last changed 22/09/06
Making Miniature Steering
Steering wheels in the 1/200 or
so scale are really delicate items with an outside diameter of
somewhere between 5 and 10 mm depending on the size of the ship. Here
is a possible method for fabricating them.
Take a piece of dowel of a diameter equivalent to the inside
diameter of the wheel rim. Wind soft copper wire of diameter of about
three-eights of the thickness of the wheel rim round this dowel; two
turns per wheel to be fabricated. Cut off ring from this spiral, making
an oblique cut. Take off the rings without distorting them and solder
them closed with as little solder as possible. Next, chuck these rings
into a wheel chuck (in the absence of such, you can lacquer them onto a
wax chuck or onto a round piece of aluminium into which an appropriate
recess has been turned) which is held in a dividing head. Using a very
sharp flycutter or a small circular saw, shallow notches are cut into
each half of the future wheel rim, the number of which correspond to
the number of spokes in the wheel. Alternatively and if you lathe
headstock has a suitable dividing ring, you can hold the rings in the
headstock and cut the notches with a very sharp lathe tool turned on
its side and centered.
One of the rings is now laid out on a soldering pad and
short lengths of thin copper wire laid cross-wise into the shallow
grooves produced earlier. The diameter of the wire should be equivalent
to the smallest diameter on the spokes and the wire should be carefully
tinned beforehand. The wires need to be fixed to the soldering pad with
tape. A second ring is put on top of the assemblage with some flux
applied. The whole thing is now soldered together. A small blob of
solder fixes the crossing point of the wires. The best thing to use is
a flame or hot air soft soldering gun, not requiring to touch the
delicate arrangement. Also use electronic solder and flux that do not
require washing afterwards.
For the next step a small jig needs to be made, consisting
of two small pieces of flat steel guided by two pins to move parallel
to each other. The surface of the steel pieces should be very smooth so
as not leave any marks during the procedure to follow. The
soldered-together wheel assemblages are now placed between the two
steel plates and judiciously squeezed flat. After the procedure, the
wheel rim should have the scaled-down dimensions of the prototype.
The wheel is now returned to the lathe and mad run true with
respect to the circumference of the rim. A small hole is drilled
through the center to accommodate the axle. The actual wheel hub
consist of two halves turned from brass and drilled. These may be glued
on or soldered with a solder of a lower melting point, so as not to
disturb the remainder of the wheel.
The spokes on the raw wheel are now trimmed all to the
same length. The turned profile of the spokes is imitated by applying
small blobs of white glue or acrylic gel medium. The procedure may need
to be repeated several times in order to build up the right profile.
The wheel is now ready for (spray) painting. Brass trimmings
can be imitated by picking out the respective parts in metallic paint.
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