Clausing 5428 rebuild

[AndySomogyi]

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

 

[AndySomogyi]

I managed to diagnose the source of the spindle noise down to extremely worn bushings in the main drive pulley.

After going through a long deductive process of eliminating every other possibility, this is the only source of noise that remained. I replaced all the idler bearings, and verified the main spindle bearings are acceptable. The spindle did spin free, and made no noise with the bull gear direct drive pin disengaged. It only made noise with the direct drive pin engaged.

The explanation of the noise is pretty complicated, I tried to draw a pic, but I really need to make an animation. The deal is the bushing are worn oversize, and are almost certainly an eccentric. The belt applies a constant torque to the pulley. But the pulley applies a torque to the spindle through the bull gear pin. The direction of this torque changes as the spindle / pulley assembly rotates. So, sometimes the belt will want to lift the pulley up, and sometimes it will want to drag it down, depends on the angle of the pin. It’s this changing torque that hammers the pulley back and forth. With the pin disengaged, the torque is constant, so you don‘t get the hammering. The main idea is that with this kind of drive pin, you do need a surprisingly tight bushings.

Hopefully this information will help others diagnose their spindle noise issues.

The last two pics here are the actual bushings. Some previous owner rammed one of the bushings in all the way, thus blocking the oil hole.

Because I don’t have access to another lathe (even though there’s a complete unused machine shop down the hall from my office, the university bureaucracy makes it off limits), anyways, I have to use this lathe to make parts for itself. So, as a temporary hack, I packed the pulley bushings full of high pressure grease. I made a quick adaptor, drilled a hole in a 1/4-20 screw (thread of the oil hole), soldered a pipe to it, with a grease zerk. Then packed the crap out of these bushings with grease.

Sure enough, it quieted the lathe down significantly.

I also replaced the motor drive belt with a new one, with the belt change, at least the lathe no longer feels like a rodeo bull.

With the lathe hacked together enough now, I‘m going to make an arbor to hold bushings as I turn them.

I can verify that this drive belt fits correctly, there are two different styles of Clausing underdrive configurations, and both take this size belt:

Lower variable speed belt
Clausing number- 051-022
Original- RVS 505 09
Replacement- 1626V262

 

[AndySomogyi]

Got the lathe together enough to use it to make parts for itself. Got the bushing material to make new bushes, and Made an expanding arbor to secure the bushings when I turn the OD.

This has a 15° taper, with a steel anvil. I screwed up the arbor OD and made it 0.001 undersize, but it expands so I guess that’s OK.

Secured the bushes with an aluminum sleeve.

But unfortunately I screwed one of the bush IDs, the cross slide screw is super worn out and really hard to do accurate work with it.

Oh well, I’m $17, ordered another blank.

 

[AndySomogyi]

Got the bushings made, well made one extra because of the size bronze I got.

The expanding arbor work perfectly, managed to get them all within 2-3 tenths dimension wise, and about a tenth roundness wise.

The cross slide nut is really badly worn. I recorded exactly how much each 0.020 movement of the cross slide took off, and it’s all over the place. Only way I managed any accuracy is getting semi-close with the cross slide, then using the top slide at a 30° angle (sin(30°) = 0.5), so moved by half in the X.

Now, I need to pull the headstock apart again and install these bushings.

 

[mattthemuppet2]

looks like you're doing a cracking job! I had a similar issue with the spindle pulley on my Atlas 618 - first the bushings were worn and then when I replaced them I managed to ream them slightly on the tilt. Only properly fixed the problem when I made a new spindle pulley/ sheave.

 

[AndySomogyi]

Thanks! The Atlas and Clausing are a similar design (same company), I’m sure hoping my pulley’s OK. I had a friend say his was 0.003 oversize on the ID, hope I don’t run into that issue.

 

[AndySomogyi]

I did learn something about working with a badly worn cross slide, is that if you back it out and run it back in, it’s impossible to find the same position. Because there’s so much wear on the nut, it never returns to the same spot when you screw it back in. So I found it’s better to just turn the lathe off and drag it back. Yes, it does leave a scratch, but it’s the only way I found to maintain accuracy.

 

[AndySomogyi]

This would partially explain excessive cross slide slip, shim was doubled over.

 

[AndySomogyi]

Used the old and busted lathe to make parts for itself.

• Back-gear bushings made
• race and bearing pulling and alignment bushings made
• new spindle bearings here

Let’s tear this down and rebuild this spindle.

If I messed up the dimensions of any of these parts, guess I’m pretty much screwed, because I don’t have another lathe and don’t have access to one. If these parts are wrong, I’ve got a big pile of scrap iron.

 

[rwm]

Naw... we would help.
Robert