When To Say Bushing Needs Replacing??

Thanks guys for all the feedback,the felt is out.But the bushing is going to be a snug fit and I don't want to do any reaming.I think these are about .005 over so to help to install them,how long do I need to leave these in the freezer?
 
Probably an hour would do it. I normally leave them overnight, but I don't think it's really necessary. Mike
 
Thanks guys will be giving it a try today
 
It went very well,they were still kinda tight but pulling them out of the freezer they were .003 smaller.Just finish bout hr ago,so tomorrow put little oil on them and slide the leadscrew and power feed shafts in.
I think that the freezer ideal is the secret to todays success,thanks guys----kroll
 
I like the twin bush idea, and the felt idea. It would hold oil for a slower release, preventing a complete lack of oil if ever neglected.
Any foreign matter getting to the felt would be there anyways.
 
Thanks,while the members here are asleep,I may just go ahead and put the felt in.When I done a SouthBend it had felt all over the QCGB and running through the apron.Don't tell anyone----kroll
 
There is felt in zillions of small electric motors that have bronze bushings and are lubed one time only.
 
Bushings.............The replacement bushings you have look like oil lite. Which is a bushing formed by compressing splinter bronze. Oil lite is porous and as the bushing heats up the pore expand and oil is drawn to the friction point. You could put 3 bushings in with no space between, and still use the oil cup and the repair would last a life time. As a mater of fact, I have cabinets of bushings (I am a starter rebuilder) and I am sure that I have some bushings that would be a good fit for what your doing. .003 is a good press fit. Bushing to shaft clearance .0015 to .003 is a good running clearance. The amount of shrinkage is actually the volume of material that is displaced on the outside, as the bushing shrinks, added to the inside. So it can be mathematically figured if you really want to. But you can also gestimate. If the press is .003 on a 3/4 bushing your going to get shrinkage of about .0035. If you start with a bushing that is .004 to .005 too large on the OD you should be right in the ball park on the press. They say not to machine oil lite bushings but I do on a fairly regular basis. It is said that it plugs up the holes inhibiting oil flow. If machining is necessary, try to pick a bushing that is right size ID and machine OD using a mandrel. I have more thoughts but don't want to be too wordy.............Tim
 
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