[4]

How can I straighten a large cast pulley?

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

bpimm

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 21, 2012
Messages
285
My compressor just flipped another belt, the pulley on the compressor head has about .5" of wobble and I think that's what's causing the belt to give up, only happens every couple years but I thought it was time to see if I can fix it.

There is no ID tag on the compressor head but the name plate on the mounting plate says Kellog Model EM33-E. The shaft is strait, I put an indicator on it and turned it over by hand so the wobble is in the pulley. My original thought was to bore out the center and bush it back down to the shaft size but my lathe isn't big enough to grab it by the outside. the pulley outside diameter is 22.5". After getting the pulley off the compressor I'm not sure if I can do the bore and bush because the hub has a thin extension on it that might be compromised by the bore.

Any suggestions for straitening this thing out? I have a HF 12 ton press and a porta power to work with.
IMG_20190911_161534740.jpgIMG_20190911_161548016.jpg
 

Attachments

kvt

Active User
H-M Supporter - Gold Member ($25)
Joined
Oct 21, 2014
Messages
2,080
Yours is in better shape than mine, It also has a wobble and has for as long as I can remember, it is the same one that my dad had on his truck for fixing large tractor flats. don't remember it ever throwing a belt. Mine was built about 1966
 

pstemari

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
May 18, 2015
Messages
471
What sort of belt does that take? It doesn't look like a normal v-belt. Ordinarily, I would just suggest buying a new pulley, but I'm not sure where I look for one of those. Maybe SI-SDP?

Sent from my Pixel XL using Tapatalk
 

matthewsx

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Jan 2, 2019
Messages
516
Obviously you need a bigger lathe to do this job:grin:

Seriously though, if you can't resolve the issue with adjustment I would be reluctant to do anything. A part like that is under more strain than I would like to mess with, at the very least consult someone with real experience in the field before attempting anything.

JMHO....

John
 

bpimm

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 21, 2012
Messages
285
I think it is just a standard 5/8" v belt, just 4 of them. I've only been running 1.

Kvt the only date I can find is on the tank and it's 1936
 

fixit

Active User
H-M Supporter - Gold Member ($25)
Joined
Feb 8, 2014
Messages
279
If you put pressure on that pully to correct the wobble it will BREAK! I would mount it on a known true shaft to verify the crank is not bent, I have seen mang bent crankshafts. If it wobbles & the crankshaft is true then it's a machining problem & was that way from the get-go. How many belts do you run on it? There is paint in the belt grooves. Have you used a POLY BELT? Checked belt alignment?

Just saw you only run one belt, I would almost bet if you used 4 MATCHED belts or POLY-BELT problem would be solved. Just my 2 cents.
 

matthewsx

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Jan 2, 2019
Messages
516
They built it that way for a reason, try more belts.

It's unlikely the spec requires it to run very true, as long as it's driving the pump it's doing the job it was designed for.

John
 

MontanaLon

Active Member
Registered
Joined
Mar 15, 2019
Messages
233
When you say "wobble" do you mean axial or radial? Simple English is is moving side to side in line with the motor or is it moving in the direction of the belt travel?

The first could be a casting flaw that can't be corrected or it could be a misaligned bore which could be fixed. The second would be an off center bore which could be fixed.

My guess for why you are running it with one belt is that the pulley on the motor you have only has one track. It would actually be easier to make a replacement for that with 4 tracks and run it with 4 belts.
 

Chipper5783

Active User
H-M Supporter - Gold Member ($25)
Joined
Sep 25, 2014
Messages
781
Does the wheel appear to be damaged? How old is this machine? Perhaps it has been like that since day #1. Granted it would be nice if your drive belt didn't jump off from time to time - but I'd have a go at playing with the alignment, play with the tension, try a couple different types of belts. I agree it would be nice if the flywheel ran mostly true - but don't wreck it trying to fix what isn't really broken.

I have a 5HP compressor with a flywheel about that big - it has two grooves but it only had one belt on it when I bought it 18 years ago - it was far from new then (I'm still running the same belt it came with).
 

FOMOGO

Active User
H-M Platinum Supporter ($50)
Joined
Sep 2, 2013
Messages
2,026
I'm guessing it was knocked over or dropped while being moved, and was bent. Close inspection by mounting on a straight shaft (or just back on the pump if your sure the crank is true) with a pointer on the outside diameter would show where it's out. If it bent one way, I bet it would bend back with the proper setup. The approach Mr Whoopee pointed out would also be an option. Mike
 

cathead

CATWERKS LTD
Registered
Joined
Feb 7, 2013
Messages
1,099
The pulley was likely straight from the factory. FOMOGO's inspection idea is excellent! The blue paint is suspicious
for one thing as the compressor surely started life with multiple belts. If one of the fan blades were
cracked and repaired and painted it would likely have the aberration you are experiencing. Another thing, the first
photo looks like the pulley possibly has a sleeve in it. Could some previous owner have attempted to repair it ?

Putting hydraulic pressure on the pulley could break it so would proceed with caution. One final thought...If there
is any play when you just slide on the shaft, could you possibly install a thin shim in the right place to lessen the wobble
at least some? I would experiment with that first as it would be harmless to try.
 

bpimm

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 21, 2012
Messages
285
If you put pressure on that pully to correct the wobble it will BREAK! I would mount it on a known true shaft to verify the crank is not bent, I have seen mang bent crankshafts. If it wobbles & the crankshaft is true then it's a machining problem & was that way from the get-go. How many belts do you run on it? There is paint in the belt grooves. Have you used a POLY BELT? Checked belt alignment?

Just saw you only run one belt, I would almost bet if you used 4 MATCHED belts or POLY-BELT problem would be solved. Just my 2 cents.
Breakage is a concern, but if it bent one way will it bend back? probably not worth the risk.
I tried 2 belts, the motor has a 2 groove pulley but they were not a matched pair and the length difference was to much so I ran the shorter one until it gave up then ran the longer one and now it's given up. I bought a double belt to fix it but I must have measured wrong and it was to long so I tossed it aside and ran it the way it was. I'm in the process of changing the motor pulley to a larger size, should increase the compressor speed about 20%, it's only turning about 325 RPM now, the new pulley will get it up to about 400 RPM. I modified the mounting hardware so with the bigger pulley and more adjustment room the double belt should fit.

With 5HP compressors running single belts I figured that this would be ok with a single belt, it's a 5 HP motor, I don't know what the compressor head is rated for.
 

bpimm

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 21, 2012
Messages
285
That job needs to be done in a mill. Bore and braze a bushing in, then finish bore.
I thought about that but without a boring head... but this morning I remembered buying one for a project a while back and then not doing the project, guess I forgot I had a new one on the shelf, :bang head:

Now I would need advise on indicating in a 22.5 inch circle on the mill table, I don't think I have enough travel to use an edge finder, I'll need to make something to mount an indicator in the spindle that can reach out a foot.
 

bpimm

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 21, 2012
Messages
285
They built it that way for a reason, try more belts.

It's unlikely the spec requires it to run very true, as long as it's driving the pump it's doing the job it was designed for.

John
True, but it does cause some vibration/shake I'd like to get rid of if possible.
 

bpimm

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 21, 2012
Messages
285
When you say "wobble" do you mean axial or radial? Simple English is is moving side to side in line with the motor or is it moving in the direction of the belt travel?

The first could be a casting flaw that can't be corrected or it could be a misaligned bore which could be fixed. The second would be an off center bore which could be fixed.

My guess for why you are running it with one belt is that the pulley on the motor you have only has one track. It would actually be easier to make a replacement for that with 4 tracks and run it with 4 belts.
It's axial wobble, I guess it could have came like that but I assumed it got hit at some point in it's life and bent.

Pulley on the motor has 2 tracks, see previous answer fir full story of laziness...
 

bpimm

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 21, 2012
Messages
285
Does the wheel appear to be damaged? How old is this machine? Perhaps it has been like that since day #1. Granted it would be nice if your drive belt didn't jump off from time to time - but I'd have a go at playing with the alignment, play with the tension, try a couple different types of belts. I agree it would be nice if the flywheel ran mostly true - but don't wreck it trying to fix what isn't really broken.

I have a 5HP compressor with a flywheel about that big - it has two grooves but it only had one belt on it when I bought it 18 years ago - it was far from new then (I'm still running the same belt it came with).
I can't see any damage but it may become apparent when I clean the pulley, the only date I can find on the machine is on the tank cert plate and that is 1936. The compressor ID plate is attached to the mounting plate on the tank and the welds look factory so I think it's original.

That was my thought process that a 5HP compressor is good with 1 modern belt, maybe in 1936 the belts couldn't handle it.
 

bpimm

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 21, 2012
Messages
285
I'm guessing it was knocked over or dropped while being moved, and was bent. Close inspection by mounting on a straight shaft (or just back on the pump if your sure the crank is true) with a pointer on the outside diameter would show where it's out. If it bent one way, I bet it would bend back with the proper setup. The approach Mr Whoopee pointed out would also be an option. Mike
That's what I thought, it got bent. but now I'm concerned about breaking if I try to bend it back, Cast does like to break.

I need to put an indicator on it and see how it's bent, the crank measures good. I had a thought, clamp the wheel to the side of the press and then put a shaft in it and push on the shaft with the ram to tweek it back.
 

bpimm

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 21, 2012
Messages
285
The pulley was likely straight from the factory. FOMOGO's inspection idea is excellent! The blue paint is suspicious
for one thing as the compressor surely started life with multiple belts. If one of the fan blades were
cracked and repaired and painted it would likely have the aberration you are experiencing. Another thing, the first
photo looks like the pulley possibly has a sleeve in it. Could some previous owner have attempted to repair it ?

Putting hydraulic pressure on the pulley could break it so would proceed with caution. One final thought...If there
is any play when you just slide on the shaft, could you possibly install a thin shim in the right place to lessen the wobble
at least some? I would experiment with that first as it would be harmless to try.
The whole thing was painted blue when I got it, pretty good paint as it held up in the groove with a belt running in it.
I don't think that is a sleeve but I'll know more when I get it cleaned up.

It's tight on the shaft, I had to use a puller to get it off even with the clamp bolt out.
 

markba633csi

Platinum
Registered
Joined
Apr 30, 2015
Messages
4,180
If you have a full size mill like a Bridgeport and a lathe make a short arbor to help indicate the pulley on the table. Then bore it and sleeve. Lock it in with some super duper loctite or epoxy.
I wouldn't try to straighten cast iron even with heat.
Mark
 

projectnut

Brass
Registered
Joined
Apr 14, 2014
Messages
717
Before attempting to bore and bush the pulley do some more measuring on the compressor shaft and the bore of the pulley. It's likely the shaft isn't full diameter at the end, and the bore is oversize. I also have a Kellogg compressor that at one time had a similar wobble at the pulley. I researched boring and bushing, as well as using a taper lock. In the end all of those options were discarded because boring the pulley would have left the remaining sleeve without enough strength to remain true even when silver soldering in a bushing. I was afraid the cast part would crack when applying sufficient pressure to the cinch bolt to secure it to the shaft.

In the end I found the keyway on both the shaft and the pulley had worn to the point the pulley would not stay tight to the shaft. The resolution in my case was to true the keyway in both the pulley and on the shaft, then make a custom key, both longer and wider than the standard that came with it. I also used Loctite shaft retainer to hold the pulley tight to the shaft.

The pulley on my compressor has been tight and true for 5 years since the repair

If your shaft is worn to the point shaft retainer won't work Loctite also has a product called FixMaster for repairing wallowed out keyways and undersize shafts.
 

ericc

Active User
Registered
Joined
Dec 24, 2013
Messages
466
I did a similar thing as one of the suggestions above with a zamak pulley. Even with slow gentle bending, I ended up breaking it. I put it back into service by sandwiching it between two steel plates and torquing bolts in until it was straight and stable. It won't come apart, but you don't want to get caught in any protruding parts. Eventually, I guess I will replace it.
 

Nogoingback

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Oct 18, 2016
Messages
1,371
I think it is just a standard 5/8" v belt, just 4 of them. I've only been running 1.

Kvt the only date I can find is on the tank and it's 1936

It's not relevant to your pulley question, but if your tank was manufactured in 1936, you may want to give some thought
to it's safety due to rust:

 

NortonDommi

Brass
Registered
Joined
Nov 15, 2016
Messages
554
I'd check the shaft very carefully and the bore alignment. This could be done by laying a plate across the rim and fitting a shaft to the bore, a good square and a flashlight are all that is needed, If misaligned an easy way to fix is hire a Magdrll and get two cutters, one at nominal bore and another say 1/8" or whatever deemed suitable,(and don't discount Metrickery for getting odd sizes), larger. Use the nominal bore size to center and clean up bore then switch to the larger size. Drill and fit a sleeve with epoxy and cut the slit a couple of days later when the epoxy has set. Ream and fit. I'd work from the outer face.
The grooves and the faces of the rim are machined at the same time so the face will be square to the grooves .
 

nnam

Active Member
Registered
Joined
Jul 15, 2016
Messages
132
I like the suggestions about checking it out first. Check the shaft's diameter at various places and check it with an indicator to see if it's true. Mic it to check for the diameter and compare that with the pulley.

For the pulley, I would first just check against a flat surface, simply such as your granite table (not even precision table).

If the shaft is bad, then that would need to be trued up.

If the pulley is the problem, my suggestion would be to find yourself some fire bricks and heat this up to certain temperature and prepare to true it up some how (clamp, etc.).

But ..., what if the pulley is not bent, but its center axis is not the same as that of the outside? Maybe make a tight fit rod, insert it in and check it with a dial indicator as you rotate it? If it's bent, maybe heat it up, weld it then drill it out with a mill or bore it with a mill and put an adapter into it (better idea)

But the experts here probably have better hand on experience and advice
 

kvt

Active User
H-M Supporter - Gold Member ($25)
Joined
Oct 21, 2014
Messages
2,080
it seems yours seems even older than mine which means prob hard to find a good pully for it.
I agree that to much pressure could break it, would not try using the press on it.
To test it you could put it on a known good shaft supported by a bearing on each end and held some how. Then put an indicator on it You should be able to check both the hub area and the outer area. This will also allow you to get a true measure of how far out it is. and possibly what the problem is
Just my 2 cents
 

bpimm

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 21, 2012
Messages
285
it seems yours seems even older than mine which means prob hard to find a good pully for it.
I agree that to much pressure could break it, would not try using the press on it.
To test it you could put it on a known good shaft supported by a bearing on each end and held some how. Then put an indicator on it You should be able to check both the hub area and the outer area. This will also allow you to get a true measure of how far out it is. and possibly what the problem is
Just my 2 cents
Finding a new pulley is out of the question, I found 1 that might work and it was $1300.00.

I got some time this morning to work on it again and I cleaned the crank shaft and remeasured it, it runs true and the diameter is 1.375 +0 - .002

I laid the pulley on a flat surface and the rim is as true as my flat surface, Cast table saw top.

There was a lot of crud in the pulley hole so I cleaned it out good and remounted it on the compressor and the wobble went from .490" down to .150".

It fits nice and tight when it's clamped down but has a little play when the clamp bolt is loose, I'm thinking I will see if I can shim it to get it a little better unless that's a bad idea. I may just live with the .150".
 

Attachments

bpimm

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 21, 2012
Messages
285
When I put the pulley back on the compressor it seemed to require to much torque on the clamp bolt to get it to quit having play so I took it off and set it up on the mill table and ran an indicator down the hole and the side was +- .010" so I put a snap gauge in it and the hole has .009" of taper, open on the side to the compressor.

My thought is it needs to be trued up, it takes more than 100 Ft Lbs to tighten the clamp bolt enough to stabilize the pulley, using my highly calibrated hand wrenches on a movable object, lol. I can't get a torque wrench on it but it's everything I can get by hand.

How thin of a sleeve can I get away with if I bore it true then epoxy the sleeve in then rebore the sleeve to size?

Also if I do this would I bore to final size with the clamp bolt out, clamped down or somewhere in the middle?

Thanks.
 

matthewsx

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Jan 2, 2019
Messages
516
Seems like you're on the right path. Have you considered some thin lead sheet, or maybe the ubiquitous beer can shim. My inclination is still to leave the pulley as-is if you can, anything you do to fix it that's permanent might introduce other problems that are worse. Remember, as much as it might bother you to see it wobbling around if it makes compressed air it IS doing the job it's intended for.

John
 
[5] [7]
Top