Ring/Flange for Alphax #3?

Hello All,

I am trying to find a flange or retaining ring to fit an Alphax #3 shutter. The thread specs are: 3.117 inch diameter and 30TPI. I am looking for a lower priced alternative to units available from Grimes and e-bay (fall-back plans B & C).

I am willing to re-purpose something in the short run.

Typo alert: The shutter is an Alphax #5. The Thread dimensions are as posted above 3.117"/ 30 TPI.