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el pescador
28-Jan-2017, 04:38
hope this is the right section for this question, I'm making up an L bracket to mount my shen hao 617 vertically on a tripod. The base of the camera has 2 threaded holes one is the standard 1/4" whitworth thread but the other is larger probably 3/8" is this likely to be whitworth thread as well, or is it 3/8" UNC?

LabRat
28-Jan-2017, 05:15
3/8" 12tpi UNC is the larger one... I think the whitworth is the same, as the origin of this common size is from the old carriage making trade and one of the most common sizes...

The smaller is 1/4" -20 NC...

Steve K

Randy Moe
28-Jan-2017, 05:48
3/8" 12tpi UNC is the larger one... I think the whitworth is the same, as the origin of this common size is from the old carriage making trade and one of the most common sizes...

The smaller is 1/4" -20 NC...

Steve K

3/8" X 16 tpi

https://www.boltdepot.com/fastener-information/measuring/us-tpi.aspx

LabRat
28-Jan-2017, 06:31
3/8" X 16 tpi

https://www.boltdepot.com/fastener-information/measuring/us-tpi.aspx

Thanks for the (correct) correction, Randy... Me brain bad!!! (Go figure, I knew that...) :-&

Steve K

Tav Walraven
28-Jan-2017, 07:24
Just to add a note, stay away from the 3/8x24 fine threaded variety and also stainless steel as it is more prone to gall. I would choose a Grade 8 3/8 x 16.

el pescador
28-Jan-2017, 08:03
thanks for that everyone, I should have thought to check the T.P.I. on each one both unc & whitworth are both 16 tpi. I have ordered a couple of bolts so thats sorted that part of the job

Leigh
28-Jan-2017, 10:02
...both unc & whitworth are both 16 tpi.
Apples and oranges.

UNC (and UNF and similar) define the size of a thread, both its diameter and its pitch.
There's a whole long list of threads in those standards.

Whitworth refers only to the shape of the thread, not its diameter or pitch.
Specifically, the included angle is 55 degrees, as compared with 60 degrees for American (UN*) threads.

Threads of the two standards will inter-mate unless the tolerance is quite tight.

- Leigh