Spindle Binding When Trying To Bring Tolerance Into Spec.

take it to a auto rebuild shop and have the spindle od lapped, put it back in the housing and adjust the spindle lift using plastic shim and a torque wrench . Set the lift to around .001-.0015 lift after it is warm. Don't remove any more stock than necessary, all the line don't have to be removed.
 
I think the blacksmith in me would do a reverse scrap-in. Using vee blocks, I'd mark out the "high" points on each journal and remove material at those diminishing spots until I could detect as little as possible TIR. Pick your vee block locations well, and never move them. Then to the polishing phase and get the rest blended and smooth as possible. If the spindle is bent between those two journals, so what? We're talking about a minuscule amount of material to be removed anyway, so if the middle areas stay out, it's no big deal. It's basically the same things as scraping in a pair of ID journals using a known straight pin to highlight the to-be-removed material. Done it after weldup on truck differentials a few times and it seemed to be fine even with the load they carry.

Use your imagination.
 
No the bearing caps do not heat up. It is all reinstalled now, I think I will run it this way for a time to let the original spindle "run back in" to the headstock. I will take my suspect spindle to a machinist friend to do a more accurate measurement of true. thanks all for your remarks. These issues are not the kind of answers you find in books or youtube.
 
Tony, thank you for the information. unfortunately I do not have the knowledge, tools or even understanding to implement your direction. I am a rank novice and I am learning on my own. I have reread your info and I will do some research to understand things like scraping in a ID journal. Thanks.
 
If you were in my neighborhood, I'd be happy to help with it, but as I recall, we're far apart. What I am describing would require a little finesse, but not a lot. Just think about what I said, take it one step at a time. All you would be doing, in essence, is removing the high spots from the effect of the bend, the center of which you don't know and don't care for what I am describing.

If you were willing and able to spend a bit on it, you could have the bearing journals sprayed up and reground dead true to each other, and really, that's all that counts for this. After getting the spindle true, of course, the register surface of the chuck and faceplate mount should be skimmed back square with the "new" axis. If the spindle is bent, then that surface must also be out of true.

Maybe someone near you could come to your aid.
 
Open question. given that my original spindle is scored and galled, given that the casting in the headstock has to be scored and galled as well. Does it make any sense to buy a smooth spindle in good shape and install it int he headstock and simply adjust the shims. Can the tool perform better with a good spindle in a less than good headstock?
 
No like i stated before, take it to a automotive engine rebuilder shop and od hone the spindle, put it back together and re shim, adjust the bearings to +.001-.0015. After that run some thin synthetic oil like 5- 20, it should work fine it is only a lathe not a precision grinder. I used to rebuild high speed spindles,and this is a cheap fix. If you knew how to scrap i would scrap in the housing, but don't attempt it if you never scraped in bearings before. ( only remove min amount of od stock, don't go for removing all the lines)
 
I am sorry I may not have stated my question correctly. I can buy a replacement spindle for under $100 that is without scoring or galling. My question has more to do with making such an investment given that the condition of the headstock is poor as evidenced by the original spindle. I am thinking that the cost to refinish will be equal to or more than a replacement and either way it will go into a headstock bearing surface that is less than ideal. Is it all worth it? will it matter to basic operation?
 
Thanks, I take it to mean a clean shaft or the scored shaft will perform the same since the mating surface has not been improved. One last question before I resign my self to the Lathe's working condition. If I took my diamond dressing tool, a flat bar type for dressing grinding stones and I mounted it in my QCTP and ran it up to the tail end of the spindle and kissed it like you do with chalk to check for concentrically. Would that "grind" of a few thou on the high spot and bring that end closer to concentric? I figure I have nothing to loose with a crude "haircut" if it would even work.
 
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