Raphi Giangiulio's Homemade Pipe Organ

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Bellows
(first try)

I'm not sure if this is really a bellows. Maybe I should called it a Schwimmer. In any case, it will regulate the pressure. I got the basic design from the following website. The bellows is divided into two sections. The input section which will have a pressure equal to the output of the blower, about 3 inches of water. The output section will be regulated to about 2 inches of water and will feed air through conveyances tubes to the windchests. The top plate of the bellows will float on a piece of loosely attached leather. The force on the top plate is held almost constant through the use of two pantagraphs. The total force on the top plate needs to be 8.82 lbs so each pantagraph is designed to have 4.41 lbs of output force. As the bellows inflates, the top plate will rise and gradually pull a valve closed. The valve is mounted to a balancing bellows so that the valve is not affected by the pressure. When the organ needs air, the top plate will lower just enough to allow air to fill the demand of the pipes being played. Of course if you play every pipe at once, the valve will open all the way but the blower won't be able to maintain 2 inches of pressure. Hopefully the blower has a large enough capacity to adequately supply my organ with air for most playing conditions. My bellows aren't large enough to act like a reservoir, just a regulator.

Here are some photos of the balancing bellows. The fixture on the right will hold the two rings in place while the leather is applied.

Here's the balancing bellows mounted to the fixture and ready for leather:

This is just after the leather has been glued in place using hot hide glue.

This photo shows the leather trimmed up, the felt and leather piece glued to the top side and some stitching I added to the seam of the leather.

This photo shows the bottom of the bellows. The rod that will connect the valve to the top plate passes through a hole in the bottom that will guide the valve and keep it centered. There is another guide hole above the top plate that we will see later. The large hole to the right of the rod is to allow air to freely enter and leave the balancing bellows as the valve moves up and down. The six screws attached the balancing bellows to the bottom of the bellows.

The following photos show the valve and balancing bellows assembly mounted in the input side of the bellows. The hole is 4 inches in diameter.

This is what the regulated side will see when the valve is closed.

Here are some assembly photos: This shows the separation of the two parts of the bellows. The blower input is the hole on the right side and thus the bottom section is the high pressure part of the bellows. The top part and left side will be the regulated part of the bellows. The large bosses are for the top plate to rest on when the valve is completely open. The four holes on the left are for the conveyances tubes that will go to the windchests. I think I'll only need three but I put four in case I need an extra.

Here the leather is installed. It is held in place with a piece of wood screwed down over the perimeter.

This is the top plate that will float up and down as the demand for air changes.

Here is the complete bellows:

Here's a photo of the pantagraph. The spring is permanently fixed at one end and the other end hooks on a threaded eye hook. The nut on the back of the eye hook will adjust the tension in the spring and thus the pressure of the regulator.

There is a roll bar that will prevent the top plate from tilting side to side. It looks and works just like an anti-roll bar in a car. It forces each end of the plate to travel together. The first photo shows the roll bar across the front of the bellows.

This photo shows the linkage between the roll bar and the top plate.

This photo shows the piece that will guide the top part of the connecting rod.

Here's the bellows fully assembled and mounted to the frame and blower case:

Click here for a video of the bellows inflating.

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