initial winding attempts

Well, same experience as when I wound a replacement pickup for my Vox Spitfire: many failed attempts to get one success.  I set up my sewing-machine pickup winder, with customized mounting and wire-guides for the big harp pickup.  I found that I had to go agonizingly slowly, to avoid breaking the wire (chalk up several attempts of 50-100 turns each).  Removing failed windings in order to start over got to be a regular chore, so I put a special notch in the side of the bobbin so that I can easily cut away the old windings with a hobby knife.  Good thing I have an ample supply of #42 wire, the waste is non-trivial.

I found that I did not need to hand-feed the wire to spread it over the bobbin.  The bobbin is narrow enough that with just feeding from the centerline, the wire spreads nicely by itself.  Therefore, I was able to set up the machine to run unattended, using a carpentry clamp to set the position of the "accelerator pedal" on the sewing machine.  Since there is no closed loop, the resistive control pedal heats up and the speed changes, so it took a while to get it set to run at the right speed long-term; it would tend to start off slow, but then after a few minutes it would start going catastrophically fast and break the wire.  I got it set to a stable slow speed, which only makes a few turns per minute, but now I can just start it running and leave it, so it will gradually get the job done.  Unless it catches on fire first: the ancient resistive pedal gets scarily hot and makes horrible smells; I don't know if they specced it to run at near-stall speeds for hours at a time.  I wish there was a fuse somewhere in the system, but there's not.  So I've ordered a semiconductor motor speed control...

Finally, I got up to over 300 turns (361 actually).  But I noticed that some of the windings are sloppy, hanging loosely off of one side of the bobbin.  I thought this was due to the somewhat jerky motion of the machine, operating at very slow speeds, but I noticed that in fact it seems to be due to a bad spot on the end of the bobbin, where wire can slip in between the bobbin form and the side flange.  I hope that if I fix that, I can achieve good results with the current setup.  If not, I have the parts on order to make a new winder, based on a stepper motor, which will turn more smoothly.  (Stepper motor, A4988 stepper driver, 555 timer.)

Since 361 turns should be enough to test the pickup, I took it off the machine and attached lead wires and a jack.  I measure about 901 Ohms, or just about 2.5 Ohms per turn (makes sense since the turns are longer than in a guitar pickup).  Time for the first audio test...

...And hooray, I'm happy to report that the test was successful, it makes sound!  Actually, it was almost sensitive enough to use as-is, although I did have to turn up my Fender Champ almost all the way.  So, I hope that around 1000-2000 windings should do the job nicely.  Interestingly, even when I removed the magnets, the coil still picked up some sound from the strings, although not as loudly.  I don't know if some of the steel has become magnetized, or maybe the old harp strings have become magnetized, or my understanding of how pickups work is just faulty.  But anyway, it certainly works better with the magnets present.

(Later:  I have found that indeed, the metal plate was highly magnetized, and this must be why the pickup worked pretty well even without the "official" magnets attached.  I think the very "mild" steel that the VCR case was made from, is probably particularly ferrous or easy to magnetize, being closer to raw iron; as contrasted with tougher types of steel, notably stainless steel and surgical steel, which are virtually non-magnetic.  At least, that's my non-expert guesswork!)