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1/4" - 3/8" Thread (1 Viewer)
- Thread starter orbec
- Start date
jmepler
It's just a flesh wound.
The threads used on tripod heads are UNC, Unified National Coarse.
Specifically 1/4-20 UNC and 3/8-16 UNC.
The 1/4 and 3/8 indicate the major diameter in inches.
The -20 and the -16 indicate threads per inch.
While these are the same size and pitch as British Standard Whitworth they are not interchangeable. BSW uses a 55° thread angle while UNC is 60°.
Mike
Specifically 1/4-20 UNC and 3/8-16 UNC.
The 1/4 and 3/8 indicate the major diameter in inches.
The -20 and the -16 indicate threads per inch.
While these are the same size and pitch as British Standard Whitworth they are not interchangeable. BSW uses a 55° thread angle while UNC is 60°.
Mike
gvca1
Well-known member
Interesting. The Wikipedia page on tripods says the historic standard is Whitworth. It would be interesting to hear from an engineer in the business what the tripod and camera manufacturers are actually using these days.
jmepler
It's just a flesh wound.
It also says "A BSW bolt in a UNC nut has play, but a UNC bolt in a BSW nut will jam."
I can tell you that a 1/4-20 UNC screw will fully engage the threaded socket of all of my cameras and scopes. This either indicates that they are all UNC or that, if the are BSW, the diameter is oversize to allow the use of either thread.
Wikipedia goes on to state "The camera is attached ... via quick release plate, or a simple UNC 1/4"-20 screw." This statement references this site.
Tomorrow I will measure a group of threaded adapters from my various tripods to determine whether they are UNC or BSW.
I have also contacted Manfrotto regarding which standard they use and will post their response should I get one.
I didn't realize that this was a controversial subject until I delved into it.
Mike
nirofo
Well-known member
The original camera, lens, and tripod standard threads are 1/4" x 20 and 3/8" x 16 Whitworth, although the equivalent UNC threads in the short sections needed for tripods etc will fit just as well and don't lock up, I've used both with no problems. If you have access to a lathe they are easy to make in either thread, just don't make the UNC ones too long, 3/8" is more than long enough for most fittings.
nirofo.
nirofo.
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jmepler
It's just a flesh wound.
I stand corrected
I just received a reply from the Technical Support Department at Manfrotto/Gitzo stating: "The threads on our tripods are British Standard Whitworth (BSW)."
That is definitive enough for me.
orbec, sorry I led you down the wrong path. I hope you didn't buy that tap yet. :h?:
You never know what you might learn on BirdForum,
Mike
I just received a reply from the Technical Support Department at Manfrotto/Gitzo stating: "The threads on our tripods are British Standard Whitworth (BSW)."
That is definitive enough for me.
orbec, sorry I led you down the wrong path. I hope you didn't buy that tap yet. :h?:
You never know what you might learn on BirdForum,
Mike
joespy
Well-known member
Tripod threads are BSW......Yes BSW are 55 degs and UNC 60 degs which means because dia. and pitch are the same, a UNC male will screw into a BSW female but not vice versa due to deeper thread depth.
Joe :t:
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