Do you feed close to the coil or further away?

[Sheldon Dingwall]

I'm helping my guys de-bug and improve our winding system. I visited one factory after NAMM that feeds the wire quite close to the coil. Our guide is 2-3" away. We're thinking of making an adapter to try moving the guide maybe a foot away from the coil to see if that makes things laydown more predictably or not. Smooths the tension bumps at the ends of the coil or not.

Anyone have any experience to share?

[David Schwab]

My guide is 5.5" away from the bobbin.

[Lyrebird Steve]

Mine is set up about 100mm (4 inches) from the central point (pivot point) of the faceplate

Here's a video at Seymour Duncan .. at about 7:15 in you can see the pickups being wound.
How to Make a Pickup Part 2 - YouTube

Looks pretty close to me

[jason lollar]

the farther away the more randomness is introduced in the way the wire lays. Check out how a sewing machine will wind a bobbin with no traverse just by having the thread guide several inches from the bobbin. This is one way to introduce handwinding variability into an auto winder. I dont know any auto winder than can do what everyone claims they do - laying each turn next to the last- unless you get the traverse guide right up on the bobbin otherwise the wire will start oscillating unpredictably let alone the differences winding oblong coils compared to cylindrical bobbins.

[Bruce Johnson]

I built my winder so that the feed wheel (the last thing the wire touches before it hits the bobbin) is within 1/4" of the bobbin. That keeps the winding much closer to a uniform layer but, like Jason says, it still does a certain amount of random wandering. The closer the feed point is to the bobbin, the narrower the width of the wandering.

I've mentioned it before, but feeding the wire off of a wheel, rather than out of a fixed nozzle, also helps to even out the tension differences on the oblong coils. It's geometry. The point of feed off the wheel rotates back and forth over an arc of the wheel, as the wire feeds from the wheel onto the rotating oblong bobbin. On my machine, I made the feed wheel 2" dia x 0.100" wide with a very narrow V-groove. The wheel spins freely and the traverse mechanism walks it back and forth just outside the radius of the bobbin flanges. That gets me very close to that mythical "single layer feed", which is what I want for the particular pickups that I make.

[Sheldon Dingwall]

I always enjoy your solutions to problems Bruce. Does the guide wheel rotate in the same direction as the coil. I.E. top of the wheel feeds the top of the bobbin or does it counter-rotate feeding the bottom of the bobbin. I'm trying to visualize the physics of how the large diameter wheel pulls the slack out of the oblong coil.

A friend suggested synchronizing a bobbin shaped device 90 degrees out of phase with the bobbin so that as the coil pulls less wire during the rotation the synchronized device takes up the slack. Due to the complications of making that work I've never pursued it.

[Bruce Johnson]

Here are two pictures of my winder, showing the feed wheel winding an oblong bobbin. I've made the wire path short and simple: The spool is tilted up slightly above horizontal; the wire comes off it, goes through the friction tensioner, and goes around the feed wheel about 180 degrees and on to the bobbin.

The reason why this arrangement tends to level out the tension is because there's no increase in friction over the wheel when the wire changes the angle that it's coming off the wheel. That is, as the oblong bobbin rotates, the wire has to sweep up and down, through an angle, to lay down on the bobbin. If you feed the wire out through a nozzle or a hole, then the wire has to bend over the edge of the hole, which causes additional friction and drag. That drag oscillates up and down as the wire sweeps up and down through the angle, and it's much worse the closer you put the nozzle to the bobbin. That's why I went with the wheel; it eliminates that oscillating drag.

It's much more obvious when you get into longer bobbins. I built my machine to handle up to a 6" diameter faceplate. One of the first projects I did on this machine were a couple of 7-string bass pickups with bobbins about 4 1/2" long. It wound them well, without much looseness in the middle.

[David King]

I think a thin, flexible teflon nozzle like those superglue tips with the pipettes might help with the angular issue Bruce brings up. Having the tensioner further away will definitely help even out wire tension and prevent breaks.

[Bruce Johnson]

Yes, a small flexible tube is another way to reduce the angular drag thing. As long as you can figure a way to allow it to flop up and down, but not flop side to side too much. Maybe restrain the tube between two thin vertical plates?

One of the other reasons that I like the wheel as the point of feeding, is that it makes the initial threading up of a bobbin easy. I anchor the wire in the Start hole on the bobbin, then hook it over the wheel, and turn the spindle by hand to take up the slack. No extra hole to thread it through.

This winder has been very reliable. I built it in 2006, and I wind all of the pickups for my basses on it. Since the initial messing around with it, I've hardly ever broken any wire or otherwise ruined a coil with loose loops or anything. I run about 25 gm of tension, and I run the speed between 800 and 1600 rpm. Most of my coils are 5000 or 6000 turns, but I do some round ones that get 12,000 turns. The traverse is a reversing leadscrew type, driven by toothed timing belts (which are a blur in the picture). The traverse rate is fixed at just over 0.002" per revolution of the spindle. It lays the wire down in neat, flat layers without much bulging or flaring. I'm happy with it overall.

It has a couple of minor mechanical problems that I want to fix eventually. But I depend on this machine enough now that I can't have it down for long. I'll probably just build a second one of similar design, but more compact. This one is large and very adjustable, because I wanted to be able to swing long bobbins if necessary. But all of my production pickups these days are smaller sized.

[David King]

Bruce, How are you measuring tension? Does it ever change over time as the felt settles or wears out?

[Bruce Johnson]

I bought a tension gauge on ebay, for about $10. It's a Scherr-Tumico (Made In France) 0-50 gm, one of the small hand-held tension gauges as used by inspectors in textile factories. I got it about 6 years ago, a little while after I built my winder. Just last week, I scored another one on ebay for $2.99 plus shipping. It's a Haldor 0-20 gm gauge, and still has a Rockwell International inspection sticker on it. I don't really need it, but sometime the lower range might come in handy. How could I pass it up for $2.99? The seller didn't really know what it was and had it marked as a Gram Gauge. It probably cost $250 new, thirty or more years ago. It still works fine.

I use silicone rubber in my tensioner, not felt. It's been consistent. I used the tension gauge to adjust the drag to about 25 gm, and I re-check it now and then, like if I haven't used the machine in a month or two. Sometimes I have to tweak it, but most times not. I'm not fussy about the tension, other than wanting it to be consistent on my pickups from one to the next. I chose 25 grams as my nominal because it seems about right. The wire lays down neatly and the coils are snug but not crushed. And I haven't had any problem with breakage.

[Rude Dog]

Silicone Rubber

Would you mind sharing more info about using silicone rubber. Do you "make your own" in a mould, or repurpose from another application?

Thank you.

[Bruce Johnson]

Nothing that fancy. Just two pieces of silicone rubber door weatherstripping, the type that's extruded into a hollow "P" shape with adhesive on the back. I had some here, and it seems to work fine. I haven't had to replace it so far in about 5 years of running. I may make up something a little better later on.

[Sheldon Dingwall]

How are you using the gauge Bruce?

[Bruce Johnson]

Have you seen this style of tension gauges? Here's one on ebay right now (for $10), a Scherr-Tumico just like mine, except this one has a range of 0-150 grams. Mine has a range of 0-50 grams, which is better for our purposes.

Scherr Tomico Tension Force Gauge | eBay

It's like a little dial indicator, with a little metal finger sticking out. You push sideways on the tip of the finger, and it reads how many grams you are pushing, in either direction. To measure the drag of your winders' tensioner, take the end of the wire coming out of the tensioner, and wrap a turn or two around the tip of the finger of the gauge. Then, gently pull the gauge sideways, drawing the wire through the tensioner, and read the force on the gauge. It only takes a few seconds.

Oooooh...Here's a nice 0-30 gram Correx gauge for $25. And they have a couple of them!

http://www.ebay.com/itm/Correx-0-30-...item2c649cf7f3