Bellows The Hard Way

[Dana Johnson]

Many years ago I visited Steve Dickenson's shop. While I have used the core or tube type bellows forms for odd sized or non hexagonal bellows, I much prefer these molds which are a close approximation of what he used from the old Wheatstone factory. They are not difficult to make out of wood, though I impregnated my one wooden version with wax to keep glue from sticking. They are meant to be used with the bellows frames mounted and an integral part of the bellows making process. The aluminum versions are great if you are making a lot of bellows. Steve's aluminum versions were cast metal, I just milled mine from bar stock 6063 aluminum, and precipitation hardened them in my baking oven. The bars swing to the empty center and are pulled out the ends when finished. I recently split them and added inserts to do 5, 6, 7 or 8 fold bellows. Steve's had small central wooden cores that had a channel down the center of each side that a bar on the mold sides fit into. I just put a short section of core on the end plates to keep everything alligned. The clamps for the finished bellows are two parts, one interior set (not visible) to compress the inner folds (Chris Ghent mentions this). And the end pieces to compress the peaks.

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Dana

Edited April 22, 2017 by Dana Johnson

[Jake Middleton-Metcalfe]

Great looking moulds. Why is this the hard way though? I always thought this was the best way

[Dana Johnson]

Only hard because you have to make the molds, which are a bit of work compared to the hex or octagon cores or easier yet a piece of pvc pipe. Having done it both ways, the extra support the molds give to the folds when gluing the gussets or butterfly's/papers depending on style, is nice. The down side is the fixed angle at the ridges, which only means you want to allow for the top runs to stretch sideways ( not lengthwise ) so the bellows can close. On a core mold, you can pinch the peaks closed when you glue on the top run which means it is glued in the closed position. I get around the stretch by beveling my card at 45 degrees on both the peaks and valleys so the leather bends around a point rather than a square or v shaped ridge. I leave 2mm of space at the bottom when I glue on the inner hinge so the thickness of the covering leather has someplace to fit when folded closed. Steve Dickerson had a jig to lay out the cards with 2mm spacers between them, but I just use a long piece of angle iron with a couple wood strips glued on the side to support the long beveled card strips when I glue on the leather valley hinge. The side support strips are just low enough so the card doesn't get to the peak of the angle iron ( ^ orientation) which leaves just the right gap after gluing, both edges are beveled with the mat cutter / / so when you put the cards together, the outside peak and the inside peak look the same ( you swap ends ever other piece ). /\/\.

[alex_holden]

Wow, excellent work!

 

Here are my much cruder wooden ones:

[Dana Johnson]

Wow, excellent work! :)Here are my much cruder wooden ones:bellowsmoulds.jpg

I wouldn't call them crude at all. Especially since you spent more time doing as nice a job on your stand. I love the octagonal dowel bit on the ends to keep things where you want them.

[alex_holden]

I wouldn't call them crude at all. Especially since you spent more time doing as nice a job on your stand. I love the octagonal dowel bit on the ends to keep things where you want them.

Thanks!

[Jake Middleton-Metcalfe]

Only hard because you have to make the molds, which are a bit of work compared to the hex or octagon cores or easier yet a piece of pvc pipe. Having done it both ways, the extra support the molds give to the folds when gluing the gussets or butterfly's/papers depending on style, is nice. The down side is the fixed angle at the ridges, which only means you want to allow for the top runs to stretch sideways ( not lengthwise ) so the bellows can close. On a core mold, you can pinch the peaks closed when you glue on the top run which means it is glued in the closed position. I get around the stretch by beveling my card at 45 degrees on both the peaks and valleys so the leather bends around a point rather than a square or v shaped ridge. I leave 2mm of space at the bottom when I glue on the inner hinge so the thickness of the covering leather has someplace to fit when folded closed. Steve Dickerson had a jig to lay out the cards with 2mm spacers between them, but I just use a long piece of angle iron with a couple wood strips glued on the side to support the long beveled card strips when I glue on the leather valley hinge. The side support strips are just low enough so the card doesn't get to the peak of the angle iron ( ^ orientation) which leaves just the right gap after gluing, both edges are beveled with the mat cutter / / so when you put the cards together, the outside peak and the inside peak look the same ( you swap ends ever other piece ). /\/\.

 

I see, yeah milling aluminium can be a laborious process, looks well worth it though for a very good mould.

[Dana Johnson]

Milling not too much problem. I cut off most of the excess on my band saw.

[Jake Middleton-Metcalfe]

tell you what this post has got me thinking, thank you for sharing your ideas dana.

 

I am quite intrigued by the technique of bevelling the cards at the top and the bottom to get around the fact the bellows have to stretch to the closed position (given that they were made in the open position)

 

The way I got around this problem was:

 

1: put my runs of cards on the mould (individual cards were joined up off the mould ( mould similar to yours but wooden) and join them all up with a strip of cloth glued allong on the top runs

2: let glue dry for 30-45 mins then take the bellows off the mould and clamp overnight

3:put the bellows back on the mould and glue the gussets and top runs of leather and again wait for 30-45 mins before removing and clamping the bellows overnight

 

this process gave me a bellows that was not acting like a spring always wanting to open.

 

My question is: does bevelling the cards allow you to skip step 2 on my list above?

Edited April 25, 2017 by Jake of Hertford

[Dana Johnson]

Beveling the cards simply makes it so the leather doesn't have to stretch as much. Leaving a little gap at the top hinge point helps too, but I do that only at the bottom. I find that leaving the finished bellows off the mold overnight and then putting it in clamps works well enough. They do want to open a little for a while, but if they are closed in the case, they tend to stay closed fairly quickly. Leather seems to like to take a set in whatever position they are left in. After playing for a while, it loosens up and ceases to resist in either direction. I have a silly machine that opens and closes the bellows 30 times a minute. I leave the bellows on it for a few hours and it is pretty good to go afterward.

I use vegetable tanned goat leather for it's toughness , but it needs more breaking in than most chrome tanned leather, some of which is very soft. If you use that stuff, you can have a very limber bellows, but I don't personally trust it or like it's working properties.

I don't bother taking the bellows off the mold after the cloth strip stage, with the bevel, the cloth is so thin, that there is no appreciable stretch since the cloth lies at the center of bending. Thicker leather has to stretch because the outer part of the curve covers more distance than the glued surface does. Thin leather top runs help, but too thin and it substantially weakens the leather.

If you don't bevel, the cloth needs to be pressed into the bottom if the shallow v the cards make at the peaks. If you just stretch it over the top when you glue, it acts like a bow string and you'd need to clamp because the double card thickness is longer than the hypotenuse of that v. If you bevel, that distance is zero. Since it is really easy to bevel the card with a mat cutter when you are cutting the sheets into long strips, I don't see a reason not to.

Dana

[Jake Middleton-Metcalfe]

very clever and simple, Love it. I will have to try that at some stage, cheers mate.