Mounting a lens on a Beseler 45

Seems I keep stumbling over my ignorance/inexperience . . .

I came into darkroom (hobby) work by way of a Bogen enlarger with a threaded port on the enlarger head -- no lens boards. So I made some assumptions.

Several years ago (just before I got diverted from photography), I picked up a Beseler 45MCR with all the parts except lens boards. I also picked up a 135mm Componon-S which has both 50mm and 42mm threads.

Fast forward to yesterday. I'd placed a B&H order, so I added in a lens board with 50mm bore. That arrived yesterday, and I found that my assumption that lens boards were threaded was incorrect.

The only picture I've been able to find so far of a Schneider jam nut looks a bit like a bushing -- wider flange on one end to press against the lens board. I see other jam nuts on sale, but they don't look like that. Can I use them somehow?

Related question: the lens board hole is closer to 52mm. Am I correct to assume this is the right thing and "50mm bore" is shorthand for "bore sized for 50mm threads plus a jam nut"?

Also, the threads have about the same depth as the lens board thickness, so they do not extend past the board. Is this the reason that there are also boards with a surface counterbore?

It will be at least several months before I have the space to use this enlarger, so this isn't time critical. But I want to get it all together at some point.

If you have a lens with a 42mm thread one would think it would be easy to mount a 42mm lensring onto the lensboard.
There must be thousands of them around taken from old Zenit's and so on.
In that way you just could srew-in your lens to the lensboard of your enlarger.
Ask your local repair-man for one.

Peter

I had forgotten that the 135 Comp-S had both threads.... The most common combo, of course, is the 39mm thread through a 42mm board hole (jam nut being about 45mm outside diam). I assume that the 50mm jam nut is meant for that thread combo and the outer dimension of the jam nut fits correctly around your board hole. It seems you could simply get the larger jam nut to make use of your board. I've mounted some odd combinations by simply fabricating a board blank and mounting the custom flange hardware to to it and keeping the proprietary pieces together but yours is a quite common combo that should just need the right jam nut to mount.

I hope I'm thinking straight.... I slept in on a day off and am just starting a first coffee as I type!