Two humbucker coils. One wound with 5720 turns and the other wound with 5600 turns. Same speed, tpl and tension. But the coil with less turns has a higher resistance and the one with more turns has a lower resistance, 4.40 and 4.23 respectively.
All that is left is mechanical aberration, correct? Or am I not thinking of something?
Internal shorts would be the most likely answer followed by stretching.
Temperature is very relevant here too -you can watch the resistance change just while you hold the coil in a warm hand.
It could also be smaller wire OD on the one with higher DC resistance...this can happen even on the same spool. Mic the OD of the two coils at both start & finish to see if wire OD could be the culprit.
Are you machine winding with auto-traverse or hand guiding your wire?
If hand guided, TPLs could be slightly off causing your situation. This would be hard to tell because your off-set is so little. Generally a lower TPL will generate a bigger coil with higher DC resistance even with the same turn count.
Last edited by Jim Darr; 02-20-2017 at 02:46 AM.
Keep Winding...Keep Playing!!!
What kind of circuit is the turns counter? Some mechanical ones(reed switches, lever switch) screw up or bounce.
If anything it's a tension issue or wavering somewhere in the traverse mechanism.
However, after posting this earlier, I've since wound a dozen sets of coils. Everything seems fine...fingers crossed.
It's still bothersome, though.
All posts have good insights and considerations. Temp, humidity...2 big variables. Small changes make a difference. I've had - and I think we've all had - similar experiences at points in our career and probably still do from time to time: this is good stuff, really. When in doubt, start again. Customers deserve our absolute best, period!
And yes, lots of good stuff and online to always have and for others to learn from.
If it's possible that the counter may be counting wrong ,a small jeweler scale can easily weight the different weight of the coils .
"UP here in the Canada we shoot things we don't understand"
5720/5600 = 2% difference in resistance
(5720/5600)^2 = 4% difference in inductance
Experience is something you get, just after you really needed it.
If I have an inductance of, say, 1.5 (or whatever) in the larger coil the difference between the two would be .06 or so. So if I have my meter on a less sensitive selection it probably wouldn't show a big difference or any difference.
If the inductance is equal then the number of loops should be the same. That leaves the resistance difference to wire manufacture variations. Many variables that could cause the wire to be slightly thicker/thinner along its whole length at the tiny diameter of pickup wires, mechanical and chemistry both.
I remember something about steel sheet rolling will have thinner ends and thicker center because it starts out as a thick block and gets squeezed out and stretched. There was even a term for it but it escapes me at the moment. Point is the spool you have could have been thick or thin size at the beginning and changed along the five miles of wire spread across those pickups. Wouldn't take much that wire manufacturing thickness gages could barely discern but have enough of it and the resistance changes.
Might plot out which pickup was done first, readings vs length and any you wind in sequence after. Maybe see a rising/falling trend in the order built.
Knowing exactly how wire is made would be instructive here. Anyone care to expound on the finer points of drawing copper through dies?
The first video below doesn't dwell on the wire resizing operation, but the second one does. See the surging of the continuous sizing machine farther in the second video. Those stages with rows of opposing offset wheels are there to straighten the wire. All of the resizing, the gripping, and the straightening operations work harden the material which will alter how it stretches in later operations. Tension on the wire-making take-up spools could even change the wire as wound from the spool inner diameter to the outer large diameter as the circumference of the spool changes the take-up speed. Annealing furnace variations can alter the draw process. The third video gets closer to pickup wire manufacture. Everything that is touching that wire the whole way through can be a variable on the output.
This is all not including the wire chemistry to start with. New from the ground copper vs reclaimed copper. Some copper mines have higher contents of other alloying materials already in the copper at some acceptable level of 'contamination', but it's all a variation.
At least remember that guitar potentiometers have a 20% tolerance band of acceptable factory variation and better tone caps have 5% tolerance. I have seen a 5% DCR reading across a three pickup Strat set.
OP's two bobbins, assuming aiming for the same number of winds, are 2% off each other and the resistance variation is 4%, while a low sample, is a lower tolerance than the circuits that gate the pickup tone into the amp.
I have often been curious what the output variation is of bigger pickup manufacturers like Fender/Gibson/Duncan/etc daily and over weeks, partly due to my interest in guitars but also on the day job side I'm involved with manufacturing (automotive). What wacky shenanigans go on in their plants?
If you combine some of the answers?
Are the bobbins the same (height, width, flange)?
Do both coils weigh the same?
Mic the outside diameter of the 2 coils, are they the same diameter?
If you answer no to any of the above, then the two bobbins are not wound the same and will read differently!
Technicians Run the World, but Bankers, Lawyers, and Accountants, Take All The Credit!
Keep Rockin! B_T
Just one of the MYSTERIES OF WINDING PICKUPS
"UP here in the Canada we shoot things we don't understand"
Pickups are as variable as people, and you will never wind two coils exactly alike. And even if you managed to do it... they would probably sound completely different from each other. The trick is not to obsess over the numbers, but to obsess over the sound
Obviously every pickup made isn't being put in a guitar first and played. The best 'I' have to go with are subject limits of anomaly that tell me a given coil or pickup shouldn't be sent out.
Pickups are made of of a collection of parts made by humans, all with different tolerance levels for the parts they themselves make. In other words, somebody who is tired on Friday afternoon after lasering bobbin flats all day and wants to go home is not going to be as fussy about the parts they made as I would be, because I'm OCD about pickups and make my own parts. Each part you add to your pickup adds its own set of variables to the finished piece, and sometimes the accrued tolerances can really mess you up.
I have found the best way to deal with the problem is to test *each step* in your process after you do it.
Assembled your bobbin? Measure it with calipers and make sure the magnets are correct and tight before you wind the coil. Wound your coil? Make sure your coil is complete and not shorted or open before you pot the pickup or wrap it in tape. Wrapped or potted the coil? Check it again. Did the measurements you get this time change from the ones you took after winding? Why?
This will teach you how each step in your process can change your finished product, and can help you find what exactly went wrong. Besides, the info you will generate will give you an education in pickup making you won't get on YouTube.
Yes... I test every pickup I make in a guitar before I send it out as part of final inspection. How are you going to know if you have a defective product if you don't test it?
Canīt believe we have reached more than 30 answers wondering about unimportant differences (IF there is any audible one, that is) between 2 handwound pickups, on a homemade machine, within 10% (or less) from each other, and based on a grand total sample of 2 (two).
Juan Manuel Fahey
I have a 5S7 (1957 Strat style) pickup in my collection I made years ago. It looks perfect, it electrically tests perfectly, but for some weird reason it has a strange fizzy distortion product when played loud I can see on my scope. Play it soft, it's fine. Problem is I can't figure out why it did it, and it was the only one I ever made that did that. I keep it as a reminder to test everything before it leaves here whether it needs it or not.I think electrical tests would be sufficient to pick up problems in production of the same pickup model.
The only explanation I can think of is some kind of insulation issue on the coil wire. Like I said, it's electrically perfect.
Last edited by ken; 03-06-2017 at 05:14 AM.
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