Puzzled by 3/8" tripod mount on old wooden field camera

[tokyogaz]

Hi. First post, so my apologies if I break any guidelines...
I have a vintage Japanese wooden field camera, brand name of Ishibashi, probably dating from the early 20c (has dry plate holders). The tripod nut seems to be a 3/8 size, but my Gitzo 3/8 adapter won't screw in, and neither will a standard 3/8 bolt.
I suspect the pitch of the thread is 'non-standard'.
Correct me if I'm wrong, but I believe the standard 3/8 is 16 threads per inch for cameras and normal bolts. I'm wondering if the tripod nut my camera might be a 3/8-24TPI. Would that make sense?
Here's the camera...

[John Koehrer]

I've no claim to know anything about these but could it be a metric thread?
Over here I'd just run down to the local ACE & test fit. As you suggest, it may be a fine thread too.

[RichardRitter]

Yes 3/8- 16 is the standard. Your camera could have a 3/8-20 which was used in the 20's.

[tokyogaz]

Thanks for your comments.

John, I tried a metric M8, which seemed the closest size, but unfortunately no joy. Given the age and provenance of the camera, I suspect it must be an imperial size.

Richard, thanks for the intriguing tip. 1920s would probably be about right for this camera, so I suspect it is as you say 3/8-20. I'll have to see if I can find a suitable bolt and rig up some kind of adapter bracket.

I've got a feeling that's going to be a hard size to find here in Japan.

Thanks

[jp]

Go to a tool store and get a thread guage. It's sets of teeth you try over the thread to see what the thread measurement is. Looks like a feeler guage set or bland swiss army knife.

[GPS]

...

I've got a feeling that's going to be a hard size to find here in Japan.

Thanks

Com'on! It's internet age today - you can buy your screw easily from the net. If you knew its standard you wouldn't even need to move from your computer to get it...

[tokyogaz]

GPS,
I thought so too, but it's proving harder than I thought. 3/8-16 is everywhere, and I already have that. A single 3/8-24 I can get from a retailer selling through Amazon Japan, but with postage, that one bolt is costing about 10USD, a quarter of what I paid for the camera... and I'm not even sure it's the right size. And the one I think is the right size, 3/8-20, is nowhere to be found.... I'm starting to wonder if it may be easier to find a 1920s tripod head.

[RichardRitter]

If you have problems finding a 3/8 - 20 bolt let me know I had a custom die made for a job I was working on.

[tokyogaz]

Richard,

Thanks. I may take you up on that if I can't source one locally in the next week.

[John Koehrer]

What about running a 3/8-16 tap through it or would it screw up the mount?
In the past I've gone to a smaller size thread by gluing a screw in place & re drilling & tapping it.