What might have been the original use of this very nicely made 3″ Bolt?

This topic has 11 replies, 11 voices, and was last updated 27 January 2026 at 17:32 by cedric 1.

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27 January 2026 at 11:59 #834484
Greensands
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@greensands
I picked up this innocent looking bolt from an exhibition some years ago and have been intrigued ever since on what it’s possible use may possibly have been. It mics up as a 3” x 5/8” 11tpi UNC bolt, the shank section measuring ¾” in diameter but the most fascinating feature is the remarkably high quality of finish put into its manufacture, far exceeding what you would normally expect to see from a standard bolt of this size. This raises the interesting question as to what possible use it may have been intended for , possibly in nuclear engineering or some advanced forms of engineering? In the mean time it lurks on my workshop shelf looking for a possible application.
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27 January 2026 at 12:06 #834494
duncan webster 1
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@duncanwebster1
It’s for securing whim whams down a treacle mine.

More seriously it’s a shoulder bolt for something to pivot on
27 January 2026 at 12:37 #834499
Nicholas Farr
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@nicholasfarr14254
Hi, Duncan is correct, and the threaded part would probably screw intro a threaded hole up to the shoulder, and the nut would lock it to stop it unscrewing.

Regards Nick.
27 January 2026 at 12:51 #834500
Greensands
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@greensands
I recall a fabled treacle mine many years ago in the Surrey village of Chobham!
27 January 2026 at 13:03 #834501
Michael Gilligan
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@michaelgilligan61133
There’s a fighting chance that P.B. stands for Pivot Bolt

1874 suggests that it might be one of many

… or it could simply be a part number.

MichaelG.
27 January 2026 at 13:48 #834521
DC31k
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@dc31k
27 January 2026 at 16:23 #834553
Nigel Graham 2
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@nigelgraham2
Given the very abrupt change from shoulder to head, and that not chamfered, perhaps it was a fitted bolt rather than apivit botls; i.e, as a dowel between two static components?
27 January 2026 at 16:54 #834555
ChrisLH
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@chrislh
Apart from features already mentioned the hexagons are remarkable for their large axial thickness. Possibly pre-WW2.
27 January 2026 at 16:55 #834556
old mart
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@oldmart
I would expect that the bolt was made from hexagon barstock and not mass produced. That would explain the higher quality.

Ithought the treacle mines were in Knotty Ash.
27 January 2026 at 17:07 #834558
Chris Crew
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@chriscrew66644
When a person who had no experience of lathe work joined our club, I invited him to come and have a ‘play’ on my Colchester. As an exercise, under my supervision, he made a bolt very much like this as an exercise. So maybe this is an ‘apprentice piece’?
27 January 2026 at 17:19 #834561
Bazyle
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@bazyle
Every reasonable sized machine like a loom or printer has a dozen such bolts – only screwcut the bit you need to saves time to make aswell as aligning parts. The letters and number on it are hand spark engraved so probably by the fitter who was taking something apart to indicate what machine serial no it belonged to … that never got rebuilt.
27 January 2026 at 17:32 #834565
cedric 1
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@cedric
Common a garden shoulder bolt. A million uses in industry as mentioned, pivoting, locating, plus thing like retaining and guiding stripper plates on press tooling and so on. Impossible to guess what this particular one was used for.
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