I see my name was mentioned earlier. Thank gosh you guys didn't use it in vain!
I do have a Logan 200, and I will get a couple of spindle photos and measurements for you later today if you wish. Just let me know.
Everything that everyone has said so far appears to be correct. You want to address any spindle runout issues before you attempt to correct any registration issues on your chucks or faceplates. Runout of .001" on the spindle seems like an awful lot to me, though I do not know what the factory spec was off the top of my head. Logan lathes were not Monarchs, Hardinges or LeBlonds, but I would still expect smaller numbers than what you are seeing on the spindle. It also appears to me that the runout on the registration boss was less than the runout on the inside of the taper which is a red flag for me. They should be very close to the same and should be concentric, in other words they should both be off the same amount at the same point in rotation of the spindle. From my experience, differences in the two often occur due to nicks or burrs on the internal taper. For some reason people are often not very careful about their treatment of those internal tapers.
Richard also mentioned warming up the bearings before taking any measurements, as this tightens things up and will give you more accurate readings of what is actually happening with your lathe.
Once you are satisfied with your spindle runout, you can then do something with the registration cuts on your chucks and faceplates, which are obviously not correct for that lathe. The reason that you need to address the spindle issue first is because any work that you do to the faceplates or chuck backplates is dependent on the runout that your spindle has currently.
Here is how I would approach your issue:
- Get a .0005 or a .0001 test indicator
- Recheck your spindle runout after allowing your lathe to run for a while and getting everything up to operating temperature.
- Examine the internal taper of the spindle very closely for any nicks, burrs, or other high spots. Any high spots can be removed with a fine stone.
- If the spindle runout is significant, beyond what you feel is appropriate, address that problem first. I would be looking for .0001" or less at the spindle.
- Properly bore the registers in your faceplates and chuck backplates.
- Remount your chucks on the backplates.
Don't expect used chucks to get you down to little or no runout. As scroll chucks (3 jaw) wear, their ability to center the jaw accurately decreases. You will also find that their runout will be different with test bars of different diameters. I have a newer Shars 6" 3 jaw chuck for mine, and I get .0003" runout on a 1" test bar mounted in the chuck. Very good in my opinion, but I think I just got lucky when cutting the registrations on my backing plate.
One last thing to keep in mind: the generally accepted practice when fitting a different chuck to a lathe is to replace the back plate so that new registrations are cut to fit that lathe. The chuck is then mounted to the back plate as machined for that lathe.