technical drawing of a lens barrel with Waterhouse stop slot...anyone got one?

[pjd]

I recently bought orphaned lens cells from a 15 1/2 inch series ii Velostigmat. The glass isn't in good condition, but I'm going to see if I can get a barrel made by a local machinist.

The machinist does work to spec, but isn't a photographic expert so he'll not know about lens flanges or a waterhouse slot. He also doesn't speak English, so I think it'll be good if I can take a diagram with specifications. I've been given some measurements to work with (thanks Mark), does anyone have a diagram of a lens barrel that I could adapt a bit? I don't think scale is important, I can add my own measurements and let it be known that it's not to scale. Drawing a barrel isn't so hard, but a diagram of a flange looks tricky to draw by hand without drafting equipment.

I have googled a bit without finding anything usable. Sorry if I've missed an obvious source.

Before someone suggests SK Grimes, I'm in another continent and the lens cells aren't in good enough condition to warrant that level of cost.

Thanks for reading!

[Steven Tribe]

CCHarrison's website has an extended section on Petzvals and shows a real photo of Alex's "1/2" lens. This is a lens cut down the middle exposing a cross section of lenses and brass. This gives a very good impression of the brass machining which is necessary to install the internal baffle/guide for Waterhouse stops.

[Nodda Duma]

Careful about providing a machinist napkin sketches. You may get lucky and get what you want, but you likely won't.

The machinist would expect a dimensional drawing rendered from a CAD model, with tolerances and finish information. If the machinist runs a CNC, he'd also prefer the CAD file. I'm guessing he machines by hand, tho.

If you have a buddy who's a mechanical engineer, he/she could do that fairly quick (like over a weekend) in Solidworks. But you'd want to give them something for their time.

Regarding finish: you'll want to blacken the inside of the barrel to mitigate stray light, so recommend you request aluminum (Type 6061) and black anodize finish, or brass with blackened interior finish.

[Dan Fromm]

Hmm. A black anodized smooth surface is quite shiny. One way to reduce reflections from the inside of the tube is to put baffles in. Another is to cut grooves in the tube's inner wall, then anodize. And another is to line the tube with flocking paper as is sold by Edmund Optics.

[Bob Salomon]

Hmm. A black anodized smooth surface is quite shiny. One way to reduce reflections from the inside of the tube is to put baffles in. Another is to cut grooves in the tube's inner wall, then anodize. And another is to line the tube with flocking paper as is sold by Edmund Optics.

What about this then? One is a 210 Apo Sironar N one is a 65 4.5 Grandagon N and the little one is a Rodagon.

[Dan Fromm]

Its hard to tell, Bob, but the barrels' interiors seem to be a matte black. Smooth black anodized isn't matte black.

[Bob Salomon]

Its hard to tell, Bob, but the barrels' interiors seem to be a matte black. Smooth black anodized isn't matte black.

They are shiny metal where they are cut and you can't see what they are like inside the lens, but all visible interior parts visible are matte black.

[Jac@stafford.net]

Black flocking paper works perfectly well. It is entirely non-reflective dead-black. If it gets dusty in time, just pat it with the sticky side of masking tape to lift off the dust.

Regarding the guides for the Waterhouse stop: The machinist can cut two short lengths from the barrel work piece, then cut off a section in each so they clear the width of the Waterhouse slot. Then push them inside into place, one on each side of the slot. They will gently conform to the inside of the barrel. Good to go. Solder them in place if you like. An alternative is to just cut one length from the barrel workpiece, cut it so it will just slide into the barrel, then cut the Waterhouse stop through the barrel and the cut piece.

(The Waterhouse stop should be cut to about half the diameter of the barrel, and the stops should look like these.) Credit: Wollaston

[Steven Tribe]

Black flocking paper works perfectly well. It is entirely non-reflective dead-black. If it gets dusty in time, just pat it with the sticky side of masking tape to lift off the dust.

Regarding the guides for the Waterhouse stop: The machinist can cut two short lengths from the barrel work piece, then cut off a section in each so they clear the width of the Waterhouse slot. Then push them inside into place, one on each side of the slot. They will gently conform to the inside of the barrel. Good to go. Solder them in place if you like. An alternative is to just cut one length from the barrel workpiece, cut it so it will just slide into the barrel, then cut the Waterhouse stop through the barrel and the cut piece.

(The Waterhouse stop should be cut to about half the diameter of the barrel, and the stops should look like these.) Credit: Wollaston

This system (using barrel brass pieces) will only work if you are prepared to cut a Waterhouse slot almost half way through the barrel to allow full width entry of the WH stops. Cut the slot before you try and install one or a pair of baffles.

[Nodda Duma]

Hmm. A black anodized smooth surface is quite shiny. One way to reduce reflections from the inside of the tube is to put baffles in. Another is to cut grooves in the tube's inner wall, then anodize. And another is to line the tube with flocking paper as is sold by Edmund Optics.

Sorry, incorrect. A black anodized surface is as shiny as the finish callout allows it to be.

There's various ways to call it out but the specific callout I'm using on a recent lens barrel which received a satisfactorily flat black anodize finish is:

Finish: Hard Anodize per MIL-A-8625. Type III, Class 2, Color: Matte Black (or Lusterless Black)

But your comment does highlight that it's very easy to not get what you want if you don't think of the details.