe spindle noise, possibly backgear

[AndySomogyi]

Hoping some of you guys might help diagnose the spindle noise here. This is a Clausing, but Atlas, Logan, and probably many others use the same back gear design.

There is a very loud, persistent noise coming from the spindle with the bull gear engaged (direct drive), but no noise in back gear, or free wheeling.

Just cleaned, inspected and re-assembled the spindle assemble, same noise as when I first got the lathe.

The main bearings seemed OK by hand, and there was no marring on the races, races looked almost perfect. There is some wear in the back gear bushings, and I plan on making new ones.

I’ve tried adjusting different pre-load and no difference, right now pre-load is adjusted according to manual spec, in the spindle spins freely for about 1 revolution. Tried adjusting the collar that presses the drive pulls against the spindle with no difference.

If you turn the spindle by hand, in direct drive, and keep your hand on the main drive pulley, you can feel a slight rocking about once per revolution. This would seem to indicate that the bushings are damaged worse that I thought, possibly worn in an eccentric. So could a slight rocking of the main drive pulley be responsible for such noise?

I’m at a loss, because this noise does not sound like any bearing noise I’m familiar with.

In any case, I bought material to make new bushings. Do you suppose that with this noise, the lathe is good enough to make bushings on it (I don‘t have access to another lathe, have to use this one to make parts to fix itself).

 

[DavidR8]

It sounds remarkably similar to rod knock in an engine.
Maybe put a dial test indicator on the spindle bore and see what happens when you feel the rocking?

 

[AndySomogyi]

It sounds remarkably similar to rod knock in an engine.
Maybe put a dial test indicator on the spindle bore and see what happens when you feel the rocking?

Sometimes it’s a visible rock, I’d say maybe 0.020, maybe 0.030.

When I had it apart, the bushings looked like this, with one pushed all the way in, blocking the oil hole. I drilled out the oil hole, just to get it working enough to make new bushings.

 

[markba633csi]

Yep those pulley bushings are worn. Check Bunting bushings catalog, they are probably a standard size. I did this job on my Atlas/Sears 12" machine and reduced the play from about 0.004" to less than 0.0005" for about 12$ from Zoro- thankfully I have a second lathe which was needed to lap the inner bushing to match the spindle OD since the bushing was slightly undersize as received

 

[AndySomogyi]

They’re not a standard size, but I got original prints from Clausing for the exact size, and I’ve picked up the bushing material off eBay.

I’m just hoping using the lathe as it is, with the sloppy bushings does not damage the spindle. Sadly, this is the only lathe I have access to, so I have to use the lathe to make parts for itself

Also notice how one of the original bushings is pushed all the way against the other one, on the gear side. Well, the drive belts are on the section without a busing, so this is causing it to rock even more. This could be why it’s so loud.

 

[middle.road]

.020"-.030" 'rock'?
With a piece chucked up and a cheapo indicator, how bad is the runout?
With the backgear engaged I wonder if the runout is low enough to be able to make the replacement bushings?

With that kind of slop, concentricity might be difficult to attain.

Option #1 - I think that there are a couple of other members here from the Indy area. Perhaps they could lend a hand

Option #2 - Perhaps a Bearing shop in the Indy area still has a machine shop and they could make them up for you.

Option #3 - Custom RFQ from OilLite? Hate to think what they might charge though.

 

[AndySomogyi]

.020"-.030" 'rock'?
With a piece chucked up and a cheapo indicator, how bad is the runout?
With the backgear engaged I wonder if the runout is low enough to be able to make the replacement bushings?

With that kind of slop, concentricity might be difficult to attain.

Option #1 - I think that there are a couple of other members here from the Indy area. Perhaps they could lend a hand

Option #2 - Perhaps a Bearing shop in the Indy area still has a machine shop and they could make them up for you.

Option #3 - Custom RFQ from OilLite? Hate to think what they might charge though.

The spindle runout itself is about 1 - 2 tenths. The spindle shaft itself is solid, the pulley just slides over the outside of it. In direct drive, the pulley is locked to the spindle, I'm thinking it's just rocking back and forth. One idea is to try and pack the journal area with grease, i.e. squeeze grease into the oil hole (that's now open).

I've thought about using back gear, but I think that would cause more damage, because there the worn journal is actually riding over the spindle, wearing the spindle journal, whereas in direct drive, it's just thumping the spindle.

Another option that I just though of is to maybe drive a chunk of aluminum into the oiling hole, and press this tight against the spindle with a set screw. This should lock the pulley agains the spindle and not allow it to rock. Sure, it won't be concentric, but the belts are flexible and should allow some amount of pulley eccentricity.

 

[middle.road]

The spindle runout itself is about 1 - 2 tenths. The spindle shaft itself is solid, the pulley just slides over the outside of it. In direct drive, the pulley is locked to the spindle, I'm thinking it's just rocking back and forth. One idea is to try and pack the journal area with grease, i.e. squeeze grease into the oil hole (that's now open).

I've thought about using back gear, but I think that would cause more damage, because there the worn journal is actually riding over the spindle, wearing the spindle journal, whereas in direct drive, it's just thumping the spindle.

Another option that I just though of is to maybe drive a chunk of aluminum into the oiling hole, and press this tight against the spindle with a set screw. This should lock the pulley agains the spindle and not allow it to rock. Sure, it won't be concentric, but the belts are flexible and should allow some amount of pulley eccentricity.

I don't think I'd had enough coffee before posting.
So these bushings are in the belt pulley and not the spindle...
If you're looking at only a couple of tenths at the nose, you should be able to get the new bushings made.
Pack it with some high pressure grease and run with that.
I'd stay away from the aluminum, might gall really bad against the shaft and cause you other headaches.
Possibly slip some brass shim stock into the pulley bore? maybe, perhaps?

 

[AndySomogyi]

I don't think I'd had enough coffee before posting.
So these bushings are in the belt pulley and not the spindle...
If you're looking at only a couple of tenths at the nose, you should be able to get the new bushings made.
Pack it with some high pressure grease and run with that.
I'd stay away from the aluminum, might gall really bad against the shaft and cause you other headaches.
Possibly slip some brass shim stock into the pulley bore? maybe, perhaps?

Yup, bushings def in the belt pulley, same design as a South Bend, Logan, Atlas... The spindle itself is on tapered rollers.

I was thinking the same thing with high pressure grease, thanks man.

 

[AndySomogyi]

It’s definitely the bushings. I’ve made a temporary fix, just enough the use the lathe to make new bushings.

here’s a more detailed analysis

Clausing 5428 rebuild

That's great. I would try some isolation mounts on the cat also! Robert That’s Ike the cat. He’s my little buddy, friendliest cat ever, and yeah, he can be noisy, but we love him. Sent from my iPad using Tapatalk Pro

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