Hello,

I recently picked up a 1950 Delta Multiplex 20-A RAS. The missing arbor nut and mandrel collar is what is holding me up though.
The 20-A manual from vintage machinery dot org states those parts are
a "special" 5/8-11 left hand thread. And the front mandrel collar is
5/8 bore and 1 3/4 x 1/8 thick.
The arbor is definitely not acme thread, looks like a normal thread.
There has to be some sort of more modern replacement saw part that would fit? Mcmaster-Carr has that nut but I thought I would see if anyone on here had any experience with actual parts before I go the online "hardware store" route.
I see a lot of 12 tpi 5/8. The 11 tpi 5/8 is much more elusive.