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View Full Version : Where can I find a knob or rod or bolt with 3/8 32 size?



Jon Shiu
3-Oct-2013, 18:10
A knob broke off when my old wooden tripod fell. The threaded post size, as near as I can tell, is 3/8" diameter and 32 threads per inch? Seems like an uncommon size now?

Jon

Richard Wasserman
3-Oct-2013, 18:14
McMaster-Carr has hex nuts that size—can you make that work? http://www.mcmaster.com/#hex-nuts/=os5vno

Amedeus
3-Oct-2013, 18:14
That is indeed an uncommon size. Standards are 3/8-16 and 3/8-24 ... looks like a custom job or possibly replace also the socket ...

Amedeus
3-Oct-2013, 18:18
McMaster-Carr has hex nuts that sizeŚcan you make that work? http://www.mcmaster.com/#hex-nuts/=os5vno


Funny they have the nuts but not the bolts or anything else that looks like a bolt in 32 TPI thread ...

Jon Shiu
3-Oct-2013, 18:29
Ack. My measurement was too crude. I'll try to get a more accurate gauge.

Okay, here are some new dimensions: the major diameter is .309" (about 5/16"?) and the thread is about 32 tpi as near as I can tell.

Jon

Leigh
3-Oct-2013, 19:07
... 3/8" diameter and 32 threads per inch? Seems like an uncommon size now?


That is indeed an uncommon size.
The 3/8"-32 thread is one of the most common in existence.

It's found on every volume control and similar control on (almost) every piece of electronic equipment ever made.
It's also used for the mounting bushings on rotary switches and other user controls.

Reid Supply carries a large assortment of knobs of various types, here: http://www.reidsupply.com/products/knobs-handles-hand-wheels/knobs/

Similarly, McMaster-Carr has knobs with threaded holes: http://www.mcmaster.com/#machine-component-knobs/=os6qfa

We need a better definition of what you want. A knob is not the same as a rod or bolt, unless you want one with a shaft attached.

- Leigh

Jerry Bodine
3-Oct-2013, 19:37
Ack. My measurement was too crude. I'll try to get a more accurate gauge.

Okay, here are some new dimensions: the major diameter is .309" (about 5/16"?) and the thread is about 32 tpi as near as I can tell.

Jon

Seems to fit in the UNEF thread series:
http://thread-chart.ueuo.com/UNC-UNF-UNEF-Thread-Specification.html

Leigh
3-Oct-2013, 19:48
Seems to fit in the UNEF thread series:
The 32TPI thread is used in every size from 1/8" diameter up to very large.

It's the standard "extra fine" thread in the imperial system.

- Leigh

mpirie
4-Oct-2013, 04:37
Could it be a metric thread?

3/8" is around 10mm.......if your camera is European, then it may be metric?

Mike

Bob Salomon
4-Oct-2013, 06:10
What brand tripod?

Jac@stafford.net
4-Oct-2013, 06:40
Leigh is right: we do need more information or perhaps a snapshot of the part.

I had a similar problem and replaced all the knobs on my wooden tripod with large ball knobs because they are so much easier to turn with arthritic hands.

Leigh
4-Oct-2013, 07:04
Could it be a metric thread?
Unlikely, though not impossible.

32 turns-per-inch works out to a thread pitch of about 0,794mm.
Rounding that to 0,8mm does not yield a standard thread, although 0,75mm is standard.

I checked the tap selection at McMaster-Carr and found that 10 x 1mm is standard, but 10 x 0,75mm is not.
A 1mm thread pitch works out to about 25 turns-per-inch.

- Leigh

(Formatted with comma separators rather than decimal points, per European usage.)

smithdoor
4-Oct-2013, 07:05
You can buy this nut try your local bot company
http://www.mcmaster.com/#95621a300/=osfsar
If that does not work you may need to make one not cheep I have had to make few in past for other tools. If you can not find what you please give me PM

Dave