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A Brag


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I've been messing around off and on for months now with an old 20 button Lachenal anglo, you know the type - plain mahogany ends, very basic. My brag is that I've successfully tuned the reeds without ruining any or indeed encountering any problems. There were three stages to this, the first overall tuning then two sessions of fine tuning to pick up the reeds that insist on reacting very differently on the tuning table than they do in the 'tina.

 

There is still an issue with this concertina that needs resolving, so I need to ask a question about endbolts and stripped threads. This cheapo model of Lachenal doesn't have the threaded plates you will generally find screwed into a rebate under the chamois gasket around the end of the bellows frame; indeed at first I assumed that the endbolts had just been allowed to cut their own thread into the wood of the bellows frame. An experienced repairer informed me that threaded plates were set in a slot part way down the frame presumably to save cost on rebating the plate and fixing it with screws.

 

Before I go any further can anyone describe how these are fixed in, and if the slot goes right through the frame from side to side (I've seen a few of these on ebay with suspicious bulges under the bellows end binding which might be caused by a seized plate revolving in its slot). If I can get to it and get it out without causing too much damage what do I replace it with? I believe that the tooling used to make these threads is no longer available, is there an available modern alternative? If I drill a hole of the right size in a piece of brass can I use the existing bolt to cut its own thread?

 

Perhaps it's time to be sensible and consign this one to the spare parts bin. <_<

 

Edited to correct grammatical errors pointed out by pedantic other half! :rolleyes:

Edited by tallship
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Before I go any further can anyone describe how these are fixed in

It's easy enough for you to see. Just pry up the chamois lining and you'll see a kerf from a rotary blade about halfway down in the bellows frame and the rectangular endbolt "nut" within it. Because the kerf was made from the inside it is much longer than on the outside of the bellows frame. Sometimes when there's a lot of stress on the nut (like the endbolt is frozen to it) it will turn, breaking some bellows frame wood and pushing the bellows leather covering a bit (making a bump there).

 

what do I replace it with?

If the nuts are in poor shape then the bolts probably are too (mangled heads, worn threads, bent shaft...) I suggest replacing all the bolts and nuts (nuts & bolts!). You could get a set of used ones in good shape (from some concertina repairers though only if they have a surplus at the time), or new ones to *match* the vintage ones (from people like Steve Dickinson)....

 

is there an available modern alternative?

... or you could get new ones very *similar* to vintage from current concertina makers (with modern threading size).

 

If I drill a hole of the right size in a piece of brass can I use the existing bolt to cut its own thread?

I doubt it as the hardness of both parts are similar and the bolt's threads are probably really worn.

 

-- Rich --

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Guest HallelujahAl!

Perhaps it's time to be sensible and consign this one to the spare parts bin

 

NO way! Just lift up the chamois gasket with a sharp implement - I use a dentists long pointy thing (cost a quid from the local market). Then gently prise out the threaded plate which will be right in the middle of the endframe. You'll find that any bit of bolt still stuck in the plate will in all probability unscrew back out again. When you replace the plate you will need to re-pack the plate with a small amount of wood filler (I make my own), and then re-cover the chamois. Often you'll find that the gasket will need padding out a little anyway in order to secure the reedpan and provide a good seal, so before gluing the chamois back down it may be possible to put a thin piece of card over the plate area which will give extra reinforcement to your repair. That's what I have done a few times now very successfully.

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Well it's been a busy old weekend which is why I've been slow to reply. Rich, thanks for all the info but as it turns out the problem wasn't as expected - nor was the slot in the bellows frame as you described (although that was exactly what I'd worked out in my head).

 

So here's what I found: The screw wouldn't tighten up because the plate 'nut' was missing entirely! The slot for the nut was only about a third of the way down the bellows frame and it was a straight mortice rather than a circular saw kerf; what's more the slot doesn't go all the way through the frame and is probably about 1/16" short of doing so.

 

I've got around the immediate problem of one of the chambers not sealing properly and choking a couple of reeds by moving a plate from another slot, this however doesn't address the general bellows air leakage problem caused by one fixing not working so I will need something to sort that out. I'll be in touch via PM or email to enquire about parts/prices etc. This thing is already into my ribs for more money than it's really worth so I'm not inclined to replace all of the fixings just for the sake of doing so ...

 

Pete.

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Well it's been a busy old weekend which is why I've been slow to reply. Rich, thanks for all the info but as it turns out the problem wasn't as expected - nor was the slot in the bellows frame as you described (although that was exactly what I'd worked out in my head).

 

So here's what I found: The screw wouldn't tighten up because the plate 'nut' was missing entirely! The slot for the nut was only about a third of the way down the bellows frame and it was a straight mortice rather than a circular saw kerf; what's more the slot doesn't go all the way through the frame and is probably about 1/16" short of doing so.

 

I've got around the immediate problem of one of the chambers not sealing properly and choking a couple of reeds by moving a plate from another slot, this however doesn't address the general bellows air leakage problem caused by one fixing not working so I will need something to sort that out. I'll be in touch via PM or email to enquire about parts/prices etc. This thing is already into my ribs for more money than it's really worth so I'm not inclined to replace all of the fixings just for the sake of doing so ...

 

Pete.

Pete, go and find a good hands-on clock mending book in the library, not a learned treatise but a hands-on grubby finger one; making/retrieving/bodging small nuts and bolts and mechanisms is meat and drink to those boys. I've got one somewhere but can't see it at the moment. I am sure that's where I'd look for a cheap and simple solution to a problem like this though.

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not a learned treatise but a hands-on grubby finger one;

Inspired thought! As a maintenance type I often have to come up with inventive solutions to the 'spare parts no longer available' conundrum. The tiny scale threw me. I immediately thought of model engineers and pretty much drew a blank; clock makers though, certainly worth investigating. Cheers mate. :)

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So here's what I found: The screw wouldn't tighten up because the plate 'nut' was missing entirely!

 

 

Pete, why make life harder than it already is? Simply send Dave Leese a bolt that isn't stripped, so that he can match the thread, and he'll be happy to sell you a threaded brass plate for a very modest sum. Be aware, though, that the threaded hole is rarely in the same place twice, so you need to make sure that everything lines up before you use Araldite to set the new plate in place.

Regards,

David

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So here's what I found: The screw wouldn't tighten up because the plate 'nut' was missing entirely!

Pete, why make life harder than it already is? Simply send Dave Leese a bolt that isn't stripped, so that he can match the thread, and he'll be happy to sell you a threaded brass plate for a very modest sum. Be aware, though, that the threaded hole is rarely in the same place twice, so you need to make sure that everything lines up before you use Araldite to set the new plate in place.

The plates should best be drilled and tapped in situ, as they were originally, and for such an inexpensive instrument I'd be tempted to use the old repairer's trick of utilising 7BA bolts as replacements, if you can find the taps and the bolts these days...

 

For that matter, I've seen late examples of the model with those "plates" made of fibreboard instead of brass before now, and had to replace every one of them. :(

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7BA taps, nuts, washers, all easy peasy but studding and bolts I can find none, so far that is. Everyone has been helpful and I've had several PMs with suggestions and advice, all very useful. I'll update in a few days if I've made any progress.

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  • 2 weeks later...

I would suggst that you get some brass :rolleyes: plate about the same thickness, and cut & file it so that it fits into the slot in the bellows. Then if you can get an endbolt and a tap to match, drill down through the endbolt hole, through the brass plate. Then cut the threads using your tap. You may have to remove the brass plate to do this easily, but the hole will be in the right position when you return it to the bellows frame. This is much easier than trying to fit a premade brass plate which will not have the hole in the exact place you need it to be.

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7BA taps, nuts, washers, all easy peasy but studding and bolts I can find none, so far that is. Everyone has been helpful and I've had several PMs with suggestions and advice, all very useful. I'll update in a few days if I've made any progress.

 

 

Try

www.ekp.supplies.btinternet.co.uk.

 

Geoff

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