| Some time ago I read an article in the "Model Engineer "magazine
about constructing a Busker organ using plans by John Smith. I spent most
of my working life in engineering and in my spare time have made various
clocks and a working scale Steam Traction Engine. I am now retired
but an active member of the Wirral Model Engineering Society and have helped
with the construction of 5" raised and 71/4" ground level tracks in a local
park where the club members run their locos and offer rides to the public.
I have always been interested in Fairground type organs I and thought one
would be useful, amongst other things, to entertain the queue waiting for
rides. Working at 8 W.G. it would not pose the safety issues of high pressure
boilers and the only public liability would be the effect on the ears which
I have not found a problem, "What's that you say"?
I consider myself a man of many parts, some of which are still in working
order but have never contemplated making an organ until I read the aforementioned
article, so I purchased a copy of John Smiths plans for the 26-Note Universal
Organ. When I started in engineering I used to be asked to make things from
sketches on 'Woodbine' packets so I considered following John's plans a
possibility.
Taking the dog down to the beach for a walk one day I had the good fortune
to park the car by a residential home which had a skip outside. As the dog
and I got out of the car a builder emerged from the home with some large
planks of seasoned pine which he dumped in the skip. He said that I could
have what I wanted so the planks were transferred to my car and the decision
was made to start on the Organ.
I next ordered a tuning meter, 26-note test roll, 6'x4' sheet of 1/4" birch
ply, 6'x4' sheet of tempered hardboard, large bottle of PVA glue, leather
for the bellows, valves and puffs, boxes of twin threaded woodscrews, 1.0
mm and 0.5 mm sheets of cardboard, and acquired some chunks of mahogany type
wood from various friends. As you will be familiar, or can become familiar,
with John's plans I will mainly describe the changes I have made in my version
of the construction which I have personalised as "Tonyphonic".
I constructed most of the organ using a circular saw bench, a planer/thicknesser,
bench drilling machine and rotary sander, but had to use the lathe, flypress,
milling machine and dividing head for some of the changed items. I
had to carefully plan the cutting of the birch ply as the whole sheet was
required in the construction of the case, bellows/reservoir, pressure box
etc. there being only a few scraps left over. The edging and base was made
of pine. I made a special 1/2" fly cutter for the bellows/reservoir assembly
so that I could obtain a nice sharp edge on the holes to give a good seal
with the leather valves. All the wood was treated with 'sanding sealer' which
brought up the grain and when re-sanded produced a nice smooth finish. The
wind chests have a number of holes that need good edges for sealing the valves
and these are in tempered hardboard which tends to throw up a burr if drilled.
I found that punching these holes on the flypress gave a nice square edge
so all holes in tempered hardboard were produced in this way. The sliders
are made of plastic ABS sheet with the holes punched in the same way and
the cover strips are made up of two pieces of tempered hardboard glued back
to back so that there is a smooth surface on both sides. The holes in these
were also punched. I have not used any M.D.F. The two reservoir springs were
produced on a home made bending jig from 1/8"piano wire and give exactly
8 W.G.
The seven bearing crankshaft is fabricated in mild steel with aluminium housings
for the ball races, aluminium connecting rods with threaded length adjusters
and self aligning rod end bearings at the little end. All shafts in
the pressure box run on ball races, the take up spool being made of black
plastic drainpipe, the flanges of which are cut out of black Bakelite sheet
as is the music roll holder. The tracker bar is constructed from 1.5"diameter
black anodised aluminium rod which was originally the platen taken from an
old printer as were the 1/4"diameter pressure rods either side of the Perspex
window. The pressure rods are mounted on ball races but there is not enough
friction with the roll to rotate them. The anodising produces a clean smooth
surface for the roll to run on. For indexing the tracker bar had to be drilled
while mounted in the dividing head on the milling machine table. The holes
were drilled from the top down to the centre of the bar then it was rotated
by 120 degrees and another hole drilled to meet the first. The next
tracker hole was drilled in line with the first except this time the bar
was rotated 120 degrees in the opposite direction bringing the hole out on
the other side. Bringing the holes out on alternate sides allowed enough
space to accommodate the aluminium nipples which connect the plastic pipes
going to the bleed bar.
I decided against friction devices and belts for connecting the drive from
the crankshaft to the take up spool and plumped for a gear drive instead.
I made the gears from 'Delrin' because it is self lubricating, quiet and
I had a bar of it in stock. I made them 16 DP because I had the cutters and
all the gears run in their own ball races. This makes the whole assembly
maintenance free which is a good job as I glued up the case in this area
to avoid showing screw heads and now cannot get at it. The clutch that
disconnects the drive during rewind is made from two Meccano contrate wheels
which lock into each other like a multi tooth dog clutch. This is operated
from the back of the organ by a square push rod with limit holes that locate
with a ball and spring.
The bass pipes and bass helpers were made from pine, a quantity of which
had been cut and planed into 1/8"and 3/16"sheets; the rest of the pipes were
made from mahogany which had been prepared in the same way. Three of the
bass pipes had to be mitred to get them into the base but by increasing the
case height slightly I avoided having to mitre any of the accompaniment or
melody pipes. I did not encounter any difficulty in tuning the pipes
with the tuning meter or setting the bleeds with the test roll.
I used 1/8" x 1 1/4" bright mild steel bar for the Glockenspiel, cutting
each bar a little longer than John's dimension and grinding the ends until
it was in tune with the meter. It makes a difference where the fixing holes
are drilled in the bars. They should be drilled at the nodes these being
0.224L" in from the end of the bar (where L is the length of the bar in inches)
thus allowing free resonance of the bar. The bars sit on felt discs and there
is a piece of silicone rubber tube between the pin and bar hole as in John's
organ. The hammer shafts were made from 3/32"bronze brazing rod with hardwood
hammers at the ends. I had some 24swg piano wire that I used for the return
springs and this works a treat. The bars were treated with a commercial
blackening solution which gives them a uniform colour and should deter rusting.
To bring the organ up to cranking height and transport it I have made a wheel
barrow-like trolley similar to that made by John Pettifer. This is a GT version
with alloy wheels and removable handles. It has four tapered spikes on the
top which locate with mating holes in the base of the organ and prevent it
parting company during transport.
I know that I am getting old but having completed the organ I found that
I could not pick it up to load it into the car. It only weighs 82lbs (37Kg
for metric people) but is an awkward shape (being about 25"square x 37"high).
Only having handles at the side means increased leverage with arms
outstretched. Also having no bottom to the case one has to be careful not
to damage the bass pipes. I got over this by constructing a trestle the height
of the car cargo area, lifting the organ on to this using a home made electric
hoist and sliding it into the back of the car. It is easy to pick up if there
are two people so getting it off the other end is no problem.
The whole job took nine months and after obtaining some rolls of Melvyn's
excellent music I took it to the park and played it to the enjoyment of all
but the stone deaf. Despite much searching I have been unable to find
a monkey who is prepared to turn out and collect money, so rather than get
into cloning or genetic manipulation perhaps my next job should be to produce
a mechanical one.
See Mechanical Monkey |