Flange spacer that allows a large flange to fit on a smaller lensboard...

[Jay Decker]

The photos below show a lensboard that was built to accept a flange with a diameter greater than the wide or height of the lens board, i.e., the flange "overhangs" the sides of the lensboard. The spacer was cut from a material call phenolic paper, which is inexpensive and works easily. However, the spacer could have been cut from 3/32" thick plywood or other materials. The edges of the spacer were colored with a black "Sharpie" permanent ink marker for appearance.


3/32" thick Phenolic Paper spacer on top of the lensboard and flange:
http://monkeytumble.com/tmp/2d_spacer_2.jpg

Phenolic Paper spacer between the flange and lensboard during the trial fit:
http://monkeytumble.com/tmp/2d_spacer_5.jpg

Completed lensboard with the lens attached in the camera:
http://monkeytumble.com/tmp/2d_spacer_6.jpg


Another shot of the subject lensboard on the right that shows how far past the lensboard the flange overhangs:
http://monkeytumble.com/tmp/2d_spacer_12.jpg

[jan labij]

Well, very interesting. How strong is the phenol-paper, and where do you get it?

[jp]

It will be more rugged and stable than wood.

Phenolic is also used for circuit boards, so you could get a blank circuit board for the project. A truly blank one is made with a sandwich of the phenolic between sheets of thin copper; people design and etch them from there. There are also blank premade circuit board surplus or mistakes that are used for decorative items like notebook covers, etc... Green typically with the trace patterns and silver pads on them.

Depending on the lens size used, perhaps a toilet flange spacer could also be used?

[Jay Decker]

Well, very interesting. How strong is the phenol-paper, and where do you get it?

I purchased this material from Boeing Surplus near Seattle, which sells surplus material and tools from Boeing's manufacturing operations. It came in a 4ft x 4ft sheet that I paid $2 for. But, you can find the material all over the internet, eBay, electronic supply shops, etc.

[Len Middleton]

Jay,

What you do not show is how the lens flange is attached to the lensboard (e.g. self tapping screws, or screw and nut).

In either case, I would expect that your spacer is non-structural and no more than a spacer. Therefore the strength of the material is not relevant other than being rigid enough to handle the compression involved. Is that correct?

Looks like a good solution. For one large lens (600mm f9 Apo-Ronar CL), my friend chucked it up on his lathe and undercut the flange enough to get past the lensboard locking mechanisms.

Thanks for an alternate insight,

Len

[Jay Decker]

What you do not show is how the lens flange is attached to the lensboard (e.g. self tapping screws, or screw and nut).

The spacer is drilled where the screws pass through the mounting flange. The drilled holes are larger than the diameter of the wood screws that attach the flange to the lensboard. The spacer is held in place by the clamping action that occurs when the flange is screwed tightly to the wooden lensboard. And, it is also attached to a much less extent by flat black paint that is used to cover the exposed wood in the hole cut through the lensboard for the lens barrel, which "glues" the spacer to the lensboard.


In either case, I would expect that your spacer is non-structural and no more than a spacer. Therefore the strength of the material is not relevant other than being rigid enough to handle the compression involved. Is that correct?

You are correct, the spacer is non-structural as you have described.

[jan labij]

Thanks for the info on where to find the stuff.