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Author Topic: Bellows fold sizes  (Read 5911 times)

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911377brian

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Bellows fold sizes
« on: June 03, 2017, 12:28:13 PM »

I've got a couple of the Child Prodigy type kids melodeons that have been Hohnerised by Mike Rowbotham and they play remarkably well. The bellows are always the weak link though and I've been in touch with Igor to see how practical it would be to have new bellows made. The smallest depth of bellows fold Igor can do is 25mm, the depth of fold on the Child Prodigy 16mm. Can anyone tell me if the difference in fold depth will have a detrimental effect? I've got round the problem of air loss up to now by glueing two sets of bellows together, however, Lester has recently retuned one for me from C to b flat with the original reeds and that plays OK with single bellows...
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Steve_freereeder

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Re: Bellows fold sizes
« Reply #1 on: June 03, 2017, 02:49:12 PM »

... The smallest depth of bellows fold Igor can do is 25mm, the depth of fold on the Child Prodigy 16mm. Can anyone tell me if the difference in fold depth will have a detrimental effect? ...

You would need to check that the deeper bellows folds do not contact or otherwise impact on the reed blocks. So long as there is (I'm guessing) about a centimetre minimum clearance between the interior of the bellows folds and the reed blocks you should be OK. If the bellows folds are too close to the reed blocks there is the risk of the reed tongues and/or valves contacting the folds during playing and also could have an impact on the tuning (it would flatten the pitch a bit).

Before you order new bellows it might be worth making up a 25 mm folded thin card mock-up of a section of bellows and looking to see if it would contact the reed blocks when held in place.
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911377brian

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Re: Bellows fold sizes
« Reply #2 on: June 03, 2017, 03:12:38 PM »

That is an excellent observation Steve and the possibility of the folds engaging the reeds hadn't occurred to me. Thanks
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malcolmbebb

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Re: Bellows fold sizes
« Reply #3 on: June 03, 2017, 03:14:15 PM »

The quick answer is no.

You have less than 10mm clearance top and bottom on the bass block, which extends (albeit not far) into the bellows space, and next to nothing at the sides.

On the treble end you have less than 10mm on the sides, nearer 5mm, and 10mm or less on top which includes room for reed and valve travel.

Malcolm
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malcolmbebb

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Re: Bellows fold sizes
« Reply #4 on: June 03, 2017, 03:21:50 PM »

Actually the basic cardboard of the bellows is not bad. The real bugbear is the white cloth stuff (NCB knows what it's called) that they used for gussets and for the corners, which makes the average colander or sieve appear airtight by comparison.
Unfortunately (on a sample of one) the glue used to fix this stuff is probably the strongest and most durable part of the entire box and I couldn't figure out how to shift it without wrecking the cardboard. But by the time that's a problem it's all getting a bit major anyway.
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911377brian

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Re: Bellows fold sizes
« Reply #5 on: June 03, 2017, 03:31:38 PM »

You just beat me to the draw Malcolm. Having pulled one of them apart it's very clear that there is no room for bigger folds. Silly thing is I hadn't given that aspect any thought.
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malcolmbebb

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Re: Bellows fold sizes
« Reply #6 on: June 03, 2017, 03:37:18 PM »

Well, while I had the box apart, there was a reed that hadn't been working for ages (as I couldn't be bothered to open it just for that). Quick ping and it's happy again.
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Dino BPII.
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911377brian

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Re: Bellows fold sizes
« Reply #7 on: June 03, 2017, 03:40:40 PM »

Just a thought, anyone know of another bellows maker who might do smaller folds....(better to die an optimist)
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Steve_freereeder

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Re: Bellows fold sizes
« Reply #8 on: June 03, 2017, 06:17:51 PM »

Actually the basic cardboard of the bellows is not bad. The real bugbear is the white cloth stuff (NCB knows what it's called) that they used for gussets and for the corners, which makes the average colander or sieve appear airtight by comparison.
Unfortunately (on a sample of one) the glue used to fix this stuff is probably the strongest and most durable part of the entire box and I couldn't figure out how to shift it without wrecking the cardboard. But by the time that's a problem it's all getting a bit major anyway.
Yes - the white cloth stuff is awful. I fixed one of these boxes for a friend a couple of years ago. The gussets were split and leaking badly so I patched them with some skived thin leather patches which I cut from thin leather supplied by Mark Adey for mending concertina bellows. It bulked up the bellows a bit, but it stopped the leaks and was quite flexible.
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Psuggmog Volbenz

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Re: Bellows fold sizes
« Reply #9 on: June 03, 2017, 08:52:05 PM »

It isn't any harder to make bellows with shallow folds, just different layout of the folds. I have also made replacement bellows for view cameras. Even  tapered shapes are possible. While the camera bellows don't have to be airtight, they must be light tight. They also have no gussets.
« Last Edit: March 30, 2018, 03:56:22 AM by Psuggmog Volbenz »
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911377brian

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Re: Bellows fold sizes
« Reply #10 on: June 03, 2017, 09:28:21 PM »

Igor doesn't have folded card smaller than 25mm, PV, that's the problem, and having read plenty of posts on the subject here on Melnet the thought of attempting to make a set of bellows fills me with dismay, not to say terror :-\
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Nick Collis Bird

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Re: Bellows fold sizes
« Reply #11 on: June 07, 2017, 03:09:49 PM »

Actually the basic cardboard of the bellows is not bad. The real bugbear is the white cloth stuff (NCB knows what it's called)


Jaconette !
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911377brian

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Re: Bellows fold sizes
« Reply #12 on: June 07, 2017, 04:03:46 PM »

Hi Nick! I just managed to avoid reactivating the old 'Chanson' thread with this post...I'm going to try and fit leather gussets from the inside of the bellows, leaving the jaconette in place and glueing the leather to it. Think it will work? (You can probably tell that  I'm bored witless at the moment)
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malcolmbebb

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Re: Bellows fold sizes
« Reply #13 on: June 07, 2017, 04:44:31 PM »

There is a material called "Goldbeaters' Skin", or something like that. Charlie used to sell it as Zephyr IIRC (may still do) which is astonishingly thin and strong.
Just a thought, it might do what you need without too much bulk.

If you decide to go with leather, Concertina Spares used to sell some very thin leather for repairs. Rather easier to handle.
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Dino BPII.
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911377brian

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Re: Bellows fold sizes
« Reply #14 on: June 07, 2017, 05:17:47 PM »

Thanks Malcolm..I'll chase that up..
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Nick Collis Bird

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Re: Bellows fold sizes
« Reply #15 on: June 08, 2017, 09:19:12 AM »

Hi Brian,
I don't understand when you say leave the jaconette in place and fit the leather gussets from the inside. Surely the leather should be on the outside. :o.
  Don't be bored: there's plenty on here to amuse and educate.
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malcolmbebb

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Re: Bellows fold sizes
« Reply #16 on: June 08, 2017, 09:46:46 AM »

Getting the jaconette off is a full bellows rebuild.
Putting the leather on the inside will work just just as well, but won't notice if you make a rough job of it.
Either way it will bulk up the bellows a bit.

Don't ask me how I know.
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Dino BPII.
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Nick Collis Bird

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Re: Bellows fold sizes
« Reply #17 on: June 08, 2017, 10:37:34 AM »

Don't you end up with jaconette on the pretty side then?
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911377brian

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Re: Bellows fold sizes
« Reply #18 on: June 08, 2017, 11:19:46 AM »

I've just won a kiddie box on eBay for a fiver, perfect test bed. PVA good as an adhesive Malcolm? Can't face leathering the outside Nick what with repapering the folds etc. I remember your problems with making bellows Nick, even with your bookbinding skills and machinery at your disposal. I think it shortened your life a bit... ;)
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Nick Collis Bird

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Re: Bellows fold sizes
« Reply #19 on: June 08, 2017, 11:39:17 AM »

Too true Brian! PVA is good but make sure it's not woodworking stuff. It's very brittle.
Paste is ideal, but you need patience. Quite a long drying time but you get to able to move it about for sometime if needs be.
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