Agfa Billy Clack not-quite-3/8 tripod mount

jay moussy · Dec 3, 2021

The tripod mount on my billy Clack is *like* 3/8, but not quite.
I bought a 3/8 to 1/4 adapter mail order, but the part does not engage past three-quarter of a turn, then I need to stop.

I read somewhere that these like-3/8 may be a British standard pitch, so no go on standard 3/8.

This is a camera I use, no a self item, so I can modify as needed. Very light in weight.

What are my options?
- cemented filler, formed to take 1/4, method TBD
- filler as anchor the thin sub-plate, accepting 1/4 nut
- 1/4 nut, rounded edges, secured in tripod mount hole, with some cement
- other?

Donald Qualls · Dec 3, 2021

The cameras I have with a 3/8 thread diameter are the standard 3/8-16. I've use hardware store bushings to adapt from this thread to 1/4-20 for standard tripod screw on several cameras. They run in until they bottom out in the socket or the flange touches down.

Your Clack might possibly have a metric thread, but getting a bushing to go from, say, M9.5 or M10 to 1/4-20 may require a deep search. Know anyone with a lathe?

Peltigera · Dec 3, 2021

Whitworth is a standard British thread pitch - the very first British standard thread, in fact.

Donald Qualls · Dec 3, 2021

Whitworth standard pitch for 3/8" diameter is still 16 threads per inch. Whitworth threads, however, are 55 degree rather than the 60 degree of UNC/UNF and metric threads; if there's little diameter tolerance this could cause binding.

What I see as the flaw in that idea is that the Agfa Clack was made in Germany, not the UK; if they weren't adhering to the (US-originated) 3/8-16 tripod thread, why would they choose to use Whitworth instead of metric?

Petrochemist · Dec 3, 2021

Donald Qualls said:
Whitworth standard pitch for 3/8" diameter is still 16 threads per inch. Whitworth threads, however, are 55 degree rather than the 60 degree of UNC/UNF and metric threads; if there's little diameter tolerance this could cause binding.

What I see as the flaw in that idea is that the Agfa Clack was made in Germany, not the UK; if they weren't adhering to the (US-originated) 3/8-16 tripod thread, why would they choose to use Whitworth instead of metric?

I've heard whitworth threads fit in the sockets fine, but it makes sense that the reverse is not true. Male UNC threads don't fit female whitworth sockets.
I'm guessing the folks at Agfa just made a 3/8-16 thread using the nearest standard (British Whitworth) without checking thoroughly - after all most sources still just quote "3/8-16".

If you can get a UNC 3/8-16 bottoming tap it should be fairly trivial to modify the thread on the camera (much easier than having a custom adapter)
Likewise with a suitable Whitworth die you can modify the threads on a purchased adapter. I'd consider this the better option, but I'm in the UK where whitworth dies are easier to find than UNC taps....

Nicholas Lindan · Dec 3, 2021

I'm with Donald - it's probably Metric if it's not 3/8-16 as, after all, it is a German camera - someone may have shoved an M6 tap up it's, er, private parts. I have never heard of a camera using a metric tripod thread from the factory. 3/8-16 is a Whitworth size but I have never heard of a camera using a BSW thread instead of UNC.

If it were my camera I would take a 3/18-16 tap to the camera (probably need a "plug tap"), shove in some epoxy and then screw in a 3/8->1/4 adapter. In my tripod collection it is only the big guns - like Ries and Gitzo Studex - that have a 3/8-16 thread mounted in the head.

--

I just took a look at the base of a Clack - damned it that doesn't look like a 1/4-20 (which is what one would expect on a small camera). Maybe someone did drill out and metricize the OP's example. https://www.flickr.com/photos/50678983@N00/272119833/in/pool-camerapedia/

jay moussy · Dec 3, 2021

For reference my mail order adapter was:
Wimberley BS-100 3/8"-16 to 1/4"-20 Brass Reducer Bushing

No taps on hand, Brit or other, only epoxy...!
Camera body is (pre-WWII) nickel-plated.

Petrochemist · Dec 3, 2021

It might be useful to add this snippet I found on Wikipedia:
'Historically, The Royal Photographic Society recommended the thread standard for attaching older cameras to tripods was 3/16-24 BSW (3/16 inch nominal diameter, 24 threads per inch), or 1/4-20 BSW [4] for smaller cameras and 3/8-16 BSW[5] for larger cameras and pan/tilt heads. In this application, the BSW and UNC thread profiles are similar enough that one can mount a modern camera on a legacy tripod and vice versa. The UNC threads are a 60-degree angle and flattened, whereas the BSW are a 55-degree angle and rounded crest. However, at least one English manufacturer uses No.1 B.A. (British Association) for its tripod mount thread.'

Petrochemist · Dec 3, 2021

jay moussy said:
For reference my mail order adapter was:
Wimberley BS-100 3/8"-16 to 1/4"-20 Brass Reducer Bushing

No taps on hand, Brit or other, only epoxy...!
Camera body is (pre-WWII) nickel-plated.

I wouldn't trust epoxy when spanning from 3/8 to 1/4.
Over the years I've ended up buying several taps/dies in US sizes that are not generally available locally (1/4-28, 1/4-20, 1/4 NPT...) in each case the tool has been fairly trivial in price & has usually cost significantly less than any adapters or even simple bolts pre made in the US thread.

MattKing · Dec 3, 2021

Is there any chance that the mount is either partially blocked or shallower than usual?

Nicholas Lindan · Dec 3, 2021

Petrochemist said:
I wouldn't trust epoxy when spanning from 3/8 to 1/4.

Ah - my quote on the epoxy was if one had to re-tap to 3/8-16 a hole that had been re-tapped to M6 from some other size and then inserted a 3/8->1/4 bushing; without the epoxy there may not be enough thread engagement possible to secure the bushing.

Nicholas Lindan · Dec 3, 2021

Petrochemist said:
It might be useful to add this snippet...: "Royal Photographic Society...the thread standard for attaching older cameras to tripods was 3/16-24 BSW..."

Now that's interesting, I'd never heard of it. The OP does state it is a pre-WWII metal camera, don't know if that is 'older' enough.

But that would correlate with the observation that a 3/8-16 goes in for a little bit and then stalls.

The solution may, again, be to re-tap for 3/8-20 and secure a 3/8->1/4 adapter bushing with epoxy or the goop of your choice. There won't be a lot of thread left after the re-tap and screwing the adapter bushing tightly may strip the hole.

Donald Qualls · Dec 3, 2021

@Nicholas Lindan Most of the adapters you'll be able to get, at least in North America, for 3/8 to 1/4 will be 3/8-16 (UNC) outside, not 3/8-20 (UNF).

gone · Dec 3, 2021

I think this Devcon epoxy would work, even w/ that tight tolerance. Its never failed me, we used it to repair cracks in carburetors and transmission housings. Your camera is pretty light too, wouldn't try it w/ a 4x5. They make much smaller sizes of this stuff w/ a syringe for around $10-$15. I've used it to permanently mount adapters, or on heavy duty auto/marine jobs, you name it.
https://www.zoro.com/devcon-epoxy-a... feed&utm_content=free google shopping clicks

Yes, good old Sir Joesph Whitworth, or Loose Screw Joe as he was known.. He and Lucas (the Prince of Darkness!), along w/ positive a battery ground, meant the first Triumph would be my one and only project bike.

Donald Qualls · Dec 3, 2021

momus said:
Yes. good old Whitworth. He and Lucas (the Prince of Darkness!), along w/ positive a battery ground, meant the Triumph would be my one and only project bike.

Try dealing with that when it's your daily driver car, and only the second one or third one you've owned... At least Rover had abandoned positive ground by the time my 2000TC was built in 1970...

gone · Dec 3, 2021

Eeek, you're right. That may explain the odd threads too, I don't remember my Clack having issues w/ that.

I did Donald. Had an old British MG or something sports car. Well, 2 of them actually. One to drive, when it ran, the other for parts. You really need 3.

jay moussy · Dec 3, 2021

The bu

MattKing said:
Is there any chance that the mount is either partially blocked or shallower than usual?

Yes, it may.
It looks pretty shallow, but not to the point of preventing bushing mount.
Being shallow will impact whatever fix I apply, less grip surface.

MattiS · Dec 3, 2021

Very interesting. My pre-war Zeiss ikon accepts the "modern" style 3/8" to 1/4" adapter (left), the 1930 Voigtländer (right) doesn´t. But both accept the vintage style adapter shown in the second picture. That´s the way to go.
And - there is no metric tripod mount, but obviously two different 3/8" tripod threads with slightly different pitch.

Donald Qualls · Dec 3, 2021

MattiS said:
1930 Voigtländer (right) doesn´t.

That's very odd -- I have a ca. 1927 Voigtlander Rollfilmkamera that has a bushing in the body tripod socket. The bushing is bottomed, due to being too long, but it screwed in as far as there are threads.

EDIT: should clarify, it's a bushing I bought as a photo part and installed myself...

Nicholas Lindan · Dec 3, 2021

Donald Qualls said:
@Nicholas Lindan Most of the adapters you'll be able to get, at least in North America, for 3/8 to 1/4 will be 3/8-16 (UNC) outside, not 3/8-20 (UNF).

You are quite right - "3/8-20" was a typo on my part. I think though that 3/8 UNF is 24 tpi.

It looks like what is needed is a 3/8-24 to 1/4-20 bushing adapter.

And, I'll be damned, you can buy such a thing https://www.mscdirect.com/product/details/06847222

Petrochemist · Dec 3, 2021

Donald Qualls said:
That's very odd -- I have a ca. 1927 Voigtlander Rollfilmkamera that has a bushing in the body tripod socket. The bushing is bottomed, due to being too long, but it screwed in as far as there are threads.

EDIT: should clarify, it's a bushing I bought as a photo part and installed myself...

It may have been designed to hold an ever ready type case, with the extra length required due to the leather of the case.

Donald Qualls · Dec 3, 2021

Nicholas Lindan said:
3/8 UNF is 24 tpi.

I see 3/8-20 all the time -- if you have a power drill with a 3/8 spindle for the chuck, that's the thread it'll have.

Donald Qualls · Dec 3, 2021

Petrochemist said:
It may have been designed to hold an ever ready type case, with the extra length required due to the leather of the case.

Actually, I just think the sockets on the Rollfilmkamera are on the shallow side.

runswithsizzers · Dec 3, 2021

jay moussy said:
The tripod mount on my billy Clack is *like* 3/8, but not quite.
I bought a 3/8 to 1/4 adapter mail order, but the part does not engage past three-quarter of a turn, then I need to stop.
[...]

Is the 3/8"-to-1/4" adapter the only thing you have tried? Before going to any great effort, I would try to confirm what is the exact thread of your camera - either by measuring with a screw pitch gauge, or by trying bolts of known thread size. As a famous lady once said, "One accurate measurement is worth a thousand expert opinions."

Nicholas Lindan · Dec 3, 2021

runswithsizzers said:
As a famous lady once said, "One accurate measurement is worth a thousand expert opinions."

Makes you think she hung out on Photrio...

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