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Lop-Sided Bellows


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#1 DavePraties

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Posted 13 September 2017 - 04:45 AM

An interesting problem has just come to light, and I would welcome any advice.

The restoration of one of my large Lachenal MacCann duets necessitates replacing the entire outer moulding which holds the ends and fixes them to the action board. I decided to do this, as the existing woodwork, and indeed metal ends, are very clearly not original, and are very crudely made, and spoil the overall appearance quite a lot. I copied the moulding from another instrument, complex ebony/teak with lots of shaping and rebating. No problems though, until I began to make the former on which to glue it up into a frame, and found that the bellows are quite badly non-symmetrical. That is to say, each end is not a perfect hexagon, but has possibly moved out of kilter during its life, or probably during its poor repair. The bellows seem quite rigid though, are in fine condition and function very well.

My inclination is running in the direction of building the ends to fit the bellows whatever their shape, rather than trying to straighten them up with the possible consequence of breaking glue lines and causing damage to the leather-work. What do the experts think? Any advice/musings welcome.



#2 malcolm clapp

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Posted 13 September 2017 - 05:23 AM

It isn't really clear from your post (at least to me) whether it is the bellows and/or the bellows frames that are non-symmetrical. I assume the latter.

 

If the bellows frames are rigid and the reedpans fit inside them snugly, I would suggest that using them as your template for the end rail geometry would save you a lot of  work as you suggest in your last paragraph. However, if they do lack rigidity, they will need to be re-glued, and perhaps better to align their geometry to that of the ends (and/or the reedpans) when doing so.

 

(If it is just the bellows itself which is causing concern, I wouldn't worry overly much, though a new set of bellows will probably be the only solution, but if it is as functional as you state, then replacement might be a bit overkill at this juncture. Best wait till a few leaks and a bit of wear becomes apparent....)

 

My 10c worth....



#3 DavePraties

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Posted 13 September 2017 - 07:22 AM

Hello Malcolm, Thanks for your reply. Untill you mentioned it, I stupidly hadn't thought about the reedpans. They fit fine and snugly, so a pointer, I guess, to the fact that the instrument has always been that shape. It is the bellows, complete with  frames which are non-symetrical, and hence I guess, the whole instrument. It is not bad enough to be noticeable, just took me by surprise when I measured and drew the ends prior to reconstruction of the outer woodwork. This instrument has riveted action, and very good reeds, so I assume it was an up-market Lachenal. Were these instruments built around a mould, or freehand, do we know? Is lop-sidedness unusual?

Regards, Dave.



#4 Theo

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Posted 13 September 2017 - 02:01 PM

It's common for instruments to be not exactly symmetrical. One post construction causecis shrinkage of the reed pan and action board which is naturally greater across the grain than along the grain.

#5 DavePraties

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Posted 14 September 2017 - 01:55 PM

Never thought of the reed pan deforming. I should have done, having seen plenty of age related shrinkage in wooden components. I'm certainly not going to try to correct that. I will build the ends to suit the bellows.



#6 d.elliott

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Posted 14 September 2017 - 02:36 PM

The key to all this is the fit of the reed pans into the end frames, remembering that shrinkage sometimes necessitates re-packing the chamois gaskets in the inner faces of the bellows frames. Everything else can be derived from the bellows frame geometry.

 

So:

  • don't mess with the end frames,
  • ensure the reed pans are a snug fit in the bellows frame gaskets.
  • check the reed pan support blocks to ensure that the chamber gaskets are flush if not a tad proud of the bellows frame end face gaskets
  • line up the pad board casings sections to make sure that the end bolts line up exactly with the bellows frame nuts
  • same for the casing around the finger or end plate
  • and breathe.......

Dave


Edited by d.elliott, 14 September 2017 - 02:37 PM.


#7 DavePraties

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Posted 14 September 2017 - 03:20 PM

Dave, This is great mind-focussing advice. Thanks very much for it.

Whilst I'm here, should I decide to replace the crude, non-original alluminium ends with Nickel silver ones, do we know of anyone who would laser cut them if I produced a CAD drawing? Should I roll  the raised part around the buttons first, or after the cutting?

Dave



#8 Bill Crossland

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Posted Today, 06:39 AM

Hi Dave

 

I make and fit new laser cut ends in both wood and nickel silver, but could only offer flat ends - I'm not equipped to make raised ends as on your instrument....






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