Telsla Coil Secondary Winder build

At last after years of winding tesla coil secondaries by hand I decided to build a more automated winder. Ive not gone down this route before as the coils that I use for my electronic tesla coils are wound with thin wire, usually around 0.125mm.

Be20160805_155807cause of the need for really fine wire winding the build needs to be sturdy. The build is made from 6mm Acrylic from and old sign. held together with M5 bolts angle brackets and studding. The stepper motors for the lead screw and to rotate the coil former 20160809_184816are bolted to this.

The lead screw positions a small trolly with a pulley this has the wire from the spool. As the two stepper 20160809_184828motors can be controlled with variable ratios so different wire widths can be accommodated.20160816_173219

A single shaft parallel to the lead screw stops the trolley from rotating with the lead screw.

The spool is held in a jig that is mounted on top of the winder. The wire passes from this spool to the other end of the winder and then back to the trolley pulley. This long path ensures that the wire feeding in20160809_184823to the pulley  is always at the same angle to the trolley and pulley and therefore should always have the same tension.

The steppers are driven with two A4988 bipolar stepper motor driver boards. Th20160814_220752ese are microstepping drivers capable of 16 steps per step and with the 400 steps per turn resolution from the type 17 steppers and the 4mm p20160814_225412er turn lead screw, this gives me a resolution of 0.001mm per step. Good enough for even the smallest diameter wire.

The steppers are controlled by a Pi3 as this make is really easy to SSH in and cocp1kklxwcaeydz6ntrol the winding.

The control software was written in C and allows the coil former to be spun at a range of speeds and the lead screw to be turned at any division of the former rotation speed.

cpw142bwyaaglsu The Coil former is held in position by a pair of stepped cones. Each of the steps suits a common pipe inner radius, so just by clamping the former between the two automatically centered the former to the shaft.