Snapped screw / pin (1 Viewer)

[jmepler]

Hi,

Wikipedia and as it seems, ISO beg to disagree... 1/4-20 UNC or 3/8-16 UNC...

Tripod (photography) - Wikipedia

en.wikipedia.org

But I have to admit that I didn't spend 38€ for the privilege to actually check the ISO text...

Joachim

We had discussed this ten years ago here. Because of this discussion, I asked the Technical Support Department at Manfrotto/Gitzo about thread standards. They stated that "The threads on our tripods are British Standard Whitworth (BSW)."

According to someone who claims to have purchased ISO 1222:2010, the standard is 1/4-20 UNC.

I wouldn't be surprised if camera and scope manufacturers are using 1/4-20 UNC threads, this would work with either UNC or BSW screws. Conversely, tripod manufacturers might be using 1/4-20 BSW on tripods for backward compatibility for old cameras and scopes.

 

[jring]

Hi,

interesting... that's what international standards are for... to be ignored by industry... almost 50 years after adoption of said standard in 1973...

Here is a link to a pdf version of ISO-1222-1987 which refers to the first edition from 1973 and also clearly shows the UNC threads...

https://cdn.standards.iteh.ai/samples/5836/d4306c68270e476eaea3fba711a65dea/ISO-1222-1987.pdf

Reading the standard linked above, note footnote 3 on page two (of two - yeah, your really get your money's worth with that one) - they actually loosened the tolerances even more than UNC class 1A / 1B (loose fit for manual assembly) in order to ensure the compatibility with exiting gear from different countries...

Joachim

 

[jmepler]

I just measured the threads on a Manfrotto 200PL-14. They are clearly 1/4-20 UNC. Not sure where the person that I spoke to at Manfrotto was getting the information that they were BSW.

The fact that we need to pay to see international standards is ridiculous to me. I haven't seen any that were worth what ISO was charging for them.

 

[richard866945]

Hi,
Wikipedia and as it seems, ISO beg to disagree... 1/4-20 UNC or 3/8-16 UNC...
But I have to admit that I didn't spend 38€ for the privilege to actually check the ISO text...
Joachim

Hello Joachim
The thread pitch of Whitworth and UNC is the same up to but not including 1/2 inch.
Whitworth threads have a 55 degree angle and rounded crests.
UNC have 60 degree flattened crests.
That might explain why some mismatched bolts wobble or unscrew more easily in use.
Richard