I'm building myown galvo motors and for that I need some coils that I'll have to build myself to fit into the dimensions I need. Is there any technique for winding the wire or is it just straight forward hand winding? Any trick or detail that you could share would be very useful as well.
The coil winding methods described in
Using miniature sensor coils for simultaneous measurement of orientation and position of small, fast-moving animals C. Schilstra, J.H. van Hateren *
Department of Neurobiophysics, Uni6ersity of Groningen, Nijenborgh 4, Groningen, NL-9747 AG, The Netherlands 1998
may be of substantial value.
They produced 3 orthogonally mounted coils, each of 2mm diameter and 40 to 80 turns & weighing 0.5 to 1.6 grams/coil. These were mounted on a blowfly to allow real time monitoring of its position and velocity when in flight. A later paper resports the mounting of a second coil set on a fly's head so that head movements relative to the fly's body can be measured while in flight.
The main equipment - sometimes the darkest of the arcane arts appears deceptively simple :-):
Amongst other details they say:
... we use thin wire of 12-um (micro-metre) diameter (with
two layers of insulation, 1 mm polyurethane and 1 um
polyvinylbutyral; Lotan-Fix, Huber and Suhner,
Switzerland).
The coils are produced by winding the
wire around a hollow axis of flexible material (Teflon;
see Fig. 3 for the device used for winding coils). Before
winding, a thin metal expansion rod is inserted into the
hollow axis; the fit is such that this slightly increases the
diameter of the axis.
Approximately 1 m of wire, later
used for connecting the coil, is first wound on a storage
reel. Subsequently, the coil is wound, and glued
together by slightly heating the outer layer of the wire
insulation. Removal of the metal rod loosens the coil
from the axis, after which it can be shifted from the axis
with the help of a tightly fitting glider (Fig. 3).
To
prevent breaking of the wire, a tension loosener loosens
the wire before the coil is shifted from the axis. Finally,
the wire is unwound from the storage reel, and twisted,
by means of a motor, with the other wire originating
from the coil. The tension during the twisting is
controlled by hanging small weights at the end of each
wire (Koch, 1980). Careful twisting is essential to
prevent induction of voltage in the resulting leads.
and
With the technique described above, we are able to
make coils as small as 0.8 mm in diameter, but for most
experiments we used coils of 2-mm diameter, with 40 or
80 windings. This gives a good compromise between
weight (0.8–1.6 mg for the three coils) and signal-to noise ratio:
Fig. 3 (inset)
shows the resulting system of three coils. These were
made with slightly different diameters (2.0, 2.1, and 2.2
mm) such that they fit within each other. The coils are
fitted together as orthogonally as possible using a template with orthogonal grooves.
The ability to use 12 um dia wire (0.012 mm), to produce coils down to 0.8mm in diameter and to make coils with diameter tolerances of 0.1 mm (2.0, 2.1, 2.2 mm) demonstrate a degree of mastery of the methods involved which should be far more than what is required for galvanometer winding. One would hope :-).
Supporting material but of far less detail is found in a follow on paper BLOWFLY FLIGHT AND OPTIC FLOW
I. THORAX KINEMATICS AND FLIGHT DYNAMICS - 1999
Potentially useful information relating to use of coils is found in Induction coil sensors—a review - 2007.
This is more about applications and electrical design but will be at leasts of injterest and the 95 refernces will provide some extra material.
