Coil Winding Machine
Coil Winding Machine
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Winding thousands of turns of extremely thin wire by hand is not a fun task, especially when the coil you are working on is too big to hold in your hand. To assist me in winding the coils for my DRSSTC and SGTC, I built a winding machine out of stuff I had laying around and an extra stepper motor I had from my 3D printer.
Winding thousands of turns of extremely thin wire by hand is not a fun task, especially when the coil you are working on is too big to hold in your hand. To assist me in winding the coils for my DRSSTC and SGTC, I built a winding machine out of stuff I had laying around and an extra stepper motor I had from my 3D printer.
This is the first version of my winder. I got a few 8mm steel rods which I joined together using 3D printed connectors to make a shaft. On the right side of the photo is a NEMA 17 stepper motor in a vise. I powered it using an Arduino development board triggering an L298N motor driver. The left side is just an upright block of wood with a bearing. To mount the pipe, I first hot glued a piece of wood across the diameter of each side. I drew two secant lines on each, and found the perpendicular bisector of them. Continuing these bisectors revealed the center of the pipe where they met.
This is the first version of my winder. I got a few 8mm steel rods which I joined together using 3D printed connectors to make a shaft. On the right side of the photo is a NEMA 17 stepper motor in a vise. I powered it using an Arduino development board triggering an L298N motor driver. The left side is just an upright block of wood with a bearing. To mount the pipe, I first hot glued a piece of wood across the diameter of each side. I drew two secant lines on each, and found the perpendicular bisector of them. Continuing these bisectors revealed the center of the pipe where they met.
On the chair is a roll of 30 AWG enameled copper wire, more commonly known as magnet wire. For this first winder, I didn't have a spool holder, so I just used the box it came in.
On the chair is a roll of 30 AWG enameled copper wire, more commonly known as magnet wire. For this first winder, I didn't have a spool holder, so I just used the box it came in.
Normally, I say "this worked, even though it is not the best." For this winder, however, saying it worked would be a stretch. The winder was hard to control from my computer while winding, and the joints I made either slipped off or broke. The way I printed them put nearly all of the force on the strength of layer-to-layer adhesion. Thus, no matter what percent infill I set, the part would not be able to stay together.
Normally, I say "this worked, even though it is not the best." For this winder, however, saying it worked would be a stretch. The winder was hard to control from my computer while winding, and the joints I made either slipped off or broke. The way I printed them put nearly all of the force on the strength of layer-to-layer adhesion. Thus, no matter what percent infill I set, the part would not be able to stay together.
In addition to this, the rig was stuck in my basement, which is the least ideal place to cure varnish or epoxy. Varnishes have volatile organic compounds which evolve into the surrounding area. Having the varnish cure in a well ventilated area is key to, well, not inhaling carcinogens. I had a tradeoff with this first coil: I could quickly coat it and move it to the garage, but I would not be able to spin it while curing, leaving uneven marks and droplets. Or I could spin it in the basement. I went with the latter, opening two tiny windows to the outside air. I put up a few fans to try and increase ventilation.
In addition to this, the rig was stuck in my basement, which is the least ideal place to cure varnish or epoxy. Varnishes have volatile organic compounds which evolve into the surrounding area. Having the varnish cure in a well ventilated area is key to, well, not inhaling carcinogens. I had a tradeoff with this first coil: I could quickly coat it and move it to the garage, but I would not be able to spin it while curing, leaving uneven marks and droplets. Or I could spin it in the basement. I went with the latter, opening two tiny windows to the outside air. I put up a few fans to try and increase ventilation.
I knew I had to upgrade if I wanted to keep my sanity while winding and produce high quality coils. I needed something that was robust and portable. This is what I came up with:
I knew I had to upgrade if I wanted to keep my sanity while winding and produce high quality coils. I needed something that was robust and portable. This is what I came up with:
It's just a long piece of wood separating a 2x4 with the stepper motor and the support block on the other side. For the control circuit, I added a start/stop switch which can stop the spinning and a potentiometer which controls speed. I programmed it to go anywhere from 2-100 RPM.
It's just a long piece of wood separating a 2x4 with the stepper motor and the support block on the other side. For the control circuit, I added a start/stop switch which can stop the spinning and a potentiometer which controls speed. I programmed it to go anywhere from 2-100 RPM.
This is what turns the wheels. Or rather, the pipe. I scrapped the metal rods I had for a 2' long x 1/2" wide dowel. This was a much better choice, as having as few weak points as possible is ideal.
This is what turns the wheels. Or rather, the pipe. I scrapped the metal rods I had for a 2' long x 1/2" wide dowel. This was a much better choice, as having as few weak points as possible is ideal.
There are two 3D printed pieces I designed. One connects the stepper motor to the 'give' system, and the other to the dowel. It just so happened that I realized one of my previous joints nearly fit inside a piece of PVC, which gave me an idea. If I made the joint small enough to fit inside 1/2" PVC, I had solved my problem with them breaking (2nd piece is 3/4" for the dowel). The part in between the two joints is a 100mm steel rod. I did end up keeping just one, as the dowel I had simply wasn't long enough. A benefit of it, however, is that it acts like a spring, dampening sudden movements. It's completely covered in hot glue from side to side. The rod provides support, while the glue provides the twisting.
There are two 3D printed pieces I designed. One connects the stepper motor to the 'give' system, and the other to the dowel. It just so happened that I realized one of my previous joints nearly fit inside a piece of PVC, which gave me an idea. If I made the joint small enough to fit inside 1/2" PVC, I had solved my problem with them breaking (2nd piece is 3/4" for the dowel). The part in between the two joints is a 100mm steel rod. I did end up keeping just one, as the dowel I had simply wasn't long enough. A benefit of it, however, is that it acts like a spring, dampening sudden movements. It's completely covered in hot glue from side to side. The rod provides support, while the glue provides the twisting.
The final benefit of the new rig is its portability. I was able to coat the secondary for my spark gap Tesla coil in clear epoxy, giving it a crystal clear, see-yourself-in-it, rock hard finish.
The final benefit of the new rig is its portability. I was able to coat the secondary for my spark gap Tesla coil in clear epoxy, giving it a crystal clear, see-yourself-in-it, rock hard finish.
Version 3
Version 3
When I was tasked with making a Tesla Coil for WPI, I had to remake the winder. The stepper motor simply didn't have enough torque to rotate the four feet of 6" PVC I planned to use. Mechanical engineering is definitely not my strong suit, but I feel that my effort in making the new version paid off.
When I was tasked with making a Tesla Coil for WPI, I had to remake the winder. The stepper motor simply didn't have enough torque to rotate the four feet of 6" PVC I planned to use. Mechanical engineering is definitely not my strong suit, but I feel that my effort in making the new version paid off.
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