Rear collar ring for my SK 90mm?

[Memento Mori]

Hey folks...I need the threaded collar that holds the lens tight to the lensboard, for my 90mm SchneiderK. It is 30mm measuring the threaded male section that the ring screws onto. Any ideas?

I had it screwed into a plastic board that sort of works but...
TIA, Kevin

[gypsydog]

S.K. Grimes

[Keith Pitman]

Look for a retaining ring in the appropriate Copal size on Ebay. Grimes would take care of it for you, but at two to three times the cost.