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PIANO WIRE WRESTLING
BY THE BURGLAR......ALIAS TOM SPARKES
I am sure you have all had unfortunate encounters with the dreaded piano
wire,particularly if you are a scratch builder of larger models and have had to
do some fancy bending of this dreaded material. I must admit to a certain
advantage in this area being a retired Musical instrument maker and
musician.
Some of the piano wire in the elcheapo ARF models these days can be very
doubtful in quality. Usually the better quality stuff will be a rather dull grey in
color,as against the very shiny almost plated (sometimes it is !!!) stuff you can
see in some ARFs. Hobby shops usually have the good stuff.
Next thing you need is a propane torch like the plumbers use, that is of
course if you have not got oxy gear or something equivalent. The burner to
get on the end of the torch is called a jewelers burner which will give you a
very controllable flame.
Figure out where your bend has to go and mount it in your vice (a must have
item) and mark where your bend has to be with a permanent marker, with the
mark sticking out from the vice about half an inch. The free end should be
now sticking out from mark and vice.Gently heat the wire right on the
mark,while at the same time grabbing the free end and putting considerable
bending pressure on it in the required direction. You have to be very careful
not to get it too hot,if you go to red heat it is all over rover and you have
destroyed the temper. The heat required is just approaching purple,even a
straw color is too much.You will feel the wire start to give as you keep the
pressure on it ,juggling the heat with the pressure will give you a perfect
bend.Of course a bit of practice goes a long way with all this,try a few
practice bits first.
We have not finished yet of course.Let it cool down, then gently reheat it , not
approaching your original heat by a few degrees, then you can dunk it in oil to
restore the strength and more importantly take some of the strains out of it.
DO NOT DUNK IT IN WATER.The best oil to use is engineers hardening oil,
but I do not think many people will have this in the workshop cupboard.
Ordinary motor oil will work also, just make sure you don’t start a fire and get
offside with the wife as well !!!
Believe it or not, it is quite possible to drill a hole in piano wire,for instance if
you want to retain a wheel with a split pin or want to make a quick connect
attachment in the support cabanes on a biplane.The big secret is a product
called “tap magic” ,which comes in a small can like an oil can. You can get it
from an engineers supply shop like Mitchells Engineers supplies in
Hornsby,which is where I get mine. It is a very thin lubricant and it does work
like magic if you are tapping a thread in any material like aluminium,which
does tend to tear a bit. But it also works a treat if you are trying to drill holes
in difficult material like piano wire. First file a small flat where you want to drill
the hole. Then centre punch it as deep as possible. Use a good quality high
speed steel drill (not an elcheapo carbon one) and flood the drill and punched
hole with the tap magic. Use a drill press if possible and go slowly, backing
out lots as you go. Of course it is even easier with a carbide drill, but they are
very expensive and brittle to boot especially in the smaller sizes.
Thats all for now, good luck with your round one of piano wire wrestling, and
next month I shall delve into the secret and black art of Silver soldering.
THE BURGLAR

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