To buy or make a coil winder?

[Yorkie]

The original forum thread is here Nick:

http://golbornevintageradio.co.uk/forum/...p?tid=3710&highlight=Coil+Winder

I've attached a few pics and diagrams which might be of interest.

You'll see that I put the feed reel on a shaft supported by arms extended to the rear of the winder so that the  'angle of approach' of the wire from the feed reel to the pulleys which are used to traverse back and forth by hand is less acute. I didn't bother  using ball races on the ends of the driven shafts as it's only for occasional use. Initially I used a 'tally counter' (one of those 'clickers' that coach drivers et al use to make sure they haven't left a passenger stranded) to count the turns, operated by a lever and cam, but then I found an excellent shaft driven turns counter quite cheap so I fitted that.

The wire for my field coil was 0.152mm, (6 thou – approx 38 SWG) solderable enamelled copper wire. Wire of this thickness (or rather ‘thinness’!), is 5,588M in length per kG, and has a resistance of 0.85 Ohms per Metre – 4,750 Ohms per kG.  Thus, for my 2,000 Ohm field coil I needed 2,353 Metres (2.3 km!) so a 500G reel (2,794 Ohms) was sufficient. With such a length of wire and many thousands of turns, a hand-powered winder was out of the question, which is why I set about making a winder powered by a sewing machine motor and a foot-operated speed controller.  I'm not sure how it would cope with the much finer wire used in inter-valve transformers. (I think that Gary also used 38SWG wire, but his coil was much higher resistance (just over 5k Ohms) and hence, took approx. 7.3 kms of wire - almost 38,000 turns!). In part two of Gary's article he covered re-winding an inter-valve transformer - approx. 15,000 turns of 42SWG.

Sewing machine motors and controllers often crop up cheaply on e-bay, and even new motors and controllers can be bought for under £30.00. I turned a large diameter pulley for the coil driven shaft to step down the speed from the motor. For the belt, I used plastic belt that you join by warming the ends and pressing it together.

Hope that's of interest.  

(Given that you're all packed up ready for a move up north, I don't think you'll get permission from the 'head of the household' any time soon to start meddling around with coil winders - don't even think about it!)