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

[GreensandsParticipant @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.

[duncan webster 1Participant @duncanwebster1]

It’s for securing whim whams down a treacle mine.

More seriously it’s a shoulder bolt for something to pivot on

[Nicholas FarrParticipant @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.

[GreensandsParticipant @greensands]

I recall a fabled treacle mine many years ago in the Surrey village of Chobham!

[Michael GilliganParticipant @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.

[Nicholas Farr]

On Nicholas Farr Said:

…the threaded part would probably screw intro a threaded hole up to the shoulder, and the nut would lock it to stop it unscrewing.

That is a good observation and would account for the excessive threaded length compared to the standard metric offerings linked to above.

It might be useful to measure the length of the plain shank to see how close it is to a nominal dimension (the pivoting thing would need some slight side clearance when the shoulder where the threads run out touches down).

A rub with a hardness tester might be instructive – standard ones as above RS link are tough (I broke an M9 die trying to make a replacement screw for a Bosch multitool from one).

[Nigel Graham 2Participant @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?

[ChrisLHParticipant @chrislh]

Apart from features already mentioned the hexagons are remarkable for their large axial thickness. Possibly pre-WW2.

[old martParticipant @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.

[Chris CrewParticipant @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’?

[BazyleParticipant @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.

[cedric 1Participant @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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