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Lachenal Screw Threads


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I had my Lachenal English Concertina apart this afternoon and measured the threads of the screws holding the action box to the frame. The closest match is around 3/32 by 38 threads per inch. I think the old Whitworth standard for 3/32 was 48 tpi, so I don't think these are Whitworth screws. Are they some sort of standard screw are are they idiosyncratic to Lachenals? I'm not having any problems with the screws, I just measured them out of curiosity.

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I had my Lachenal English Concertina apart this afternoon and measured the threads of the screws holding the action box to the frame. The closest match is around 3/32 by 38 threads per inch. I think the old Whitworth standard for 3/32 was 48 tpi, so I don't think these are Whitworth screws. Are they some sort of standard screw are are they idiosyncratic to Lachenals? I'm not having any problems with the screws, I just measured them out of curiosity.

As far as I know, they're standard for concertinas by all the old makers, but only for concertinas.

 

I.e., they're not part of a broader industrial standard, new or old.

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As far as I know, they're standard for concertinas by all the old makers, but only for concertinas.

 

I.e., they're not part of a broader industrial standard, new or old.

 

Ah, if only that were so! As it is, there are many, many variations in both thread pitch and diameter - and that's before you start to consider length and head shape.

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I would assume that as concertinas were (generally) around before mass adoption of most thread standards that they are more than likely individual companies choice.

This link gives a comparison of all sorts of uk thread standards.http://www.britishfasteners.com/threads/index.html

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I'm a little puzzled by this question. The screws we're talking about are wood screws, aren't they? They pass through a hole in the sound board and grip the wood attached to the end plate, not a sunken nut, as the end bolts do. So why does it matter what the particular measurements of the thread are? Each screw will find its way to grip the wood until the wood is so completely bored out that none will. What am I missing?

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I'm a little puzzled by this question. The screws we're talking about are wood screws, aren't they? They pass through a hole in the sound board and grip the wood attached to the end plate, not a sunken nut, as the end bolts do. So why does it matter what the particular measurements of the thread are? Each screw will find its way to grip the wood until the wood is so completely bored out that none will. What am I missing?

 

 

 

 

RWL does say " holding the Action box to the frame".... frame of the bellows ? So, he is talking about the End Bolts... and besides, Wood Screws are not measured in this way at all; usually stipulated by a designation number ,length and head type.

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Yes, I should have used the term end bolts when I posted the first message. That would have been the correct term for the concertina. They're really just a long machine screw though. I"m not sure if that difference in terminology has some historical reason, or whether it's a difference between US English and UK English.

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  • 2 weeks later...

For what it is worth: In my research on the Lachenal family and businesses, I have been in contact with descendents of the Lachenal family. Though undocumented, it has been handed down through the family that Lachenal purchased screws from Nettlefold & Chamberlain and purchased bolts from the Patent Nut and Bolt Co. These companies were later folded into the formation of GKN (Guest, Keen & Nettlefold), along with other companies. An 1868 advertisement for the Patent Nut and Bolt Co. is shown in the attachement.

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