Lenses slipping on boards

I have a couple of lenses that want to slip on the lens board when I handle the board. Any stopping down that I do has to be done from outside the darkcloth. Is there a way to prevent this? The lenses are a Kodak 203 mm which is on a Toyo 4x4 board and a 159 mm Wollensak on a wooden 6x6 board.

Hi there,

Besides 'tighten them down' both of those lenses should be in shutters that take an extra screw in the back that fit into a dimple in the lens board, Supermatic & Rapax.

A quick fix is to make a cork gasket just smaller than the aperture ring and just smaller than the rear threads so it is a push-on fit to the shutter. Tighten them down snug and the extra friction will hold. You can find 1/32" cork gasket at any auto parts store.

Good luck.

Thanks!