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Bearing failure.

Started by Grower, October 27, 2011, 07:07:52 PM

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Grower

Gidday, for the second time we have a bearing failure on the driven shaft on our mill, the last one started chewing through the shaft which was replaced along with 2 new bearings now its started doing it again, a slight squeak as it comes to a halt. How can I fix this problem? The engineer who made the shafts told me the bearing cant be lined up properly however all appears to be in order.
Its better to have it and not need it than to need it and not have it.

dutchman

What size is your shaft?   length, dia.?
What material is the shaft made of?
Are you using pillow block bearings?
Are you using radial pillow block bearings?

Shafts I made for TH30 are:
1.5 in dia.,14" long, 2 radial bearings are split off center.
The shaft it A2 steel.
I'm a part time sawywer, the last shaft lasted 9 yrs.

Grower

They are pillow block bearings, shaft size is 1 1/2" diameter and approx 12" long. No idea as to the type of steel shafting the engineers in town use it by the mile so to speak. The driving shaft gives no trouble at all and it has the two pulleys on it one for the triple B drive belt. Im heading out now to take a closer look at things.
Its better to have it and not need it than to need it and not have it.

timbuck2

Did you try the old piano wire (or fishing line) test, for run out?   Or maybe a guage if you really have it all together?

Grower

I have just taken the shaft out and its showing signs of wear after 2 hours. I have changed dozens of bearings in my time but have never had this happen. Back to the engineers now. I have posted a picture in my album of it, copper paste was used when it all went together to make things slide off when they need to come off.  >:(
Its better to have it and not need it than to need it and not have it.

Grower

Just home from town now, I took the shaft to a bearing dealer, they had no idea as to the problem but then I took it to a different engineer in town and the first thing he did was mic it up, its 3 thou undersize, hes going to get his teeth into it next week and do it properly, the way it should have been done the first time by the first bloke. Another set of new bearings coming up, I know who should be made to pay for the damage.................. >:(
Its better to have it and not need it than to need it and not have it.

Grower

 

  I think Im getting the hang of this copying and pasting in here, if you see a picture of that shaft, then its working........
Its better to have it and not need it than to need it and not have it.

dutchman

Grower, if your bearings lock on the shaft with set keys,
you can put a flat there to insure set key locks bearing in place.
If you need to set the shaft in place to get proper location for bearings,
you can mark set key location ( with marker ) then drill shaft so set key
sits in hole.
My shaft only has @ 1/2 thou. clearance, but I hand fit shaft to bearings.
I'm a tool and die finisher, fitting parts is what I do.

beenthere

Quote from: Grower on October 28, 2011, 03:45:24 AM
  I think Im getting the hang of this copying and pasting in here, if you see a picture of that shaft, then its working........

You can always tell if "its working" by clicking on the "preview" button before posting. It works every time.

Good on the pics.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

eastberkshirecustoms

You should be using 1045 TG&P cold rolled round bar (Turned, Ground & Polished) for you shafting. It is stronger and more precise than 'regular' 1018 cold rolled, which has a tendency to be a few thousandths undersize. Because of the tighter fit, you may need to freeze the shaft overnight to assemble it. The other option would be to heat the bearings (which I personally don't like to do) and requires an expensive induction bearing heater to do properly.
1045 TG&P costs more, but should take care of your shaft failures. On a side note, is your mill a 'home brew'? I think that upsizing your shaft size may help you to take flex and vibration out of the equation. My drive side is 2-11/16" and idle side is 2".

Grower

Well thanks for all the advice eastberkshirecustoms and everyone else. The wheels have been balanced. The engineer (not the same one who knocked that shaft up) is going to make a whole new setup with different bearings, the whole 9 yards. They are going to turn a new shaft down to size with a different type of bearing as well. All I have to do is unbolt it and take the shaft, bearings, blocks and pulley in to them next week. Both shafts are 1 1/2" and the driver which of course has 2 pulley's on it has never given any trouble. Other than that shes been cutting pretty well. We were civilising some eucalyptus from out the back of the place, it looked like red ironbark after it was cut but now we don't know what it is, just waiting for them to flower and take the flowers, some pods and leaves to town for ID, heavy as lead and she cut straight through them!!!!!!
Its better to have it and not need it than to need it and not have it.

Old Iron nut

   Grower, you may have to go with a fixed bearing as well as an expansion type bearing on that shaft. Use the fixed bearing closest to the part you do not want moving endwise (bandwheel), and the expansion bearing on the belt pulley end. Hope this helps your problem.

Grower

Yea I think that's what they were talking about doing old iron nut. Sounds like she's all under control now.  ;D
Its better to have it and not need it than to need it and not have it.

Grower

The engineer told me to try using Loctite 641 in the meantime, which we did. You have to smear it on the shaft before before you reinstall the bearing etc. Surprise surprise its doing the trick, apparently it sets like concrete on the shaft and fills the gap. No squeaking, nothing and the mill is up and running. I was told to let it set for 24 hours before use. the also told me it may last a month or the life of the bearing.  ;D
Its better to have it and not need it than to need it and not have it.

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