Bench grinder nut problem

[Jack in omaha]

I have a old gench grinder with a arbor says Maies
I took off the left grinding stone and when I went to jut the new stone on the same nut on it jams .
It starts fine but then stops it came off but wull not go back on I cleaened the threads on nut and arbor still jams
It has a fine thread.
So I suspect someone forced the wrong nut on a long time ago.
Sorry now I took it off but would it have been metric looks like ww2 vintage
I tried the nut from my right side it would not go on. So it is a fine left thread nut.
Any idea what is hapening here?

[brianwelch]

I have a old gench grinder with a arbor says Maies
I took off the left grinding stone and when I went to jut the new stone on the same nut on it jams .
It starts fine but then stops it came off but wull not go back on I cleaened the threads on nut and arbor still jams
It has a fine thread.
So I suspect someone forced the wrong nut on a long time ago.
Sorry now I took it off but would it have been metric looks like ww2 vintage
I tried the nut from my right side it would not go on. So it is a fine left thread nut.
Any idea what is hapening here?

Have you tried a lubricant? Tried flipping the nut over and trying from both sides?
I would try a brass brush on the arbor and a copper fitting brush on the nut, being sure to turn in the correct direction.
Not surprised that it is opposite hand from the other side...
Good luck

[Jack in omaha]

I did try. Very odd that it came off fine but will not go back. The threads on the arbor shaft look fine but I am not going to force it.
So I ordered a 1/2 20 left hand nut online since I can not go out.