When To Say Bushing Needs Replacing??

Hello Carroll :)

As Bob Korves suggested, are you measuring the shaft at the very end where it goes into the bushing? That's where the measurement counts. Anywhere else along the shaft doesn't matter, as that wear would be a result of the apron feeding along the shaft.

You probably already realize all of this, but just checking... :)

Brian
 
Yes sir I did,and took a closer look at the bushings.Looks like there were ran dry for a while,so going to go ahead and replace them.And order some 90*angle oil cups.Oh well its just a minor setback but its for the good.
 
Bushings rarely wear evenly (round) or concentric. A careful measurement across the bore at various points should indicate an eccentricity that will give you a better idea of the original tolerance. The feed-screw will probably work just fine with .006 clearance in the bearing but it will not hold oil very well between the parts. Rather than use heavier oil I'd opt to change the bushing.
 
Guys wanted to run my bushing replacement game plan by ya"ll to see if I am on the right track.Looking at the pic the long bushing is the original for the lead screw.The small ones is what I plan to go with as the replacement.I was thinking that pressing these in on both ends of the opening will leave a 1/4 gap in between the two bushings.Next I'm going to cut some felt and line that gap with it so that it will wick oil all the way around.Guys the old long bushing was really bad looking on the inside.So I though that maybe the felt would keep the bushing and shaft wet.Looking at couple manuals one manual show just one long bushing then look at another and it shows two small bushings.Does this sound like a go?Weekend is coming up,thanks guys
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I have seen two bushings with a gap. I have seen a bushing with a groove milled around the oil hole. I have seen what look like screw threads inside bushing to drive oil in deeper.
Never seen a piece of felt actually between the bushings, but I have seen felt used to carry oil to the bush.
My instinct tells me it is not a good idea. Could be wrong (I probably am). I think the felt will trap particles and act like a nice source of lapping material...
 
joshua43214 said:
I have seen two bushings with a gap. I have seen a bushing with a groove milled around the oil hole. I have seen what look like screw threads inside bushing to drive oil in deeper.
Never seen a piece of felt actually between the bushings, but I have seen felt used to carry oil to the bush.
My instinct tells me it is not a good idea. Could be wrong (I probably am). I think the felt will trap particles and act like a nice source of lapping material...
Click to expand...
Trapping grit was my first thought also when I was picturing the setup with the felt in place. I would think that just leaving a 1/4 gap between the bushings where the oil cup is going to feed will keep a good supply of oil in place for the bushings (maybe to much which will cause a mess as it leaks past the shaft).
 
Since the shaft doesn't slide to and fro, only rotates, I don't see how the felt would accumulate grit on the shaft side. In fact, it would act as a filter to any grit introduced into the oil cup; which is why you see felts or sintered metal filters in oil passages from time to time. I have ball type git oilers on mine. I'm not sure that's any cleaner. Either way, I don't know if the felt offers much advantage in supplying oil as gravity and capillary action will determine the supply. In fact, a large oil reserve above the bearing will likely assure some level of drip, drip, drip until the reserve runs out. A well fitted bushing should hold a sufficient film of oil for quite some time after that. I suspect the felt is fairly moot but I do like the filter aspect.
 
If you haven't already removed the old bushing you can slit it with a hacksaw blade to aid in removal and freeze the new ones before installation. Some come out easy, some not so much, depending on the press fit. Mike
 
What Kroll is doing putting two bushings in the housing at each end is the same arrangement that is on my Sheldon lathe lead screw support. Works good for the 32 something years its been in place. I give it some oil every now and then, as long as you can see a bead of oil around the shaft at the bushing, it's getting oil. I didn't put any felt in the void on mine. Don't really see a need for it. Ken
 
I wouldn't put any more than a .0005" interference between the housing and the bushing. Any more than that and you'll be reaming out the bore to get the shaft to go in.
 
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