My second try at building a bellows worked pretty well but there were two problems. First, the way the bellows were designed, the top plate had to travel 4 inches in order for the curtain valve to go from full closed to full open. This meant that the top plate had to move a good bit for each change in wind demand. Add to that that the top plate was fairly heavy and you end up with spikes in pressure whenever the demand changed. This resulted in a bouncy sound to the organ. The second problem was that the bellows had a variation in pressure of 0.1 inches of water depending on the demand. This made it impossible to tune the small pipes as they are very sensitive to pressure. So to solve both of these problems, I decided to remake the bellows. The new design has a valve that fully opens with only 0.75 inches of of top plate travel. Also, the top plate and everything that moves is light and therefore can move quickly to adjust to changes in demand. The end result is a bellows/regulator that keeps the pressure within 0.01 inches of water. There is still a small out of bounce but let's just call that "flexible wind".

Here are the new bellows:

Here's the new valve. The top plate connects to the end of "L" shaped piece:

Rubberized cloth covers the top. The wire in the middle connects the valve to the top plate:

Here's the roll bar that insures parallel travel of the top plate:

The bellows installed:

Inflated:

Final spring design: