Hand Coil Wave-Winder

[Yorkie]

One thing I have read somewhere is that it is beneficial to sparingly apply shellac varnish as the coil build up, to prevent the turns slipping off, and then apply a layer after the coil is finished. Have you tried this idea, or do you have any thoughts on it?

Andy

A good idea Andy.

Cellulose sanding sealer (rather than shellac sanding sealer) dries very quickly - in seconds rather than minutes, and likewise would clear dope as used for aero-modelling tissue, so could be applied say every 50 turns, but I purposely didn't try applying anything during winding as they didn't in the film and I wanted to see if the turns would stay on. If you look at the film, you'll see that the turns are widely spaced - not close together and that's what happens when the rubber drive disc is closer to the centre. That has the effect of lowering the inductance, just as it would on a conventionally wound coil with spacing between the turns. If the turns are wound closer together the angle is less acute, and that's when there's a risk of them falling off the edges, so applying a fixative every few turns would I'm sure help.

I did dip the finished coils in hot beeswax and left it in for a little while to heat the coil up so that as much of the wax would drip off the coil rather than solidify in a thick coating.

I think it would take quite a lot of experimentation to get the inductance of the coil just right. I suppose the best way would be to wind a coil with say 200 turns, check the inductance and if too high, take a few turns off at a time till the inductance is what is desired. However, once that experimentation was done, I think consistent repeatability would be possible if the turns and settings of the discs are noted. Of course, if a coil has a slug rather than air cored, it leaves some scope for adjustment.

I've do idea what gauges of wire was originally used by the likes of Denco, REP, Osmor etc, or whether it was Litz or cotton covered. All a bit of a leap in the dark really.

I still don't quite understand how the original Morris winder managed to lay down the waves when the ratio of the bevel gears seems to be 1:1 with no scope for adjustment, risking the turns falling on top of one another rather than side by side, but I may be wrong on that ratio. It must have worked because they did sell lots of them back in the 1930s! I've no intention of going into business winding coils and ought to get out more but it was a rainy day when I had as furtle around with the winder in the week.