Douglas No6 Coil Winder

I had a bit of luck on ebay today! I bought a lot consisting of a Douglas layshaft and a part of a wire tensioner for a maiden bid of £13.50 including postage. The layshaft is complete and the tensioner lacks the base, a small pulley and a column which are the easiest parts to make. A dealer selling second-hand tensioners was asking over £100 for a really tatty one so I am very pleased!

Lucky you Brian, I can see it all coming together.
Rob.

An update on my coil winder: I have made a tailstock out of alloy - I had a big lump of the stuff so I decided to make a lot of swarf. The original is lever operated but as I won't be doing any production work, I decided the that was going too far. I could add the lever later! I have also started work on the reel carrier. I've bought a couple of ball races for the reel shaft and so far have the auto friction device working. There was only one Bakelite pulley and that was broken so I have made a couple of new ones from Delrin plastic. It really is fantastic stuff to machine.

Hi Brian

Will it do the GEC coils ?

Ian

(Probably stupid question as I guess that's why you wanted one!)

That's the basic idea, Ian. But first, I have to "design" them for which I have built the replica vision receiver. At the moment, I have the ongoing scan transformer problems which, hopefully, will be sorted soon.

Just a thought, Brian; if you're going to use this for the GEC's IF coils, won't they need to be wave-wound to keep their self-capacity down?

I don't think that there will be enough inductance required for that, Cathy 😉 - it is, after all, only 4MHz - I will be doing some experiments later.

4MHz can be wound by hand

Yeah - but it's much more fun spending a lot longer to restore and then use, a coil winder.

Absolutely, I agree.

I want to re-wind some vintage 1920s transformers (I have three duff ones). These come to bits easily.

I want to make some mains and audio transformers using Bobbins and E I from "dead" modern ones.

I want to wind IF, MW & LW LO and RF coils. All that needs a winder.

But usually at the simpler end of construction a different mechanism for mains/audio vs RF/IF coils is needed. I have collected a load of Douglas/AVO manuals, a Stevens Manual and Gingery's simple RF coil winder design.

I might make some Proof of Concept ideas out of Lego Technic before messing with metal, wood and plastic parts.

I had to buy a copy of a Douglas No.6 manual for £45 and when I got it, I found that there were 6 pages missing. The guy was "good" enough to give me a 50% refund. Michael, in your collection of Douglas manuals do you have a No.6 or a General Purpose Reel Carrier? If so, I would like the last 4 plates from the coil winder manual and the complete GP Reel Carrier.

I have an 8 page No.6 leaflet pdf

I think probably the same as avovcoilc.pdf here:

http://www.kevinchant.com/avo.html

You probably want
avo_reel_carriers_manual.pdf

Thanks Michael. That is the reel carrier info I need. Great!

I spent this evening making a drive cone for the coil winder. The fun in producing this part was the machine setup. I turned a basic cone with a reamed hole to suit the arbor on the winder and then mounted it in a chuck on a dividing head and set it to present the cone at the correct angle to give a 4mm depth at the base of the cone and .1mm at the apex. 16 off 90 degree groves were then machined at 22.5 degree intervals around the cone to give the driving teeth. The pictures show the result - a bit different to the original in the pictures but the teeth are sharp so it should work.

The flattening of the ends of the teeth were an afterthought because without it, the cone was positively dangerous.

The coil winder is now pretty well finished now except for the drive motor which I have been promised next week! Meanwhile I have bought a number of Delrin change gears and machined them to fit the winder. The picture shows it in action together with the reel carrier.

I've got the motor but I must admit, I don't want or need the speed so I decided to add a winding handle. There is a very thick flat area on the casting at the RHS of the machine into which I can bore a hole for a 12mm stud.

The idea is that I use a spare change wheel to drive the top spur gear. This is ideal as the shaft needs rotate anticlockwise the handle will turn clockwise - this is the more natural direction for me. I will fix a threaded stud onto the winder which will pass through a slot in the winder bracket to allow for differing wheel sizes! The handle has two pins which locate in the driving holes in the change wheel for a positive drive.
While I write this I am thinking that to minimise the machining on the coil winder, I can fit a 1.25" boss with the 12mm stud onto the winder using 2 off 2BA screws rather than boring a 12mm hole - much less swarf and more likely to be correct!

Here's the winder I have made:

I have just looked at the flat bit. I would not be inclined to drill into it as when I look at the photo in the previous post there may well be a shaft that terminates in the other side of it.

I have an partly finished winder that is a complete home build.
It is nice to see the photos of a commercial one and I have been quietly mulling over them.

Don't worry, Ref. I know absolutely that there is nothing on the inside of that flat. The guide shaft to which you refer stops at the inner wall of the casting and comes nowhere near the outer wall.

Between the two walls of that casting is the reversing gear for the carrier. The shaft at the front slides sideways to reverse the direction of travel and is operated by adjustable stops on the shaft. These are moved sideways by the travel of the carrier. Thus, when the winding gets to one preset extremity, the carrier pushes against one of the adjustable stops which then reverses the direction of travel. This action is repeated when the other adjustable stop is pushed in the other direction.

Looking at the crank parts and reading on I get the impression you have now chosen to use the existing tapped hole anyway.