Thread: Coil Winder Project

Don't know if this qualifies as metalwork project but it does have some aspects of metal work in it so I'll post it anyway as some might be interested. I wanted a coil winder for over 10yrs and always planned to build one using a picaxe - I had grand plans an LCD readout, enter the wire diameter, width of the bobbin, number of turns and away it would go. Fast forward 10 yrs and I finally made a start but soon realised my grand plans had to scaled back to not so grand and then eventually settled for what I have in the video. I wasn't sure how it would work out so I decided to make do with as much I could and purchase as little as possible, the drive spindle is an old belt driven grinding/polishing spindle driven by a 12v car radiator fan motor powered by a stand alone PWM speed controller. This is in turn controlled by a picaxe 18m2+ chip via a relay. The turns counter (not very clear in the video as I still need to mount a green filter over the LED's) is also stand alone cmos type 4 digit counter with clock pulses sent from the picaxe. Controls are stop/start via the toggle switch or foot switch speed control, counter reset and a 4 digit thumb wheel switch that allows a certain number of turns to be set and counted up to

Traverse mechanism has left and right jog, a 3 digit thumb wheel switch to set the step distance per revolution and a toggle switch that tells the traverse to stop and the end of each layer so insulation can be added prior to the new layer being wound, the third push button restarts if this is selected, the same thing can be achieved by simply stopping the motor. A second 18m2+ picaxe controls the stepper motor salved from an old dot matrix printer via one of the stepper motor driver modules available on Ebay . There are 3 control wires to allow the picaxe chips to "talk to" each other.

The wire feeder is a copy from a Douglas coil winder that dates back to the 1940's, the shaft that carries the wire spool runs on 2 ball races (salved from an old treadmill) a "drum" on the spool side has 2 spring loaded brakes one above and one below - the top brake is a static brake and the top thumb wheel adjustment is used to lift or lower the brake shoe this adjusts the drag and so the winding tension. The bottom brake shoe is pulled away from the drum by the spring loaded arm and cam - this is in effect an overrun brake so when winding stops the spring loaded arm returns to the upright position and the bottom brake is applied.

Operation is quite simple and probably much better than my original grand plans. A bobbin/coil former is setup in the chuck, the wire being wound is measured and using .02mm as the step distance the number of steps per revolution is set on the 3 digit thumb wheel switch, the traverse distance is set up with 2 micro switches (still need to devise a form of micro adjustment here), pressing both jog button together then sets the traverse step distance, the jog buttons are used to position the start of the wind. The motor start toggle switch then starts the motor and and the traverse advances at each rev of the spindle. The motor can be stopped any time and the spindle hand cranked - traverse will still continue at each rev of the spindle. The jog buttons can be using while winding and the step distance can be reset if needed. If a set number of turns are needed then this can be set on the motor unit thumb wheel switch and the large red button starts the motor which will not stop until the turns count is reached.

It is possible to wind layer after layer with each turn perfectly next to its neighbour, however for this to happen the preceding layer must perfectly flat and even and as the diameter of the wire goes down it becomes harder to manage this so the best way to do this as in a transformer is to use insulation between layers - it is not really that important if using a bobbin which has cheeks but if just winding on a former with no cheeks then the insulation between layers is a must.

Youtube link https://www.youtube.com/watch?v=tAI0hV2tqJ4 this video shows a power supply smoothing choke being wound for a guitar amp project I'm working

Its a little beauty m8, I want one of these now even tho I don't wind coils

cheers, shed

Nice work. I got into programming picaxes a few years back. Its amazing what can be done and how much memory they have. I always thought it was a great compiler that gave good flexibility yet was still a high level progammer making the language easy to learn.

Cheers & thanks for sharing.

Simon

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