Solutions for Whitworth thread tripod mounts

[Leigh]

That's why the good Lord invented Helicoils.

- Leigh

[Robert Bowring]

I have had to repair Helicoils too. (lots of fun). Tools can become deadly weapons in the wrong hands.

[Jac@stafford.net]

I think the Brits were the only ones who used Whitworth.

When Triumph Motorcycle decided to switch to more common fasteners, they chose American size, while in America there was an attempt to switch to Metrics! Go figure. (I had one of the rare Rickman Brothers' Rickman-Tridents. American fasteners except for a few which were Russian of a size nobody could match.)

[Leigh]

... a few which were Russian of a size nobody could match.)

Of course there are innumerable examples of proprietary threads in industry.

The most obvious one in photography is the Leica thread, which is 39mm with a 26tpi Whitworth thread.

- Leigh

[Robert Bowring]

My 1977 Bonneville has American, Whitworth and some metric. I always have the wrong wrench.

[Steve Smith]

How unusual! Is it a home-made camera?

What's unusual? Cameras traditionally had 1/4" and 3/8" Whitworth threads.

Some people have claimed that all tripod fasteners use Whitworth threads. That may be true.

Yes. I am one of those people! (well, not all... not now anyway).

From that fount of all knowledge, Wikipedia:

Screw thread

Per ISO 1222:2010, the current tripod screw thread standard for attaching the camera calls for a 1/4-20 UNC[2] or 3/8-16 UNC thread. Most consumer cameras are fitted with 1/4-20 UNC threads. Larger, professional cameras and lenses may be fitted with 3/8-16 UNC threads, plus a removable 1/4-20 UNC adapter, allowing them to be mounted on a tripod using either standard.

Historically, the thread standard for attaching older cameras to tripods was 1/4-20 BSW for smaller cameras or 3/8-16 BSW 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.

I think cameras with 1/4" BSF threads existed before UNC was unified and I don't see why German camera manufacturers would have used an American thread when they could use one in use throughout the whole of the British Empire!

It's very likely that tripod manufacturers use a thread optimised (I mean compromised) to fit both without causing problems. A while ago I found one tripod manufacturer who specified UNC and another using BSW (but I can't remember which manufacturers now).


Steve.

[Jac@stafford.net]

What's unusual? Cameras traditionally had 1/4" and 3/8" Whitworth threads.

You are right. In fact, I think you corrected me on this once before. The 1/4 x 20 and 3/8 x 16 we use on camera tripods are Whitworth standards. And the UNC versions are only 1 tpi different.

Thanks again.
Jac

[Steve Smith]

You are right. In fact, I think you corrected me on this once before. The 1/4 x 20 and 3/8 x 16 we use on camera tripods are Whitworth standards. And the UNC versions are only 1 tpi different.

The TPI is the same. 20 for 1/4" and 16 for 3/8. Only the cutting angle differs by five degrees.


Steve.

[Steve Smith]

That's why the good Lord invented Helicoils.

There used to be a very good motor engineering company near me. A few years ago a friend took in his van which needed a helicoil fitted in one of the spark plug threads. When he went back to get it he was told that they didn't have a proper helicoil so they had machined one from a nut which fitted the spark plug (M16 I think). It was a superb piece of machining and worked perfectly.

But because they didn't have a proper helicoil in stock, they refused to take any money for doing the job.


Steve.

[E. von Hoegh]

You are right. In fact, I think you corrected me on this once before. The 1/4 x 20 and 3/8 x 16 we use on camera tripods are Whitworth standards. And the UNC versions are only 1 tpi different.

Thanks again.
Jac

Nope. Same thread pitch, almost the same major and minor diameters, and five degrees difference in thread angle.
But I find it hard to believe that every camera and tripod maker ordered Whitworth standard tooling, especially when 1/4-20 (stovebolt) and likely 3/16-24 (carriage bolt) both predate the adoption of the Unified standard in this country.