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Bellows making - joining the 'peaks'


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I'm part way through making a set of bellows using Bob Tedrow's method, and have reached a point where I need some advice, please.

The bellows is mounted in a jig and  I am at the point of putting the cotton binding to the top of the folds before starting on the leather.

However, a question springs to mind -the two ends of the tube forming the bellows are currently not joined, and can move. All the other five 'peaks' are joined. Do I need to join the two ends first to provide a stable bellows?  Hopefully you get my drift.

If I were using the traditional approach, would  each of the sections of card be joined together, and if so how?

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The outer cloth hinge goes all the way around (the ends butting up in the middle of a side). That holds the sides together while you put the gussets on, then the leather binding will strengthen it further.

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Alex, thanks for your reply.

 

I just thought you may need to make sure the last  peak was secure (as the remaining 5 are) before putting the cloth on. I can rest easy then, because this was proving very tricky.

 

I will go ahead and fix the cloth

 

Regards

Rod

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  • 2 weeks later...
  • 1 month later...
Posted (edited)

I have completed installing the gussets, but now have another issue.

 

I have taken the bellows out of the jig, and find that they are now acting like a spring. The bellows were compressed before going into the jig , and closed pretty flat. Now, after exercising them a bit I find they only close about half way unless I exert more force that would be expected during normal use. When I do close them, they spring back. I have not fitted the end or top runs yet. I have attached a picture of the bellows in their relaxed state. ?

 

All the other instruments I have close under their own weight, so there is obviously something amiss.

 

Could I do anything to relax the bellows, or are they lost cause? If so I am happy to put it down to experience and start again. I want to get them right before refitting the reed pans and action boxes.

 

Many thanks466826303_IMG_20651.thumb.JPG.cb6b3a673bf8d2c7a0e87d28badec32e.JPG

 

IMG_2066[1].JPG

Edited by Rod Pearce
photo added
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I found the same thing happened after I did some major repairs and new top runs on a previously very flat bellows.  I made a pair of hexagonal blocks that are small enough to just clear the the reed pan blocks when inserted into the ends of the bellows, and used a bar clamp to compress bellows.  After about a week it was much flatter, although still with some spring to it.

 I note that the bellows on my newly built Carroll still spring partly open when it is taken out of its case, so some springiness is to be expected I think.

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Compression should help, however looking at the inside it appears the angle of the vee between two adjacent cards is quite small; that space between the cards is needed for the gussets to fold into when the bellows close. On mine I have about 14º clearance between adjacent cards when the bellows are fully closed.

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Alex

 

You are right about the size of the angle between the cards.I have been following Bob Tedrow's method, which suggests an angle of 55 degrees for the sides, so assuming the angle of each corner is 60 degrees. I make it that the angle between adjacent cards is 10 degrees (2 x 5 degrees).

 

Two other possible factors are

- the lambskin hinge in the valleys fitted when the cards are still flat, skived to 0.5 mm, possible a little thick?

- the card itself is rising-museum-board-4ply-16x20 @ 1.52mm, again possibly too thick.

Bill

 

I too have made some of those hexagonal blocks from a previous job, so I can try your suggestion. All the compression so far has been from outside the end frames

 

Then continue to conclusion and see what I end up with. 

 

Thanks for your replies

 

Rod

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Give the compression a try and see what happens after they have been clamped tight for a few days. It's normal to get some springiness until they are broken in. Something else that can make them reluctant to fully close is if the edges of the gussets aren't skived thin enough, particularly the bit where they fold flat at the bottom of the valley.

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I am considering removing the end frames before compressing. Some of the joints have burst in the previous compressions, so repairs seem to be in order. I should be able to get better access to the troublesome parts with the frames out of the way.

 

As for the gussets, they were skived down from 0.5mm to nothing at the edges, Perhaps I used too much , or too thick, hide glue.

 

So much to learn!

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Did I read this correctly that the problem did not show until you fitted the gussets? Meaning that with just the linen liners glued on, the bellows closed fine?

 

To me it looks as if the folds somewhat bulge. On the attached detailed picture, there is one side that appears to have a fairly straight edge (the one marked red), whereas the other ones sort of look like the linen liner was glued on too tightly, thus forcing the two cartons they join into a curved shape.

 

Yet I wouldn't have an explanation why this didn't show until the gussets were fitted. Do you have a picture taken before that? Did the outer edges of the folds look like they do on this picture as well?

 

bellows1.JPG

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RAc

 

Unfortunately I didn't take pictures between fitting the bindings and the gussets.

 

However, I have taken on board your suggestion that the bindings may be contributing to the problem. So I have tried an approach to relax them a bit. I have moistened them all slightly with a damp sponge (they are not wet) to introduce a little moisture, and put the bellows back under compression After a couple of hours I removed them, and found that the amount of spring back has reduced significantly. I will re-compress and leave the whole assembly to dry fully, then see what I have. Fingers crossed.

 

Regards

Rod

 

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Great, please keep us informed about the progress! Hopefully "swarm intelligence" will help resolve the issue!

 

 

2nd edit: I'm probably paranoid, but I suggest you put some isolation material (baking sheets or the like) in between the folds during compression. I've read somewhere that one of the things you don't want to happen is the liners glue together when they are moist (which also applies to the glue below them) and touch the neighbor liner...

Edited by RAc
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Don’t underestimate the time needed in compression. I find a couple of days way too short. A month makes more sense, take them out and stretch them every few days. And after they are in service make sure they go back in a good box or have some form of compression when not being used for a year or so. 

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Chris

 

Thank you for this nugget! I had anticipated a couple of days, but this comes as a complete surprise. I don't remember reading anything about such a  long period.

 

Another example of how little I know.

 

I can understand your 'in service' comment more easily  they will be kept under compression.

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