Anti-rotation Screw Size

[Jason Lamar King]

You know those little screws that everyone asks" What is this screw sticking out of the back of my lens and is it safe to remove?" What size are those and where can they be purchased? Alternately I would like to know a sure fire way to stop a lens rotating in the lens board. It's already over tightened, still spins. Have two Fujinon an one Nikkor lens and only one screw.

[maltfalc]

make a washer out of thin leather or rubber if the retaining ring doesn't screw down far enough to grip the board on it's own.

[John Layton]

Two questions: One - do your lensboards actually have the recesses to accommodate those lock-screws? (as in Graphic lens boards?) And two - are your lens boards thick enough, and do they have appropriate diameter holes...to accommodate the diameters of the inner flanges of your retaining rings - while also being thicker than the depth of the inner flanges, to prevent these inner flanges from "bottoming out" on the rear surfaces of the shutters?

[Jeff Keller]

You can buy multi-size sets of tiny screws for eyeglasses on Amazon (I just did). I haven't tried fitting one into a lens, but I would be very surprised if there isn't one that would fit. If you take a lens with you and go to a friendly optician, you can probably find out the size and get some.

I'll try to check the size when I get home tonight.

Jeff

[nolindan]

You can use a screw with a 'drum' shaped head. Two common types are filister head and socket head screws. The threads on the shutter are probably metric but there is no shame in re-tapping the holes to proper American size threads.

These are available from McMaster Carr https://www.mcmaster.com/products/screws/

The screws supplied with shutters look like custom screws - which are very common and made on a 'Swiss screw machine' - google for videos of these machines.

[Keith Pitman]

I think John hit on the issue: it sounds like your lens board is too thin. As someone else suggested, make a spacer so the retaining ring will actually tighten up. I would forget about the anti-rotation screw as a solution.

[Jason Lamar King]

I think John hit on the issue: it sounds like your lens board is too thin. As someone else suggested, make a spacer so the retaining ring will actually tighten up. I would forget about the anti-rotation screw as a solution.

I'm using standard factory Toyo 110 boards for my 45A. I'd think it would work but I'll look into shimming it.

[Jason Lamar King]

You can buy multi-size sets of tiny screws for eyeglasses on Amazon (I just did). I haven't tried fitting one into a lens, but I would be very surprised if there isn't one that would fit. If you take a lens with you and go to a friendly optician, you can probably find out the size and get some.

I'll try to check the size when I get home tonight.

Jeff

Great idea let me know if one of them fit.

[Mal Paso]

Technically it's a stud not a screw which may help finding one. Tapping the hole for another thread is dicy with the shutter assembled. Blind holes require a bottoming tap and the skill to use one.

Tightening the lock ring should be enough. Most of my lenses don't have locating pins. I would cut shims if the lock ring doesn't tighten the lens.

[Jeff Keller]

Both the Copal 0 and Copal 1 use a 1.7mm diameter screw. The Seiko LS 26 (Copal 0 size) uses a 1.2mm diameter screw. The threads per inch isn't specified.
Neither of the two Copal 3 shutters that I have, have locating screw holes.

jeff

[Jason Lamar King]

Just a follow up for future readers of this thread. I ordered M1.6 x 0.35 mm Thread, 2 mm Long socket head cap screws part number 92290A847 from McMaster-Carr and they fit my Copal shutters perfectly. A few strokes of a file on my Toyo lens boards to make a notch to accept the screw head and my lenses are now rock solid. I would caution that the Toyo factory 110mm lens boards are thick enough that the screw head isn't protruding past the rear surface of the lens board so the retaining ring is able to tighten properly. If you have a thinner lens board the screw head may prevent the ring from tightening all the way. Also doing it this way it is possible that there will be a light leak but mine seem OK. Thanks for the replies and suggestions.