Post by antigua on May 17, 2017 0:14:03 GMT -5
I tried winding a few pickups (hand guided, no CNC machine or the like), all 8,000 winds of 42 AWG, hoping to observe something about the the relationship between coil tension and capacitance. I tried winding some tight and some loose. What I found instead was a huge amount of variation, and though I'm not sure what variables contributed to the differing results, it seemed that wind tension alone certainly didn't guarantee an outcome.
The table below shows coil thickness (which are rounded off to some extent, because the un-wax potted coils coils are fairly slack compared to more firm, wax potted coils), and electrical measurements.
8,000 turns, 42 AWG, Strat type pickup
| Coil Width (in.) | Cap. (pF) | Inductance (H) | Res. Peak (kHz) | DC Resistance (kOhms) |
| 0.54 | 161 | 2.418 | 7.72 | 6.20 |
| 0.6 | 167 | 2.458 | 7.63 | 6.17 |
| 0.6 | 135 | 2.491 | 8.36 | 6.02 |
| 0.6 | 152 | 2.402 | 8.08 | 6.21 |
| 0.6 | 84 | 2.365 | 8.36 | 5.96 |
| 0.63 | 115 | 2.311 | 9.37 | 6.02 |
| 0.66 | 148 | 2.564 | 7.9 | 6.18 |
| 0.7 | 102 | 2.578 | 9.37 | 6.15 |
| 0.6 | 84 | 2.365 | 8.36 | 5.96 |
| 1.54 | 63 | 2.876 | 11.0 | 6.47 |
The results are so random that the take away isn't any kind of correlation between wind tension and electrical values, rather it's that in order to get usable data, the winding process would have to be really controlled, or some special attention would have to be paid to a perfectly duplicated process.
Another take away is that 8,000 turns around a fixed bobbin can result in a wide array of L and C values, depending on variables of the winding process. The loosest coil I wound did have the lowest capacitance (#6 in the picture) while the tight ones had the highest, but there were also counter examples on extremes, where coils measuring 0.6" widths had capacitances as low has 84pF and as high as 167pF. The inductances were also highly varied, and the DC resistance varied by as much as as 500 ohms. It's a total mess of values, and I really don't know what all accounts for it.
The other strange thing is that sometimes I wound with a higher tension, but never the less, the coil would come out about as thick as a coil wound with a lower tension. It was difficult to get a coil much thinner that 0.60" inches without dragging on the wire so tightly that it risked snapping. I did manage to get one down to 0.54", by surprise. Fender's machine wound single coils routinely come in around 0.50", I'd like to see how they achieve those tight winds. I'll watch some YouTube videos and look carefully at whats going with their rigs to see if I can figure out how the do it in the factories.
I'm going to have to take another stab at this, rip all the wire off the pickups I wound so far, and try again once I can find a way to improve the winding process. Consistency comes with practice, I suppose.
As far as consistency goes for major manufacturers, I haven't been able to measure that too well, due to the fact that I often only have one set of a given pickup model, but there are several from Fender in particular, where all three pickups are the same coil specification, such as the Fender Pure Vintage 56, 59, 65 and CS 69, and it appears that there is about a 30pF spread in capacitance with their pickups.
In summary, this is more of a progress update than anything else, nothing too interesting to report yet.
Some observations about winding the coils;
- it was very difficult to get a "in between" wind tension. I tried moving the clamp around, and I could feel the resistance change when I pulled on the wire, but once I went to wind the coil, it had a tendency to either wind rather tight (0.6"), or else it would be extremely loose (like #6 in the picture above). I tried to make a pickup between #6 and the others, but it was seemingly impossible.
- as far as scatter goes, if you have the winder running at a high RPM, the wire tends to move around a lot on it's own. With lower RPM's, if you don't deliberately move the wire, the wind will focus sharply in one place. Regardless of the RPM, if you don't intentionally balance the coil out, or be rhythmic with your hand movement, it will clump up to one side or another.
- for the tensioning, I did what I've see some others had on the 'net; clamp the wire between hard backed felt or other fabric. It seemed to work fine, if you clamp it right over the wire, the pull is very tough, and risks breaking, so you just clamp it a little off center to give it slack. The only draw back is that it might be hard to repeat the same tension again with such an ad hoc setup.