Questions on Waterhousestop Design

[Len Middleton]

OK, now need to sort out the design of the waterhouse stops for the two lenses I have that need them. I do have a set of waterhouse stops that do not fit either of my lenses, so I do have a reference to the traditional design.

I notice that the traditional design is a single opening with a tab to grip onto when inserting and extracting the waterhouse stop from the lens, rather than a double-ended "stick" with openings at both ends.

Is that a necessity with the light gauge metal used so that it does not bent with the longer length of a double-ended one, or is there another reason?

On the thicker set I do have, I noticed that the holes are tapered presumably to reduce diffraction. Is that required with a light gauge set?

I would appreciate any thoughts or insight.

[goamules]

It's a hole. You can make them out of cardboard. The bevel on period ones is common, but I'm not sure it wasn't there just as part of the manufacturing process.

[IanG]

As Garret says they are just a piece of metal or other material with a hole in, some more elaborate than others. In the past I've made mine from Aluminium as it's easy to work with, others use old dark slides from film/plate holders. I always make a cardboard template for each lens first then cut all the blanks first before drilling them.

I guess you could make them double ended but as they are thin and small anyway there wouldn't be that much of an advantage.

Ian

[Steven Tribe]

Black card is a good alternative to brass, aluminium or zink. I once bought a Euryskop with the original blackened brass WHS, but there was also a copy set in black card for real field use.

Oversize tabs are advisable to keep the light out of the barrel if the thickness is much less than the original slot.

[Jac@stafford.net]

Keep it simple. See how S.K. Grimes makes theirs here. I make mine from brass because I have the blackening chemistry, but Steve Tribe and Garrett's suggestion are probably better as you work out the sizing.

If you can tell us what lens you are working with we might have a similar barrel with stops we can measure or scan for you.

(By the way, it is Waterhouse stop, named after the inventor, John Waterhouse.)

[IanG]

Keep it simple. See how S.K. Grimes makes theirs here. I make mine from brass because I have the blackening chemistry, but Steve Tribe and Garrett's suggestion are probably better as you work out the sizing.

What are you using to blacken your brass ? I have brass sheet that I use for other things and an arsenal of chemicals.

Ian

[Jac@stafford.net]

What are you using to blacken your brass ?

Gravoxide that I got from our lab. By accident I found that some dish detergents will color-down brass. Palmolive comes to mind. But there are other ways.

[Len Middleton]

Thank you for the responses. Now on a computer, rather than Tapatalk...

Jac, I did get the name right in my first paragraph, but unfortunately not in the title, and could not figure out how to edit it in Tapatalk afterwards.

OK, so over thinking things again, but not an unusual situation for me...

Garrett, from a manufacturing point of view, if doing small quantities using a large cutter with an angled cutting surface like used in countersinks would make sense. One could use a single cutter for all hole sizes, but it would be necessary to manage the hole diameter through depth. For higher volume a fixed sized cutter (i.e. drill) for each hole size would be more effective.

Jac, thanks for the link to the SK Grimes site, as I forgot about that. Their design seems to cover the comments from Ian and Steve as well, and they use a cardboard template prior as suggested.

The lenses I have that need waterhouse stops are:

Voigtlander Euryscop #1 (ca. 1880's), and a

Ross No. 3 Universal

Now to get to doing it.

[Steven Tribe]

Thr standard method for blackening brass is as follows (Orford, ca. 1900).

Take concentrated nitric acid, dissolve granulated copper into it until there is no further reaction. Dilute with an equal amount of water. Heat the brass item to be coated in a bunsen burner or spirit lamp, being careful not to smoke them (plenty of oxygen!). Plunge into the solution. Hiss, hiss! Drain excess liquid. Burn the green deposit off (hydrate?) until it is black. Use a brush, when cold, to remove any caustic residue. Another system was to use normal shellac in methylated spirits which had had vegetable black (carbon) added.