Hi there,
About two weeks ago, progress on my current engine project practically stopped when the motor on my bigger lathe died (well, actually my Dad's lathe...). While I was waiting for spare parts (which ended up being a whole new motor), I started playing around with the ignition system for the engine and built a simple ignition circuit that is triggered by a hall effect switch. I have only tested this board with a battery and multimeter, but it seems to be working as it should.
The next obvious question was "what coil am I going to use"? I didn't want to use automotive parts, because of the size, so that left model coils. These coils generally sell for around US$45, which isn't too bad, but since I had the time to waste, I started looking into what it would take to wind my own. For US$45 worth of copper wire, I can probably make several coils anyway. After a fair bit of reading and a combination of rough sketches and CAD drawings, I started to build a coil winder. The only coil winder information and pictures I could find on the internet were for guitar pickups (which apparently don't require 'orderly' winding, while ignition coils do), so the majority of my winder is designed and built the way I think it should be.
I thought about using 2 stepper motors as has been suggested before, but without readily available software (which would take a while for me to write and debug) and the added cost of the steppers and drivers, I decided to go the good old-fashioned mechanical route. The winder is human-powered - hence the crank handle. I will only be winding the secondary coil on this machine (about 15000 turns
), as the primary coil can easily be wound by hand (only about 200 turns).
I designed the gearing so that the ratio can be changed if necessary, however this would obviously require more gears to be machined and it is currently set for the wire size that I plan to use. The mesh is fully adjustable on all but one gear so that it can be setup 'just right' and reset for different size gears. I also included a 'simple' reverse mechanism for the leadscrew.
As you can see in the photos, there is still a bit more work left to do until I can test it, but most of the hard stuff is out of the way. I still need to make the second centre, the wire tensioner (which has potential to be troublesome to set up properly), as well as the wire guide. Hopefully I'll be able to do a bit more on it tomorrow.
Once the winder is finished, I will probably get to go through a steep learning curve on coil winding. Should be fun!
Regards
Warren