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Lachenal spring problem (English Concertina)


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This is probably a question that has been asked before, but I couldn't find the answer.  Sorry. 

 

The left-hand middle B on my Ediophone has started to sound on the "push" after about half an hour of playing after I have put the concertina back together after the latest attempted repair. The button is ever-so-slightly depressed compared to those around it when it is at rest. 

 

I have replaced the spring, but that has not solved the problem.

I have tried gently expanding the new spring to  force the finger end up and provide more pressure on the pad, but that didn't solve the problem. 

 

Its an awkward lever, because it is bent round the recently-replaced support post.  I'm reasonably certain that the lever is not fouling on the post. The position of the post is such that the lever cant be easily removed from the fulcrum (e.g. to try bending it in a vice)

 

The problem was there before the post was replaced but has now got worse. 

 

The pad is OK. 

 

Should I

a) try putting the spring base into the wood slightly closer to the button (it is possible that putting it into the old-spring hole did not give it a firm enough foundation so the base is moving )?

b) maybe the replacement spring was a dud ? (see below)

c) add another spring to the lever ? I think i could fit one in, and someone has previously done that to another lever in the instrument)

 

I have now used up all my repair kit springs, so I would like to buy another half-dozen.  Please suggest someone who is selling them in the UK. 

 

Thanks

Gail

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I would put money on the lever or the spring, or even the button rubbing against something when the end is on, as the button is pushed slightly to one side. The replacement post is a big clue. I have just repaired two concertinas with the similar issues. I had to shave the post on one, and scrape paint from a button on the other.

stronger springs just mask the real problem.

Concertina Spares sells new springs.

 

Good luck

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It may be that the felt button bushing a causing this...... friction! Remove the end of the instrument. Push a suitably-sized pencil into the hole with a twisting motion, Also using a soft lead pencil rub the lead onto the inner surface of the felt bushing, reducing the friction. Let me know how this works for you.

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Hi there Gail,

 

I have seen an incident of this phenomenon where two pads were too close together and began to get in each other's path. If one of the affected levers is rather long, there is lateral play that may cause the two pads to get in touch with each other.

 

What you can do here is take some fine colored powder, lightly dust the pad of the affected button all the way around and check to see if the powder has died off to one of the adjacent pads.

 

The fix the person who had this problem applied was to take a scalpel and cut off a very tiny part of the pad. Of course this is a fairly invasive operation, and one needs to take care not to take off too much material. The probably preferrable option in this case would be to replace the pad with a smaller one that still seals the hole correctly, or correct (eg bend back) the lever.

 

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A  cranked , or  convoluted path,  lever combined  with  a  non riveted  action,  as in a Lachenal,  can  result  in   sideways  wear  at  the pivot  and  the  lever  can  start to  lean  to  one side  under the  force  of the  spring.  You could  try  mounting the spring on the other  side of the lever  but otherwise some  remedial work  might  be  needed.

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I've come across this problem a number of times where the cranked lever wears unevenly as described by Geoff.  The actual wear takes place in a tiny area on the side of the lever where it passes through the support post, and on the inner surface of the window in the support post.  It's often almost impossible to see the wear unless you remove the lever and the post and examine them through a lens.  You can usually see the result of the wear because the lever will appear tilted over to one side.  Comparison with nearby straight levers is helpful here.  When  one replaces a Lachenal support post the lever should be replaced at the same time because if one is worn the other will be too.

 

This cranked lever is a weak point in the Lachenal EC design.  The best solution in the long term is to replace the lever and post with a riveted lever and post.  These are better able to handle the sideways forces generated by the cranked lever.  They will still wear but should have a longer life than the original Lachenal design.

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Thank you. Some good ideas to investigate here.

 

 

It's not the felt bush though because it is a metal-ended instrurment and has a sort of integral thickening plate that does that job and there is no felt - I should have said this at the beginning

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I had this problem with a Crabb duet I owned. @alex_holden gave me great advice. Take the end off and remove the button. Put the end back on. Now look straight through the bushed hole to the peg hole. Is the lever directly above it? If not, gently bend the lever with a small pair of pliers so that it is. (Take the end off first!) It worked for me.

 

LJ

 

Afterthought: The Crabb's levers were riveted. I don't know if this solution will work for hooked levers.

Edited by Little John
Afterthought
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Edeophones wear both the post and lever, especially on cranked levers. A solution I have employed is to machine a new lever and make it deeper than the old one. This means it bears on the side of the slot in the post at a point lower than the old lever and consequently it spans the worn spot. It should last as long as the first one did. Best solution, as Theo says, is to replace the post and lever with one of a better design. 

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What I know as Cranked Arm Syndrome, as stated before, occurring on non-linear arms where they are not a riveted pivot design. Lachenal instruments often have this feature and Edeophones have it in multiplicity. The arm and the pivot post aperture both wear, resulting in the lifting action being on a slant. i.e. the pad does not lift vertically. the key is often leaning a little as well and the key height is often a little lower than those other keys around it. Initially I tried removing the pivot post and turning it round which put the worn part of the arm against unworn areas of the aperture, halving the problem, a quick way of improving a less than happy situation, but it buys time.

 

The only way (for those who are not blessed with a machine shop) is to get a reclaimed pivot post and a long arm from a scrapper. measuring from the cusp of the pivot swan neck, form a new arm using the old as a pattern. 

 

I was once asked by a famous concertina restorer and now manufacturer of traditional concertinas: which would I choose (technically), Lachenal or Wheatstone and why. I chose Wheatstone for this very reason. He nodded and walked away.

 

Gail, you know how to contact me, give me a call and lets see what can be done

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I had the cranked arm, worn pivot problem on my extended treble New Model. It was the longest, most convoluted lever in the box. I understand that long levers with lots of kinks are most susceptible to this problem. After much fooling around I had that action replaced with a riveted one and have had no further problems.

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