Do you feed close to the coil or further away?

[David King]

Thanks Bruce,
That's what I figured but I wasn't sure. There another type of tension meter that has three coplanar wheels in a triangle formation. The middle wheel is connected to the needle while the outer two are connected to a lever which allows you to clamp it on to a moving wire and take a "live" reading.

There seem to be pages and pages of these things for sale on ebay. They must have been in wide scale use in the fabric or cotton processing industry?

[Sheldon Dingwall]

Thanks Bruce, that was simpler than I thought. I feel kind of dumb now

[Bruce Johnson]

These little gauges of the type that I showed you are officially called Force Gauges, because they actually measure force. They read out how many grams or ounces of force are being applied to the side of the tip of the finger. They are commonly called Tension Gauges, because they are usually used to test or measure a small amount of tension in a fine thread or wire. They are used a lot in the textile industry, for adjusting drag rollers and things in automated looms. They are also used in the electronics and electric components industry, wherever little coils are wound from fine wire, such as teeny electric motors. I've also seen them used in aerospace inspection labs, for pull testing wire harness connections. These days, of course, most of those jobs are done with digital electronic force gauges, which can send their data over a wire to a computer. So these little mechanical gauges are outdated technology, being sold for cheap on ebay. But they still work.

Yeah, those three-wheel tension gauges will allow you to read the tension "live" while the wire is passing through. But that seems like way more hassle than it's worth. At the low tension levels that we run at, trying to get one of those to run reliably and not complicate the winders' operation, doesn't seem worth it.

A little time spent pulling wire through your tensioner, and reading the tension with one of these force gauges will tell you how consistent your tensioner is. If it isn't easily adjustable and reasonably consistent, then you need to work on it.

[David King]

What about just taping a 25g weight to the end of your wire and adjusting the tensioner until it just stops dropping?

[kayakerca]

I

What about just taping a 25g weight to the end of your wire and adjusting the tensioner until it just stops dropping?

I just drag the wire through tied to the end of the meter arm and adjust the tensioner until the tension meter reads where I want the tension to be.

[Bruce Johnson]

Well, sure, you can measure force with little weights too. That's the really old-fashioned way! I usually try to keep my technology between 25 and 100 years old. Well proven, but not completely obsolete. And cheap on ebay.

Actually, you need to think back to your Physics classes (oh nooooo..) and remember the difference between Static Friction and Dynamic Friction. They are indeed different. We want our wire tensioners to control the Dynamic Friction, which is the friction that you get while the two materials are sliding against each other at constant speed. So, you need to use the weights or force gauge to measure the drag while the wire is in motion through the tensioner. If you adjust the tensioner so that the 25gm weight just stops moving (or the Force Gauge reads 25gm as the wire just begins to move), then you are adjusting the Static Friction. We don't really care about that, because it only determines the tension in the wire during the split-second that the winder just begins to turn. As soon as the wire is sliding, it's in Dynamic Friction. For most materials, the Dynamic Friction is about 1/2 to 2/3 of the Static Friction. If you adjust the Static Friction to 25gm, the Dynamic Friction will be 12-15gm. If you have a Force Gauge, you can play around with it and see for yourself. As you gently begin pulling on the gauge, the needle will spike to a higher number just before the wire breaks free. That's the Force/Tension caused by the Static Friction. As you continue pulling and the wire slides through the tensioner, the needle will settle to a lower number. That's the Force/Tension from Dynamic Friction, which is what you really care about as a pickup winder.

It's embarrassing to admit that when I took Physics in High School, we actually used slide rules. That's probably related to my obsession with old technology.

[ReWind]

That's a very innovative winder, Bruce. I like your traverse. I think I see what's going on there.

Would a flexible feeder nozzle not heat up and soften, creating drag? I'm using both pulleys and syringe nozzles now, but have some fancier nozzles on the way. I haven't noticed a difference in sonic qualities between the two. I don't point the nozzles at the center of the rotating shaft, as I've read elsewhere, but rather at the center of wire travel between low and high points - so about 3/4 of the way up the bobbin when it's sitting vertical.

btw - it looks like you're winding on a trem block, instead of a bobbin, in that first shot, Bruce.

[Bruce Johnson]

Thanks, ReWind!

Here's an old thread from 2008, which describes how my winder works in more detail:

http://music-electronics-forum.com/t10612/

The bobbin being wound in that picture is cast from polyurethane, tinted grey. That's an old picture. These days I cast my bobbins from pre-mixed black polyurethane resin.

If you haven't seen it before, here's a series of pages showing the whole process of how I make the pickups for my Series IV Scroll Basses. Those are actually obsolete now; I stopped making that model in 2011. I need to update that whole section to show my current models. It's pretty much the same process.

Building Scroll Basses- Pickups 1

[Sheldon Dingwall]

A big thank you to Bruce for suggesting the Force Gauge. Picked one up and immediately found that our tension was oscillating. Found and fixed that issue and things are winding smoothly now.

[Bruce Johnson]

Let the Force Gauge be with you!