Tension gauge use question

[larams]

Hey guys, I got a hold of this little tension gauge made by mecmesin. It looks like the one in the picture except it has a 0 - 50 gram scale.



How should I be using this to check my wire tension? Would wrapping the wire around the stem part and pulling the wire while looking at the tension work or is it supposed to press down on the wire when it's stretched out?

[Bruce Johnson]

Yes, that's the right kind of tension gauge, and the right measuring range. It measures tension by the side-to-side movement of the tip of the lever. Hold it in your hand and gently push sideways on the tip, and you'll see how it works. Note how the dial goes 0-50gm to the right and to the left.

To use it, pull a bit of wire out from your friction washer device and wrap a couple of turns around the tip of the arm. Hold the gauge so the arm is perpendicular to the wire and pull the gauge sideways slowly. While it's moving, read the tension on the dial.

If you remember your Physics, there is Static Friction and Dynamic Friction. When you begin pulling on the gauge, there will be a quick pulse of a higher tension number. That's the Static Friction, the force required to get the wire moving from sitting still. For pickup winding, you don't care about that. What you care about is Dynamic Friction, which is the tension/drag/force on the wire, while the wire is being pulled out at constant speed. You want the tension reading while you are in motion, pulling the gauge.

I run the tension on my machine at 25 gm, using #41 wire. I think most of us winders run in the 15-25 gm range. That's about the right range for the wires that we normally use, #40-#44. You'll probably find that the breaking point of the wire is up around 40-50 gm. Experiment and test it if you like.

The main use of these gauges is for consistency. These little gauges are pretty accurate, but it doesn't matter so much what tension value you use. Find what works for you and use the gauge to check it now and then to make sure it stays the same.

[David King]

I've found that if I run more than 7-10 g of tension I get internal shorts between layers. Heavy insulation would probably alleviate this problem but it's a trade off between room on the bobbin vs how many coils I lose along the way. Just because the wire company says recommended tension for 42 AWG is 22-28g that in no way means you need to run that high a tension to get good looking and good sounding coils. If you are wanting to max out production and wind at 3500 rpm and don't really care if half your coils have a defect in them then go right ahead. Otherwise run the minimum tension for the lowest speed you can afford to run at.

[Bruce Johnson]

David, that seems low. I wonder if you have something else causing the shorting problem?

I'm running #41, which is slightly heavier, but it's single build. I wind at 1000-1200 rpm, automatic feed, 25 gm tension, tight layering. I've run as high as 35 gm, but that seemed to squash and distort the coil shape too much. But I've never seen any kind of internal shorting problem. The DCR readings are very consistent. I don't think I've ever had a bad coil with an unexpectedly low DCR.

Maybe you are bending or kinking the wire too sharply somewhere in the path between the spool and the bobbin? Could that be damaging the insulation?

[larams]

Thanks for the explanation guys. I gave it a try this morning. My eyeball gauge was way off. The tension I had been using was in the 30's. Probably why I had a few breaks.

[David King]

Bruce, I've thought about this a lot and I think it stems from using a spool of essex wire that had particularly thin SPN. I bought several of these spools off ebay years ago for less than $5/lb and have been using them up slowly (we're talking over 30 lbs of the stuff). The wire measures out at only .00255"- to .00265 which is pretty thin.