I have dismantled a number of Bontempi chord organs.  The cheaper
organs have a tiny blower, formed into the moulded plastic case, and
plastic reeds as well.  The more expensive wooden cased models have a
better motor, but none of them in my experience have a blower capable
of developing anywhere near the 6 - 7 inches water-gauge needed for the
John Smith Universal organ pipes.  In each case the Bontempi motor was
a shaded-pole type with very limited power.

Some years ago I built a blower using a 15-inch diameter turbine
impeller from a junked Flymo lawnmower.  I made a box of 3/4-inch
chipboard, 18 inches square, 3 inches deep, with large inlet holes in
the centre of each.  The internal "snail" was made by bending a strip
of thin MDF, attached to wooden blocks.  The blower was driven by a
2-pole 1/4 hp induction motor at 2850 rpm and it delivered 6 inches of
wind quietly and in great quantities.

This could be a low-cost solution to the problem, but it is essential
to use a high speed motor.  A normal four-pole induction motor, with
its speed of 1425 rpm will give barely 2 inches of wind.  Another
requirement for steady wind is a reservoir bellows with suitable
springs and a spill valve set to the required wind pressure.

I later acquired a professional blower for my organ.  I gave the Flymo
blower to John Smith, who still uses it in his MIDI fair organ to this
day.  Several other amateur organ builders have since copied this idea.
Its cheap and it works!

Bob Essex.  With best regards from snowy Warwickshire
in the heart of England.