Can anyone I.D. a bolt via size? - UK Vintage Radio Repair and Restoration Discussion Forum

g4aaw pete · 23rd Jan 2018, 11:21 pm

Apologies if this is thought to be off-topic for this forum.

I've lost a clamping bolt from a camera tripod. Bought in 1980, it might be considered 'vintage'.
Have found a hex head bolt that fits the threaded hole, but can't determine the type.
Dimensions are:

20 T.P.I.
Hex head 13.25 mm across flats
Thread diameter 7.775 mm

Can any of our engineering-biased members identify this size.

Regards
Pete

Alistair D · 23rd Jan 2018, 11:54 pm

This is my go to site whenever I need to identify a bolt.

https://mdmetric.com/thddata.htm

Al

Station X · 24th Jan 2018, 12:02 am

Could be M8 which is 1.25mm pitch.

Radio Wrangler · 24th Jan 2018, 12:05 am

1/4 inch whitworth is 20 tpi, but the clearance hole is 6.5mm so that's too small. Quarter whit is one of the standard tripod bush threads.

BSF 3/8 inch is 20 tpi but the ouverall diameter is 9.7mm so it's not that either

BA... nope 0BA is smaller and finer pitched

BSP doesn't hit 20 tpi 1/4 bsp is closest, but too large in diameter

Si Metric 8mm has pitch at 1.25mm which is 20.32 tpi and the outer diameter is about 7.7 to 7.9mm.

If your 20tpi isn't exact, then M8 looks like your fella.

There are extensive tables here: http://historicmotorcycle.org.au/ima...ead_Tables.pdf

David

Station X · 24th Jan 2018, 12:11 am

Only problem with M8, which is what I think it is, is that it should have a 13mm AF head. There'll be some tolerance on this though.

g4aaw pete · 24th Jan 2018, 12:32 am

Many thanks for your responses.

The tripod was made by Vivitar (model 914), so I'd have thought the threads would be metric.

Indeed, a 13 mm spanner slightly too small.
I have a nut for the bolt being measured, so I'll see if an M8 bolt will fit at one of the D.I.Y. outlets.

Regards
Pete

Ed_Dinning · 24th Jan 2018, 12:39 am

Hi Gents, don't forget the UNF/ UNC series, US origin and used in a lot of automotive applications.
They are close to both Whit and M8 but bind up due to thread forms and slight pitch differences after about 1 turn.

Ed

Station X · 24th Jan 2018, 1:04 am

None of the 20 TPI variants in the Unified series fit the rest of the spec though.

emeritus · 24th Jan 2018, 2:15 am

That's a very unusual bolt you have. The head size and diameter are a good match for 5/16 Whit , but the pitch is wrong. It could be a special.

I have sometimes found stuff that has threads that do not correspond to any of the threads found in my 1970's edition of "Machinery's guide to world screws". For example, traditional Sheffield-manufactured Bailey cast iron planes use a special thread (Sheffield plane thread) that is much coarser than Whitworth. Axminster Tools is the only place I have found any mention of its existence. They used to supply a length of plane thread studding with their replacement wooden plane handles. A work colleague found that the studding supplied was just too short for his plane and he had to get a contact in a workshop at Marconi to make him up a length specially on a lathe.

My 1940 copy of Machinery's handbook has data for the threads that were used in the US before the Unified system became standardised. It does list under the old "Standard ASME thread" both a No. 18 bolt, 0.294" (~7.4mm) , and a No.20 bolt, 0.32" (~7.95mm) with 20TPI . I have in the past found that new self-assembly furniture made in Taiwan had bolts conforming to the pre-war obsolete US standard, the pitches of which are much coarser than the present Whitworth, UNC and Metric coarse threads : possibly they bought up the old machine tools cheaply?

Boater Sam · 24th Jan 2018, 2:27 am

If it was intended to be hand tightened, maybe they did not concern themselves with the head size too much. Most of my cameras have had metric threads.
Raleigh cycles used there own odd thread TPI as well, finer than standard bike thread.

Station X · 24th Jan 2018, 7:46 am

If the original bolt was intended to be tightened by hand I think it would have had a large diameter knurled head. The OP described a bolt which fitted the thread, not the original.

Boater Sam · 24th Jan 2018, 8:14 am

Oh, you are so right Graham. I have a knurled head too.

turretslug · 24th Jan 2018, 11:02 am

Japanese industry seems to like to break convention sometimes with metric bolts, e.g. M8 bolts having either 12 or 14mm A/F heads depending whether space was tight or item secured was of soft alloy- perhaps the 13.25mm measured is a slack 14mm?

vidjoman · 24th Jan 2018, 2:52 pm

A quick look at Wikipedia will give you all the sizes. Look for “camera tripod Bush sizes”.

Boater Sam · 24th Jan 2018, 3:26 pm

This has been raised before elsewhere, its a quarter X 20 thread, not metric according to this thread
http://photography-on-the.net/forum/...d.php?t=302089
All "modern" cameras are this thread he says with fingers crossed and Knurled head in a bag.

Station X · 24th Jan 2018, 4:01 pm

I don't doubt it Sam, but 1/4" is 6.35mm which is smaller than the 7.775mm reported by the OP.

barrymagrec · 24th Jan 2018, 4:13 pm

I assumed that a clamping bolt was part of the tripod, not the bolt that goes into the camera......

Camera threads are almost always 1/4" in my experience, apart from some pre war continental cameras such as Leica which are 3/8".

I think that it is unimportant whether they are Whitworth or UNC threads since the camera socket is very short.

ColinTheAmpMan1 · 24th Jan 2018, 4:14 pm

Quote:

Originally Posted by emeritus

"Machinery's guide to world screws"...

Am I the only one to have found this scatological? Then again, I am known to have a dirty mind...
Colin.

Station X · 24th Jan 2018, 4:20 pm

If the clamping screw's thread is M8, something like this would do the job:-

https://www.ebay.co.uk/i/12171422932...4960578&crdt=0

Herald1360 · 24th Jan 2018, 4:21 pm

I have a possible answer (not to the thread size, but the confusion over 1/4 whit or not).

In the attached picture is the head of my tripod, with the clamping screw removed. The 1/4" threaded bit is at the top, below it is a larger threaded bit used to retain the the screw in the slot as a captive bolt arrangement. The thread for that can be seen in the end of the slot.

Whilst the 1/4" thread is standard for the bottom of a camera, presumably the retaining threaded collar bit is whatever the tripod maker picked. So probably the most likely of the suggestions is M8 given the date of the tripod.

Edit: Having seen Graham's post, the clamping screw in the link could well be made into a replica of mine with a bit of cunning lathe work!

What mine actually is, I've no idea. The tripod dates from the '50s.

23rd Jan 2018, 11:21 pm	#1
g4aaw pete Heptode Join Date: Jan 2008 Location: Birchington Kent, UK. Posts: 596	Can anyone I.D. a bolt via size? Apologies if this is thought to be off-topic for this forum. I've lost a clamping bolt from a camera tripod. Bought in 1980, it might be considered 'vintage'. Have found a hex head bolt that fits the threaded hole, but can't determine the type. Dimensions are: 20 T.P.I. Hex head 13.25 mm across flats Thread diameter 7.775 mm Can any of our engineering-biased members identify this size. Regards Pete

23rd Jan 2018, 11:54 pm	#2
Alistair D Nonode Join Date: Jan 2010 Location: Edinburgh, UK. Posts: 2,008	Re: Can anyone I.D. a bolt via size? This is my go to site whenever I need to identify a bolt. https://mdmetric.com/thddata.htm Al __________________ I won't tell you how I discovered that.

24th Jan 2018, 12:02 am	#3
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Can anyone I.D. a bolt via size? Could be M8 which is 1.25mm pitch. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

24th Jan 2018, 12:05 am	#4
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,874	Re: Can anyone I.D. a bolt via size? 1/4 inch whitworth is 20 tpi, but the clearance hole is 6.5mm so that's too small. Quarter whit is one of the standard tripod bush threads. BSF 3/8 inch is 20 tpi but the ouverall diameter is 9.7mm so it's not that either BA... nope 0BA is smaller and finer pitched BSP doesn't hit 20 tpi 1/4 bsp is closest, but too large in diameter Si Metric 8mm has pitch at 1.25mm which is 20.32 tpi and the outer diameter is about 7.7 to 7.9mm. If your 20tpi isn't exact, then M8 looks like your fella. There are extensive tables here: http://historicmotorcycle.org.au/ima...ead_Tables.pdf David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

24th Jan 2018, 12:11 am	#5
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Can anyone I.D. a bolt via size? Only problem with M8, which is what I think it is, is that it should have a 13mm AF head. There'll be some tolerance on this though. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

24th Jan 2018, 12:32 am	#6
g4aaw pete Heptode Join Date: Jan 2008 Location: Birchington Kent, UK. Posts: 596	Re: Can anyone I.D. a bolt via size? Many thanks for your responses. The tripod was made by Vivitar (model 914), so I'd have thought the threads would be metric. Indeed, a 13 mm spanner slightly too small. I have a nut for the bolt being measured, so I'll see if an M8 bolt will fit at one of the D.I.Y. outlets. Regards Pete Last edited by g4aaw pete; 24th Jan 2018 at 12:36 am. Reason: Extra info

24th Jan 2018, 12:39 am	#7
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Can anyone I.D. a bolt via size? Hi Gents, don't forget the UNF/ UNC series, US origin and used in a lot of automotive applications. They are close to both Whit and M8 but bind up due to thread forms and slight pitch differences after about 1 turn. Ed

24th Jan 2018, 1:04 am	#8
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Can anyone I.D. a bolt via size? None of the 20 TPI variants in the Unified series fit the rest of the spec though. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

24th Jan 2018, 2:15 am	#9
emeritus Dekatron Join Date: Jan 2012 Location: Brentwood, Essex, UK. Posts: 5,339	Re: Can anyone I.D. a bolt via size? That's a very unusual bolt you have. The head size and diameter are a good match for 5/16 Whit , but the pitch is wrong. It could be a special. I have sometimes found stuff that has threads that do not correspond to any of the threads found in my 1970's edition of "Machinery's guide to world screws". For example, traditional Sheffield-manufactured Bailey cast iron planes use a special thread (Sheffield plane thread) that is much coarser than Whitworth. Axminster Tools is the only place I have found any mention of its existence. They used to supply a length of plane thread studding with their replacement wooden plane handles. A work colleague found that the studding supplied was just too short for his plane and he had to get a contact in a workshop at Marconi to make him up a length specially on a lathe. My 1940 copy of Machinery's handbook has data for the threads that were used in the US before the Unified system became standardised. It does list under the old "Standard ASME thread" both a No. 18 bolt, 0.294" (~7.4mm) , and a No.20 bolt, 0.32" (~7.95mm) with 20TPI . I have in the past found that new self-assembly furniture made in Taiwan had bolts conforming to the pre-war obsolete US standard, the pitches of which are much coarser than the present Whitworth, UNC and Metric coarse threads : possibly they bought up the old machine tools cheaply?

24th Jan 2018, 2:27 am	#10
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Can anyone I.D. a bolt via size? If it was intended to be hand tightened, maybe they did not concern themselves with the head size too much. Most of my cameras have had metric threads. Raleigh cycles used there own odd thread TPI as well, finer than standard bike thread.

24th Jan 2018, 7:46 am	#11
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Can anyone I.D. a bolt via size? If the original bolt was intended to be tightened by hand I think it would have had a large diameter knurled head. The OP described a bolt which fitted the thread, not the original. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

24th Jan 2018, 8:14 am	#12
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Can anyone I.D. a bolt via size? Oh, you are so right Graham. I have a knurled head too.

24th Jan 2018, 11:02 am	#13
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,395	Re: Can anyone I.D. a bolt via size? Japanese industry seems to like to break convention sometimes with metric bolts, e.g. M8 bolts having either 12 or 14mm A/F heads depending whether space was tight or item secured was of soft alloy- perhaps the 13.25mm measured is a slack 14mm?

24th Jan 2018, 2:52 pm	#14
vidjoman Dekatron Join Date: Jun 2013 Location: East Sussex, UK. Posts: 3,326	Re: Can anyone I.D. a bolt via size? A quick look at Wikipedia will give you all the sizes. Look for “camera tripod Bush sizes”.

24th Jan 2018, 3:26 pm	#15
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Can anyone I.D. a bolt via size? This has been raised before elsewhere, its a quarter X 20 thread, not metric according to this thread http://photography-on-the.net/forum/...d.php?t=302089 All "modern" cameras are this thread he says with fingers crossed and Knurled head in a bag.

24th Jan 2018, 4:01 pm	#16
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Can anyone I.D. a bolt via size? I don't doubt it Sam, but 1/4" is 6.35mm which is smaller than the 7.775mm reported by the OP. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

24th Jan 2018, 4:13 pm	#17
barrymagrec Octode Join Date: Dec 2017 Location: Morden, Surrey, UK. Posts: 1,558	Re: Can anyone I.D. a bolt via size? I assumed that a clamping bolt was part of the tripod, not the bolt that goes into the camera...... Camera threads are almost always 1/4" in my experience, apart from some pre war continental cameras such as Leica which are 3/8". I think that it is unimportant whether they are Whitworth or UNC threads since the camera socket is very short.

24th Jan 2018, 4:20 pm	#19
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Can anyone I.D. a bolt via size? If the clamping screw's thread is M8, something like this would do the job:- https://www.ebay.co.uk/i/12171422932...4960578&crdt=0 __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

24th Jan 2018, 4:21 pm	#20
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Can anyone I.D. a bolt via size? I have a possible answer (not to the thread size, but the confusion over 1/4 whit or not). In the attached picture is the head of my tripod, with the clamping screw removed. The 1/4" threaded bit is at the top, below it is a larger threaded bit used to retain the the screw in the slot as a captive bolt arrangement. The thread for that can be seen in the end of the slot. Whilst the 1/4" thread is standard for the bottom of a camera, presumably the retaining threaded collar bit is whatever the tripod maker picked. So probably the most likely of the suggestions is M8 given the date of the tripod. Edit: Having seen Graham's post, the clamping screw in the link could well be made into a replica of mine with a bit of cunning lathe work! What mine actually is, I've no idea. The tripod dates from the '50s. Attached Thumbnails __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O