|Three Bellows instead of
I made my John Smith Busker Organ as well as I possibly could. To my
frustration I found that, no matter how much I adjusted everything, I could
never get the beautiful sounds that appeared on the video.
It was due to a pulsating air flow from the resevoir. The reasons for
this were no doubt many (bad workmanship?). I decided to tackle one
of the possible reasons, and to my delight struck success.
I changed the two bellows to three. Three bellows of course never have
a momentary "off" position like two do and the result is a much smoother
air flow into (and out of) the reservoir. I then found that the pressure
of the spring which closes the resevoir was much easier to adjust. I
also found that tuning the pipes was easier due to the smoother sound that
was being generated.
Building the bellows with three pumps proved no more difficult than building
two. I just made them narrower (64mm rather than 98mm). The resevoir then
had to be a little bigger to cover the three valves. That I imagine only
helped my cause.
All the best for your building - John Hutchison
(Although smoother, 3 bellows will not provide as much air as 2
bellows in the same space. This is due to the wasted space in between. This
is the reason why most commercial organs only use a single double-acting
bellows to get the maximum amount of air from the minimum space. If space
is not a consideration, then more bellows will indeed provide a smoother
wind supply - MW)