The 3 jaw chuck on my lathe is the original chuck, (73 years old). It was beat up badly over the years and looked bad, but still works. Depending on the grip diameter, the runout was between .004" and .010". Due to the fact I cannot afford a new chuck, I decided to repair this one. It looked so beat up, I disassembled it, cleaned everything and put the shell back together. I then turned .020" of the chuck body diameter to clean it up. The pinion gears that are turned by the chuck wrench were really beat up badly so I chucked them in an ER 40 collet and cut .040" off the face to make them pretty. Next I cleaned everything and reassembled the chuck using white lithium grease on all the gear faces.
Now the chuck looks almost new and the next trick is to make it a set true chuck.
This photo shows the steel ring I turned to bolt to the outside of the chuck body.
This photo shoes the chuck body and pinions machined an the ring bolted on. You can see one of the 4 1/4-20 set screws to align the chuck.
The backplate has the register machined undersized and the bolt holes are over sized to allow .020" movement in any direction.
It may not be as great as a new chuck, but it is pretty darned good.
The only thing left to do is to counter sink the bolts for the ring for head stock clearance.
Now the chuck looks almost new and the next trick is to make it a set true chuck.
This photo shows the steel ring I turned to bolt to the outside of the chuck body.
This photo shoes the chuck body and pinions machined an the ring bolted on. You can see one of the 4 1/4-20 set screws to align the chuck.
The backplate has the register machined undersized and the bolt holes are over sized to allow .020" movement in any direction.
It may not be as great as a new chuck, but it is pretty darned good.
The only thing left to do is to counter sink the bolts for the ring for head stock clearance.
