This is a HOW-TO from a newbie to a newbie, so all you pro's out there bear this in mind :)
Seeing as this is my first attempt at winding a secondary coil I thought it best to practice on something smaller, so of to the kitchen where I found a small tubular aspirin container, that will do nicely I thought. Back in my room I looked despairingly at the bobbin of 0.2mm wire, and with faint heart plus glasses I started to wind. It soon became apparent that even with glasses this would be no easy task. Infact it was impossible to get a tight wind with zero space. OK I know my eyesight isnt 10:10 but seeing that I don't posses 4 hands, things were just not going right. So time to think on the problem at hand, lets see
1. somehow to turn the former at a constant rate
2. something to feed the wire consistently
3. see the turns accurately
4. a way of taking a rest without the windings un doing
OK lets tackle number one, back to the kitchen, for nibble whilst I think. H'm choc-ice be nice, 10seconds each side then 6 to finish, in microwave. Watchin me choc-ice revolve around in the microwave it occurred to me that No.1 may have been sorted. Quick phone call to a microwave oven repair shop confirmed that. Dash out, rush back and in my hand 2 small 240v AC 5/20 rpm motors and at no charge, such a nice guy. One problem sorted, and a new one found, need something to mount this on. More thinking time and a cup of caffeine.....
So my first coil is kinda small, but hopefully the 2nd will be larger, with that in mind I rummage in the garage for bits of wood. H'm nice covered chipboard, 6" wide 6ft long and another piece 2" wide 6ft long, that will do nicely. So assuming chippy mode I measure out 3ft on the 6" wide stuff and 2 3ft on the 2" wide stuff. Next I glue/screw the 2" to either side of the 6" forming a long 'U' shape. Next I cut 2 8" lengths from the 6" bit and fasten one to the end of my 'U'. The other is a tight fit in the middle of the 'U' section. Then I mount the motor with on/off switch to the fixed section and drill a small hole in the other section so that it aligns up with the centre of the motor shaft. You'll see why shortly :)
Next problem is coupling the motor shaft to the coil former, so thinks time again.... Fumbling around I came across some co-ax shrouds that fit on BNC plugs giving you cable support, ok u might not have them so a piece of tube suitable size would do just as well. Next I get a gland (type used in electrical cabinets), (or cut down the neck of a plastic bottle) you got to improvise here :) Object being is to find something that 'a' will fit inside the former and 'b' will connect to the motor shaft.
With these 2 parts I push the shroud through the hole and onto the motor shaft, then slide onto the shroud the plastic gland. Grabbing the coil former I notice one end sealed, into this I make a small hole, pin size, (to be sealed later) and push a needle into it, the other end fits in the movable bit of wood, then slide the open end onto the gland and he presto its support and turns at a constant rate. One good thing is because they are all push fits, they act as a slipping clutch, so they wont stress the wire if I hold it to tight.
Prob 1 sorted :)
No2. Looking around again I find a small card index plastic box about 6x4x4" removing the lid I drill a hole .5" in each side center 1" from the top. next a cut up a bit of dowel (or cane) 8" long and on each end .25" in drill a small hole. Taking the bobbin I hold it in the box and push the dowel thru one hole, thru the bobbin and then the other hole, next 2 paper clips pushed in the little holes of the dowel secure it in position. Now the bobbin spins easily, too easy in fact, we need friction, another rummage finds some foam rubber cut to side and pushed infront of the bobbin provides enough friction to hold the bobbin steady, Mod, I placed some thin polythene sheet in front of the foam to give a smoother feed motion. Prob 2. sorted.
Prob 3 is no real problem, I have a desk top magnifier :) Waddling back to my room I commence to set up my new toys, the former turns nicely all be it slow at 5rpm but for first time I'll stick with this speed. Taping the wire to one end and using finger and thumb to guide it I commence to 'coil'. Disaster, the wire is so small I seem to have problems getting a tight winding, Did notice one thing, if u switch the motor on/off/on fast it reverses its direction, nice for going back. And the friction on the bobbin prevents the wire loosing when u switch motor off. Another search revels a small piece of fibre glass board about 2mm thick (cardboard would do just as well). With this I fire up the motor once again, only this time I gentle tap the wire on the former to get a tight wind. I found that guiding the wire about 1-2 degrees from vertical allows me great control and the tapping stick gently nudges it into place, also you don't have to worry if u miss a bit as you can get it on the next revolution. Only one thing I need now, well two actually, caffeine and music :) then of we go....... easy peasy :)
ps btw I dropped of a bottle of scotch at the microwave shop, now he's a happy chappy.... :) BellaDonna