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The thread on that screw is: .1656dia x 37tpi.
A classic "Enfield Special".
Not something they stock at the corner hardware shop; ditto the taps and dies.
And think of all the fun you can have shuffling the extra gears for your lathe gearbox to set it up for 37 TPI. Bear in mind that 37 TPI has a pitch of 0.686486486486mm, which is VERY close to 0.7mm. You can easily do that on a metric lathe. (M4 has a pitch of 0.7mm). Interestingly, the nominal diameter works out to 4.20624mm. Hmmmmm....
However, if you have a tame CNC shop nearby, and the like a challenge, you have the technology. The operator simply plugs in a CORRECTLY ground thread-form tool (NOT 60 degree), "tells' the machine what pitch and diameter are required at the correct stage and the machine does its thing. Think: infinitely variable ratio drives. Unless your friendly CNC shop is VERY tame, one screw will cost an arm and a leg. However, a hundred is just a couple of key-strokes away and wildly cheaper per unit. Keep a few for future projects and offer the rest for a reasonably sane price on the "for-sale" pages here. A win for everybody.
I've been down that track getting screws and other dinky bits made for the Francotte-actioned BSA Martini Cadet rifles. Still steadily selling off the "extras", which, in turn, has put me in contact with some interesting folk and THEIR projects / problems.
Last edited by Bruce_in_Oz; 03-20-2021 at 07:32 PM.
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03-20-2021 07:23 PM
# ADS
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Legacy Member
By the way, the P-14 dial-sight retaining screw has EXACTLY the same thread. Not too sure about overall length; someone out there will know to the last micron.
Cheers!
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Legacy Member
That's not the right thread. The Screw, Sight, Dial, Fixing uses a 0.181"x26 1/3 tpi Enfield thread. Using a gear calculator I was able to figure what will give me 26.347 tpi, which should be close enough, I just haven't gotten to making any yet as I don't need them right now and I do have plenty of other lathework on the table.
Last edited by WillSarchet; 03-20-2021 at 10:30 PM.
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Contributing Member
My recollection was that the bezel holding the pointer was a smaller thread to the thru bolt, basically a stepped hole.
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The tatty example was in a scrap forend & you can see how rusted in the screw was. It is still in, but when the day comes that I really need that specific plate badly enough I'll get it out. If the plate assembly is removed from the scrap woodwork there is a significant area of screw shank to hold in a vise. If you first give it a little wellie with a heat source a few times, the heating & cooling of it will rupture the bonds holding the rust. Then leave to soak in penetrant. Finally, using your hand, unscrew the plate from the screw (screw held tightly in vise).
It will come out, & you won't have to damage the screw to do it.
Last edited by Roger Payne; 03-21-2021 at 08:43 AM.
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Contributing Member
If you have the facilities to make a replica screw, that looks as it should externally. Would it no be easier to use a modern thread. It would make life easier and the thread is not visible when fitted.
So would it be a problem?
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Legacy Member
Originally Posted by
30Three
If you have the facilities to make a replica screw, that looks as it should externally. Would it no be easier to use a modern thread. It would make life easier and the thread is not visible when fitted.
So would it be a problem?
Only if you're also making a replica plate. Thread has to match the thread in the plate for it to work properly.
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If the original screw approximates to say, 3 BA, just make the replacement to that size & run a 3 BA tap down the thread inside the plate. Bob's your auntie!
Last edited by Roger Payne; 03-23-2021 at 08:13 AM.
Reason: clarity
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Advisory Panel
The question is whether you think it is stuck in the wood or the metal of the sight dial?
I would suspect the screw is well and truly rusted into the wood of the forened. Anyone who has seen old wooden objects that have rotted to the point of falling apart may have seen how fragments of the wood fibres remain bonded to the screw threads even after all the softer surrounding wood has rotted away. That's what you're up against.
A small hex impact driver might be useful, if there is enough of the screw slot left to use one. Something like this perhaps.
Last edited by Surpmil; 03-29-2021 at 03:23 AM.
Reason: Removed error
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If the forend is indeed scrap why not just remove the whole of the volley sight plate & screw assembly from the wood? You can get at the metalwork then. The volley plate screw is cheese headed, incidentally. The threads are likely rusted into the volley plate though there may well also be some adherence of the corroded shank of the screw in the wood.
Even if the forend is damaged further by the removal of the metal, it still has uses. I use such scrap pieces of woodwork as 'donors' for patches needed on otherwise serviceable woodwork. For example, the raised & rather thin piece of wood that often breaks off, located at the right rear of the forend between the charger guide recess & the very back end, can be carefully salvaged & grafted onto a needy piece of wood (glued & dowelled/brass wired)........pieces can be cut out of the area of the trigger guard recess & grafted on to another piece so as to make it usable again......& so on. Waste not want not!
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