View Full Version : 74mm jam nut

31-Aug-2017, 15:39
74mm jam nut needed. Thin. This is to mount a focusing mount to one of my hand-built cameras.

I am at a loss to find the Right Thing. Due to my stupidity or old age I cannot nail it in a Google search. My shortcoming.

Any solid help would be appreciated, and if I can I will compensate the person with the correct answer from my clutter of old LF parts.


Drew Bedo
1-Sep-2017, 12:54
I am in the same boat.

Have a wollensak 15" f/5.6 Telephoto without mounting ring. A 75mm ring will cross-thread , but ultimately pops off. Right now electrical tape holds it on a lensboard, but is not what I want.

I can find rings with this thread, but they all cost over $100 , or quivilant of Diner for two at a nice restaurant in Houston.

Read my sig-line!

1-Sep-2017, 13:09
Hang in there, Drew. I am still looking, but here is Thor Labs retainer page (https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1535). It looks promising.

There are some surprising solutions including 'snap rings'.
Do you have an accurate gauge to measure diameter.

UPDATE: I found a perfect jam nut in my odds-n-ends box. 73.4mm ID.

UPDATE TO UPDATE: I visited our home town super manufacturer, Fastenal (https://www.fastenal.com) and found this. It might just work!