The mill is rough turned to 2 3/8 inch diameter. I drilled the hole for the body first, then parted the top and drilled the top for the shaft. When I put the top tenon into the bottom hole there is no play but the tenon top is not concentric with the bottom hole.

Is it possible to fix this?

  • 3
    Maybe show a picture or a drawing?
    – jdv
    May 29 '20 at 1:10
  • Hi and welcome. I'm not sure if we can properly diagnose the problem without a diagram — how does this nonconcentricity show itself? But the simplest fix is just to start again. Attempting, and succeeding in, doing the repair/fix may be a useful learning experience but you won't get what you originally planned anyway. So beginning again is really the best thing to do at this point I'd have thought.
    – Graphus
    May 30 '20 at 5:47
  • Specifically, I'm having hard time understanding how you cut the center and the body differently. Wouldn't you cut the profile, then ream the hole concentric with that without changing the setup, before parting the two pieces? This leaves two pieces with matching concentric holes and profiles. that is, it isn't impossible to have these dimensions match with separate setups, but it will not be easy. And you would need a very accurate reference face for any setups.
    – jdv
    May 30 '20 at 15:57
  • The solution is just hold the top part by the tenon and turn it ro round. Then there is no problem.
    – Ron
    Jun 5 '20 at 15:37

Is it possible to fix this?

  • Put the top into the base
  • chuck it firmly into the lathe
  • turn the top so it's now concentric

I'm not sure that this is be recommended, however. I believe it's extremely likely that the two pieces would separate while spinning on the lathe and that would be a Bad Thing™, potentially causing injury and/or damage.

It should be, however, possible.

  • Your suggestion is what I tried first, but it did not work. Both top and bottom got to a smaller diameter, but they are still not concentric Ron
    – Ron
    May 29 '20 at 17:36
  • 1
    I can't see how this wouldn't work, if the piece spins true AND assuming the 'mortise' is already centred correctly (possibly the elephant in the room). For safety I think this operation would have to be done using the tailstock's dead centre.
    – Graphus
    May 30 '20 at 5:52
  • Agreed on the centering of the mortise being the issue.
    – FreeMan
    Jun 1 '20 at 11:51

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