potting and inductance

[David Schwab]

Of course you'll have to babysit, no matter what you use. Look at the video of Gibson girls winding pickups, they have to sit there and watch the whole thing. A tiny fraction of a 1/1000th of an inch difference on end stops after a couple thousand winds you can end up with the coil all piled up on one end, you have to check your setup each coil you wind. You can't really automate tension because all tensioners drift, and most of them can't handle oblong coils. So you have to check tension during the wind. My traverse isn't linked and personally wouldn't want it to be, you make things too "perfect" and you end up with tones good enough to clone cheap offshore products ;-)

Well I'm not going to leave the room or anything. Were the Gibsons girls using a CNC setup?

I'm building the Elepro CNC winder, and he even has randomization settings in there. Of course I'll have to figure out what works for my pickups as far as parameters. I'm sure I can get it less than perfect if that's needed. But I wont know what's needed until I try winding with it.

[Rick Turner]

I wind pickups as a part of how I make my living. It's hard enough to do without making it more time consuming than it already is. While my vintage CoWeCo bobbin winder is clattering away, I can be out in my shop making guitar necks, bodies, or spraying instruments, or whatever. I have the same attitude re. my CNC machine which I truly love for what it can do.

That said, I can make just about any part of a guitar from neck to body to hardware virtually by hand, and I've done so, but I don't have the luxury of being a hobbyist at this time in my life. For me it's a way to help support my youngest kid and myself and so I use what I consider the best methods I can afford. I don't think that there is anything inherently superior about doing certain tasks by hand. I don't fell trees by hand, I don't resaw wood by hand, and I no longer use hacksaws and hand files to make brass hardware...I use a milling machine. I don't hand make flatwork for my pickups, I saw it out on a table saw.

As far as pickups go, my own desire is to design to taste...my taste...and then to be able to reproduce those results accurately from day to day, week to week, month to month, and year to year. That's what my customers expect of me. When someone wants to buy a Model 1 or Model T or Electroline bass from me, they are expecting a certain sound from the magnetic pickups I wind for those instruments. I don't care to be chained to the pickup making bench to achieve those consistent results. Hence I use my CoWeCo winder which is automatic and stops at exactly two turns over whatever I set it to. My tensioning device is good enough to hold plus or minus 5% on any run of coils which allows me to match DCR of coils to within + or - 2% (which Joe Gwinn assures me is totally unnecessary). What I get is the sound I designed into the pickup reproduced more accurately than I probably need time after time with minimal effort on my part.

I'm making about 12 of my humbuckers a month this way, and runs of a dozen or so horseshoe pickups at a time, and then the odd run of bass pickups. When I do hand wind, it's for really difficult wire like the Litz wire low Z pickups where the stuff is nearly impossible to run through my tension device, and I have to finger tension and guide.

[Bruce Johnson]

I agree. My winder isn't CNC, but it's a linear mechanical feed with automatic reversing and limit stops. It lays down nice even layers, but still, I have to "bump" it a little bit here and there during the wind to make sure the windings lay in there the way I want. I do this by tapping the limit switches with my finger, essentially making a short partial layer to build up a low area. So, there's a little bit of "hand winding" in there. The next time I upgrade my machine (or build a better one) I'm going to build in a pair of push button "bump" switches just for that purpose. They would just be wired in parallel to the limit switches. If I were building a CNC machine, I'd build in a similar pair of switches or some kind of an instant override so that you could manually tune the coil shape on the fly.

[JGundry]

If you are using an old winder part of the key to getting good repeatable coils of any coil shape is having two felt tensioners. One near the spool and one near the wire guide. You still have to check it from coil to coil but the two felts regulate the tension pretty well. Most of these old machines were set up like this.

[Possum]

My CNC is so low tech, if the wire is piling up on one side I simply tilt the drive and it moves the whole pattern over a notch, no need to tweak the program or anything complicated. What does "random" mean in a program? You won't get the same wind each time? I don't see the use of that personally. I'm sure that controller/winder will be cool, but I don't think it would be something I would trust my livelihood to. If it breaks or fouls up, that means lost money, down time. This isn't a hobby for me and really never was, not even from day one; I told Jason I was going to do this as a business and he gave me untold amounts of help in getting up and running, at least the mechanics of it, I had to figure the tones and skills out for myself. The setup I'm using is so cheap I built two of them so always have a backup, and even a backup PC in case anything happens. So far, its been running for 3 years and not a hitch. I don't like to have too perfect control over tension, I think one of the charms of vintage pickups were they weren't consistent in tension at all, plain enamel especially wears tracks in felt pretty quickly so you have to check it often.

[Joe Gwinn]

Do I have to feed him too? Dave, what do you want to drink?

The whole joy of automation is the elimination of noisy, demanding humans.

The nirvana is lights-out operation: no humans, so no need to turn the lights on. Just the quiet hum and clatter as pickup after pickup lands in the shipping carton. In the morning, drive the carton to the post office for delivery to customers. In the afternoon, deposit the checks.

I suspect that Dave wants his severance in beer.

[JGundry]

I think one thing people miss is that vintage winding machines were often stacked with bobbins. Each bobbin would have its own wire guide and tension adjustments. What people interpret as inconsistent winding machines that need to be monitored through the wind were in fact fairly consistent but set up for each bobbin in the stack varied. Trying to duplicate this with a single bobbin winder is a pain and not very repeatable. The old machines have quirks in the way they wind but they are consistent in how they wind these quirks into the coil. Interesting one machine used for vintage Gibson pickups varies in TPL from machine to machine even if they are set to the same TPL. This is due to a non geared traverse in which the coupling driver wheel wears and slips with time. Thankfully it is easy to mimic with one machine by turning the TPL adjustment crank.

[David Schwab]

What does "random" mean in a program? You won't get the same wind each time? I don't see the use of that personally.

That would simulate hand scatter winding, which is random.

I haven't read Elepro's instructions in a while, but it can do different things to stop it from being an perfectly even machine wound coil.

[Possum]

Yeah I don't buy that, hand winding isn't really "random." He told me you could put in two TPL's for the winder to vary from, well thats not really random either. The way I program for hand winding is by setting enough lines of code to make sure each pass isn't quite the same as the last pass nor the same as any other, then write enough lines so that you build up thickness in the coil so it doesn't matter if they start repeating over again; it works and is real close to hand winding that you can't tell the difference. Its actually much easier to mimic a vintage machine on a single bobbin winder with programming because you are free to create any kind of pattern or quirk you want to. With CNC you tell the traverse to pass at once speed, or pass at varying speeds and stops, there is no limit to what you can do. You don't even need to program these in, just move the wire feed further away from the bobbin and it will start varying from from you told it to do. You can do that with hand winding too, feed the wire from further back and it will start to guide itself onto the bobbin.

[David Schwab]

Hand winding is random because you can't exactly repeat it.

I try not to do a hand winding pattern anyway. I stick to roughly the same TPL and go from there. I try to be as neat as possible.

[-Elepro-]

with my controller you can have 3 modes:

- a fixed setted tpl in all layer

- random tpl between 2 setted values

- from 2 to 10 setted values that you can rotate through layers

...read manual in my signature....

if the wire is piling up on one side I simply tilt the drive and it moves the whole pattern over a notch, no need to tweak the program or anything complicated

exactly like mine.... i can modify limit switch position while running.... watch picture...

instead, can you set faceplate speed perfectly? if no with same program you will have different TPLs... this is for me an unwanted random mode...
bye

[J M Fahey]

Hey, thanks a lot for an excellent posting.
Impressive work, thanks for sharing.
I'm interested in winding real small (microphone/line out/interstage) transformers; your idea is very good, and , to boot , exists in the flesh (well, plastic/metal), not as a drawing on a napkin.
Thanks.
PS: My old tired '56 vintage transformer winder, in theory can do that, but in practice not, because "play" can be reduced but not fully eliminated.

[Rick Turner]

Am I getting this right? Is this CNC traverse NOT linked to RPM, but is independent? That would be a problem, I would think. Or not a problem if you like quasi-randomness. But you should at least be able to link traverse to RPM if you want to wind identical coils time after time. And why would you not at least be able to wind identical coils? I keep coming back to the idea of being able to find "your sound" and repeat it.

[-Elepro-]

Am I getting this right? Is this CNC traverse NOT linked to RPM, but is independent?

mine is perfectly in syncro.... and also if it's in random mode display show TPL values chosen at random

[David Schwab]

Am I getting this right? Is this CNC traverse NOT linked to RPM, but is independent?

That would be Possum's machine, not Elepro's.