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How to fix overground nmtb50 arbor?


Feb 22, 2010
If you are going to rework an old arbor and the rework area is hardened, take the arbor to a heat treater and have them induction anneal just the area you need to machine, that should preserve the remaining hardness on the taper.

does that really work? you can induction harden, but anneal? usually you hold for an hour or more and even if not you cool slowly. by that time the whore part is annealed. or is there a trick to it?


Jun 25, 2016
Thx for all the info, I feel a little smarter now. Funny thing happened on the way to locating another arbor to cut down-found one in the rack that already has 10 tpi. Whatever was on those threads, we never had. It is 2 3/8 major dia so I’m thinking since I need 2 1/4-10, I’ll just take a new threading insert and shave 1/16 inch off those threads. And I’m sure they are hardened but a new very hard insert should cut them. I’m prepared to rethread like there are no threads there already but the lazy streak in me is wondering if just keeping the carriage disengaged would let the existing threads drive the toolpost, and thus carriage, along. Something tells me with much more pressure on one side of the thread groove than the other, the threading wouldn’t come out right. Anyone tried carriage-coasting like that?


Hot Rolled
Jun 22, 2008
That’s just going to break your insert, ever open the half nut a thread too early? Same result.


Jan 14, 2007
Flushing/Flint, Michigan
While I should not I will bite.
Move the flange downhill. Chop some off or the overall length. Thread deeper if needed but it should not be
Shorten the entire thing back into fit.

I would never consider trying to weld this unless emergency as much distortion.
Some do this with spray weld,... Not a fan.
.035 on diameter is reaching the limits of hard plate per side but maybe doable.