Hi Everyone,  First of all I would like to wish you all a happy
and mechanically musical New Year.  Organ blowers are unreasonably
expensive when you consider just what they consist of, particularly
for an amateur builder when a new blower might well cost many times
the cost of building the rest of the organ.

Here in England we have found a good solution in the form of Flymo
impeller blades.  These can be bought new or found used at many
garden center repair shops.   They are designed to run at high speed
and come in number of sizes.  My 98-key dance organ has been using
one for the last four years, it is one of the larger blades bolted
to a normal 2870 or so RPM induction motor of 700 watts.

The casing is just 3/4" particle board with a "snail" made from 1/8"
hardboard which is positioned to vary from about 1/4" gap at one end
to about 1" at the delivery end.  I found that the measurements were
not critical; it is only important to round off the edges at the exit
hole, and perhaps the inlet as well -- failure to do this and you will
have made a siren.

My unit has worked faultlessly often all day and is quiet enough to be
unnoticeable.  The pressure is about 5-1/2" water gage.  In North America
the motor would be faster and would probably give nearer 7" W.G.

For a smaller organ I have recently made a very cheap and simple version
using a smaller blade and a new Chinese bench grinder motor.  A very
good combination as there is no engineering to do: just replace the
grinding wheel with the impeller.  I originally had my doubts about the
motor as it got very hot so I removed the metal outer casing and fitted
it in a shroud so the inlet air passes over it and solves the problem.
This smaller unit gives 3" W.G., in USA nearer 4".

While a blower is a very easy option for feeding an organ, bellows are
much more efficient.  There is probably a 4-to-1 saving in power needed
to produce the required air.  In a small portable organ this could mean
only having to carry a very small generator around.  Remember that
induction motors have enormous start up currents so a motor that will
run on 700 watts needs two or three kilowatts to start it.  My latest
organ, "Topsy", has 64 keys and 79 pipes and yet it will run all day on
a 12-volt 30-ampere-hour battery.

John Smith
Flitwick UK

 [ MMD Articles on organ blowers using the Flymo blade:
 [ http://mmd.foxtail.com/Archives/Digests/200205/2002.05.25.05.html
 [ http://mmd.foxtail.com/Archives/Digests/200301/2003.01.09.12.html
 [ The Flymo hover mower is described at http://www.flymo.com/
 [ -- Robbie