How To Repair Bushings & Pulley Bores

JPMacG

JPMacG

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I had to remove the 3/4 inch countershaft on my Craftsman lathe. This turned out to be no easy job.

I now have a pulley with a scored bore. I also have scored brass bushings on the countershaft support bracket. This happened as I pressed the shaft out of the pulley and bushings. The shaft had a lump from the set screws that held on the pulley and collar.

How can I clean up the pulley bore and bushings? Do 3/4 inch hones exist? Should I use a 3/4 inch reamer? Should I try emery paper wrapped on a wooden dowel?
 
If it's light scoring, just make sure there are no burrs and reassemble. If it's scored to the point of being loose on the shaft, you must enlarge the hole then turn a sleeve and press fit and/or locktite it in place. This sleeve will have a bore the same size as your shaft and the same outside diameter as the enlarged hole in the pulley.

Make sure you remove that setscrew mark on the shaft, and maybe even file a small flat where the setscrew rests to prevent raised marks in the future. Help the next guy along.
 
+1 what Andre said
But if the bushings are scored or worn to the point of concern I'd just replace them. You can polish off the shaft (an add the flat where the set screw rests), press in new bushings and reassemble. If you caught the issue in time and the bushings are not worn so much that the shaft is lose you should be in good shape.
You must have noticed a problem in the first place to want to remove the shaft so you might be in the same boat I am. I need to replace the two bushings and make a new shaft...No big deal really if you have the capabilities to cut the key-ways for the woodruff keys.
 
All of the bushings that I have replaced on my 12" Crafstman lathe have been standard off the self bushings available at most hardware stores. Just press the old ones out and then the new ones in. I have then used a sharp reamer to size.
 
Rob, Do you ream the new bushing by hand? Or do you fixture the part and ream it on a machine?
 
Thanks everyone. Now that I have cleaned the parts, the damage does not appear to be as bad as I first thought. I may be able to deburr the shaft with a file and fit it all back together. I will definitely add a flat for the set screw.

But on careful inspection I notice that the oil ports on the bushings don't go anywhere - there is no hole into the bushing. Shouldn't there be a small hole from the oil fitting into the bushing? I wonder if a previous owner has already replaced the bushings but didn't add the hole.
 
Most people seem to make the assumption that the oil cup hole should line up with a hole through the bushings. But all of the bushings that Atlas used (except maybe those where grease cups are present) are of the sintered bronze type commonly know as "oilite". The bushings themselves are porous and don't need a hole added to let the oil through.
 
Ahhh.... clever. Thank you Robert.
 
I have a question about Oilite type bushings. I've only ever seen them fitted by interference along their OD, so that they don't move with respect to whatever they are inserted into. Is is possible instead to press fit them and perhaps even loctite them onto the shaft at their ID, so that the bearing surface is the outside sUrface (OD) of the Oilite bushing? Why not?


Steve Shannon, P.E.
 
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