Making Bellows two

The first part of making the bellows is cutting out the wooden ply that will make the top and bottom. The top and the bottom of the bellow needs to match and be square. Other wise the cloth will twist, not fold properly and tear.

Next the valve holes must be made. The valves on the bottom can go anywhere really. But the ones on the top of the bellows must allow for the reservoir to sit on top of them. It is very important that the valves on the top are allowed to act freely with out the reservoir getting in the way.

The shape of the bellows takes in to account where to connection rods go which attach to the crank shaft and make them go. Batons are used to give more space for the fabric of the bellows to stick to, and to make them more durable. I think its important to make every thing as durable as possible because I don't know what sort of effect the strain of the air will have on it.

I learnt allot more from making the bellows than I did from trying to read about them. When I got my first valve to work it was very exciting. It was good to feel that I was doing something right.

The 10 mm holes need to be free from splinters and have a very flat surface for the leather to sit on. You want the leather valve to really get a good seal on the wood and this is impossible if it have any bumps.

The leather flap is screwed into the ply over the valve holes with a restricting strap across it. It is that simple. The tricky bit is making sure that everything is air tight.

The next task was to make the hinge. As you can imagine you can't use normal hinges as air would come through. You must put a strip of blackout cloth on the inside and the outside of the opening/closing side. As the name suggests blackout cloth is used for blocking out light. It is used behind curtains and very commonly in theaters. I STRONGLY recommend masons in Oxfordshire for anything fabric related. Even in London I find it hard to beat them. Now they also have a website:

http://www.masonsneedlecraft.co.uk/default.aspx

These strips of stryne give the bellow room for the bellow leather.

The cloth needs to be cut to size and the card stiffeners need to be glued on. I found that it was very important to mark these out accurately or it wouldn't fit and fold correctly. If this is wrong the bellows would puff out not keep pressure. I decided that using styrene would be better to use as it is just as thin as card but stronger. The leather used for the bellows needs to be top quality as it all needs to be completely air tight. The leather I had was half length so I simply glued two pieces together with fabric glue.

I was originally going to use PVA as recommended by John Smith the organ builder. But I was recommended to use contact adhesive by a colleague. This made much more sense as it is more flexible and strong. It will do a much better job attaching fabric to wood. The bellows needed to be put in a vice and very carefully the fabric needs to be put in the right place. I found it wise to do some tests with out glue first.