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Problem identifying a thread

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Dave Castle29/12/2013 16:34:43
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New to the Forum and to proper engineering. I need some advice please.

I do a bit of photography and have a tripod head I want to modify. The head has a clamping handle with a female thread which screws onto a fixed stud. I want to make another handle so need to make a new female part to fit the existing stud.

I think the thread is metric M10x1.5. I have a set of metric taps and dyes and the 1.5 thread checker fits the male stud perfectly. A piece of M10 all-thread fits the stud like a glove. Angle, pitch and thread depth all match. The major diameter of the stud and the all-thread are both 9.7mm.

But...an M10 nut that fits the all-thread won't fit the stud and the all-thread won't fit the female thread in the handle. It's not that they are a poor fit, they won't even start. I have wiggled and wangled to no avail. I am stuck. Any ideas on what is happening and what I should do next?

Many thanks.
Dave

JasonB29/12/2013 16:49:27
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Some camera stuff uses 3/8 x 16 UNC which may be a possibility

See this

3/8 Whit would also be worth looking at thats also 16tpi as 1/4 whit is quite common on the base of cameras,

Edited By JasonB on 29/12/2013 16:50:01

Michael Gilligan29/12/2013 17:00:15
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Posted by JasonB on 29/12/2013 16:49:27:

Some camera stuff uses 3/8 x 16 UNC which may be a possibility

See this

3/8 Whit would also be worth looking at thats also 16tpi as 1/4 whit is quite common on the base of cameras,

Edited By JasonB on 29/12/2013 16:50:01

.

Jason,

Forgive me correcting you [and your source], but the 1/4" and 3/8" camera attachment threads are both internationally standardised as Whitworth.

... but, of course that doesn't help solve Dave's problem with the handle thread.

MichaelG.

.

Edit: Does anyone have access to the DIN standard quoted in Jason's link ??

Edited By Michael Gilligan on 29/12/2013 17:05:28

Michael Gilligan29/12/2013 17:13:10
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I may live to regret that last post ... because I have now seen several pages that state the Tripod Threads to be 60°

But, I haven't yet found the source document.

MichaelG.

.

P.S.  Useful comment, here.

Edited By Michael Gilligan on 29/12/2013 17:16:44

Michael Gilligan29/12/2013 17:20:26
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Dave,

As a matter of interest: What make/model/age is the tripod head ?

MichaelG.

JasonB29/12/2013 17:24:06
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Michael, this seems to suggest that ISO 1222 is more upto date and uses the UNC form, see part way down about threads

Michael Gilligan29/12/2013 17:36:46
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Jason,

Yes ... that's what I was admitting to.

MichaelG.

Dave Castle29/12/2013 18:17:57
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Thanks for the link Jason. The 3/8 x16 UNC thread is very close to the metric. May be a case of so near and yet so far. I had not realised how many threads there were or how close some of the dimensions are. Have to start learning sometime.

Michael, the head is a Gitzo GS5120LVL about 10 years old.

Thanks for your prompt and useful replies.

Dave

Michael Gilligan29/12/2013 18:28:11
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Dave,

I have a couple of Gitzo heads ... but both are older than that, so may not be much help.

MichaelG.

.

Edit: This might be useful reference

 

Edited By Michael Gilligan on 29/12/2013 18:54:03

Michael Gilligan29/12/2013 20:29:44
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Dave,

I've been pondering this, and I think the most likely answer is that the head was built with 3/8" Whitworth threads [i.e. to the original standard].

Given your comment at 18:17:57, I presume you are not too familiar with the various thread forms.

Sorry to labour this, but:

  • M10 x1.5 pitch is indeed close to 3/8" x 16 tpi
  • 3/8" UNC, and 3/8" Whitworth are both 16 tpi
  • Metric threads have 60° angle
  • Unified threads also have 60° angle ... but
  • Whitworth threads have 55°

Thus it is likely that a "loose fit" M10 will fit 3/8" UNC, but much less likely that it will fit 3/8" Whit. [try drawing it to scale and you will see why]

I would suggest that you repeat your "trial fit" exercise using a 3/8" Whitworth nut and bolt.

... if you can't find parts to try, I may be able to help ... Where are you?

MichaelG.

.

 

 

 

 

Edited By Michael Gilligan on 29/12/2013 20:32:02

Saxalby29/12/2013 20:32:45
173 forum posts
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Hi,

I have just checked the thread (with thread gauges) on my Gitzo GS5121LVL head and it is 3/8 X 16 UNC. My old plate camera's do have 3/8 X16 BSW, and will still fit on the Gitzo heads.

Hope it helps.

Barry

Michael Gilligan29/12/2013 20:54:05
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Oh well ... Bang goes my theory [or, some of it].

Well done, Barry

MichaelG.

Edited By Michael Gilligan on 29/12/2013 20:57:44

Dave Castle29/12/2013 21:12:39
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Barry and Michael,

I am interested to use this as an opportunity to experiment and learn something about threads and how to make them. So I have ordered taps and dies for 3/8 BSW and UNC so will have a play. I am a bit new to this but I have got to start somewhere. My reference is Drills, Taps and Dies by Tubal Cain. From Barry's research I am expecting the UNC thread to do the job.

I am amazed at the time and effort you Guys have given me. Thank you.

Dave (I am in Worcestershire)

Michael Gilligan29/12/2013 22:17:57
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Dave,

You're very welcome

Based on Barry's measurement, I'm sure it will turn out to be a UNC thread.

The new ISO Standard apparently specifies a loose [Class_1 ?] fit, at which UNC and Whitworth will each fit the other ... obviously essential for compatibility of old & new cameras & tripods.

Do let us know how you get on.

MichaelG. [in Cheshire]

Gone Away30/12/2013 01:40:31
829 forum posts
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If the measured OD of the male thread is indeed 9.7mm (=0.382" then I'm a bit sceptical that it is a 3/8 UNC.

Commercial UN threads invariably measure noticeably less than their nominal diameters ... probably because the UN spec allows truncation of the thread crests which is usually taken advantage of by the manufacturer. Even without truncation, 0.382" would be out of spec for the thread.

Being in Canada, I work (and have worked) with UN threads most of the time (although I'm getting kind of fond of Metric) and I can't ever remember seeing one as large as the nominal OD let alone larger. I just measured a bunch of 3/8-16 UNC bolts/threaded-rod in my shop and got diameters from 0.360 - 0.370 inches.

Moreover, the difference in pitch between 1.5 mm and 1/16" is significant (.050" in an inch). Unless the stud and handle have extremely short thread lengths, the mismatch (between 3/8-16 UNC and 10x1.5 mm) on offering the pair to each other should be obvious.

JasonB30/12/2013 07:50:17
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They usually only have about 3 turns of thread at the most so not much to compare with and why would a well known make of tripod not use the same threads that are used worldwide.

J

Michael Gilligan30/12/2013 07:52:31
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Posted by Dave Castle on 29/12/2013 21:12:39:

... I am interested to use this as an opportunity to experiment and learn something about threads and how to make them. So I have ordered taps and dies for 3/8 BSW and UNC so will have a play. I am a bit new to this but I have got to start somewhere. ...

.

Dave,

That's a very good way to start

Meanwhile, this Wikipedia page about Unified Threads has a very good explanatory drawing, and a brief but useful comment about Classes of Fit.

MichaelG.

Michael Gilligan30/12/2013 08:13:11
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I've just found these useful charts about Tolerance Class 1

1A 1B

... it's a very loose fit !

MichaelG.

Nicholas Farr30/12/2013 13:37:59
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Hi, while all the Whitworth and UNC threads from 1/4" to 2" with the exception of 1/2" have the same TPI and allthough not ideal in highly stressed parts the standard nuts are, in my experence, mostly interchangeable. I've known fitters who have mistaken both 3/8" Whitworth and UNC threaded rod as M10 because they find a M10 nut screws onto them easily, and the same goes for 3/4" Whitworth and UNC and M20 nuts, but when I've pointed out to them how sloppy a fit they are and then comparing the proper nuts that do fit, which will not screw on a know M10/20 thread, they soon realise thier mistake. The standard length of Metric threaded rod is always I Meter length, whereas the standard length of Whitworth and UNC is 3Ft.

Below is a photo of an M10 bolt with an attempt to screw on a 3/8" UNC nut and a 3/8" UNC bolt with an M10 nut screwed on happily.

boltsnut.jpg

The photo below shows a 1/4 UNC socket head bolt with a 1/4" Whitworth brass and steel nut happily screwed on.

uncwhit.jpg

Regards Nick.

Edited By Nicholas Farr on 30/12/2013 13:40:47

Harry Wilkes30/12/2013 15:24:18
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Hi Dave I find this chart very useful when trying to identifying threads, http://www.watchman.dsl.pipex.com/thread.xls

Hope it' helps H

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