Copal 3 lens board question

[robertraymer]

The thread diameter on the shutter is 61.8mm. On mine the retaining ring is 65mm outside dimension, with a step to a larger diameter, and it is 9.5mm thick, which is thicker than your lens board, so if you had a 65mm hole, it would not tighten, and could spin freely.Attachment 202398

I currently have it mounted on a wood B&J board with a 65mm opening that it fits perfectly in, but will be moving it to a cambo board to use with a Legend 8x10 I just purchased. The outside diameter of the retaining ring and the inside diameter of the spacer are both 65mm. The outside diameter of the shutter is just shy of 62mm (I'm guessing your 61.8 measurement. So if I am understanding correctly, if you use a thick wooden board or a thin board and spacer, it requires a 65mm opening, with the retaining ring screwed all the way in and securing the board or the spacer/board, but if you have a thin board with a 62mm opening it will still work by securing the board between the shutter body and bottom of the retaining ring, but the ring will just not screw all the way down.

[DMS206]

I currently have it mounted on a wood B&J board with a 65mm opening that it fits perfectly in, but will be moving it to a cambo board to use with a Legend 8x10 I just purchased. The outside diameter of the retaining ring and the inside diameter of the spacer are both 65mm. The outside diameter of the shutter is just shy of 62mm (I'm guessing your 61.8 measurement. So if I am understanding correctly, if you use a thick wooden board or a thin board and spacer, it requires a 65mm opening, with the retaining ring screwed all the way in and securing the board or the spacer/board, but if you have a thin board with a 62mm opening it will still work by securing the board between the shutter body and bottom of the retaining ring, but the ring will just not screw all the way down.

Yes , that is correct, I probably didn’t explain it very clearly.
Dave