Thank you very much for confirming that chet. It's really quite common to see coils go erratically hot when being pulsed into life. And for bad flavor to result if the process of creating them by pulsing isn't completed (whether pre torched, compressed or not).
Please listen up all you dedicated tension winders…these are important tips.
Microcoils whether tensioned or compressed may exhibit hot turns or leads when initially fired anywhere that there is a deviation in symmetry. These deviations are caused by stresses introduced into the coil (pulling apart) through handling, tensioning, etc. that alter the original shape of the coil as wound. Or they could be the result of graduations in the tension applied while winding. You will see consequently variations in resistance typically to the low side...
until oxidation begins and possibly beyond until completed. This is typical. We all vary in consistency. If deviations are numerous and spacing abundant between turns, as with torched and compressed coils, this may take quite a while. If they are severe, you may never achieve adequate alumina oxide fusion of the turns and the wind will remain unstable and squirrel-ly in behavior.
The more exact the symmetry, the more uniformly consistent the alumina oxidation of a coil and the more durably, reliably, that the coil will perform.
I strongly recommend you consider tension winding your coils in 30 seconds or less. I experience a ratio of better than 55% first fire microcoils (exhibiting
the effect) with tension winding. That means less handling risk to the symmetry that you may experience, less firing losses and rewinds, the more consistent
you become in winding them in those 30 seconds. The more you do, the more they're good. A great formula for success.
I'd say the performance of a uniform tension wound coil is nothing less than spectacular compared to a conventional coil of any kind. So much so that I reject most anything that doesn't fire full micro in a couple'a three pops. It's just not worth it. And seldom does a formed (torched and compressed) micro ever do that. You almost always have to cure inconsistencies that could have been averted by a simple wind.
You may need to pulse a t.mc. 2 or 3 times even if the tension applied is relatively consistent end to end. That's not unusual. We're none of us perfect. You may see reversals of the coil heating end-to-end as you do so (and squeeze or compress the coil). These are indications that stress was introduced into the wind as you set it in the head. It's essential you terminate it on the mandrel you used to wind it to avoid these stresses. Induced stresses will extend the amount and intensity of pulses required to fuse the coil and perhaps degrade it with firing. Another reason that focus on tensioning consistently builds a better coil. You may be able to complete a coil successfully despite this if the tension was fairly even.
Additional stresses, frequently varying tension such as mismatches of tension between the leads, can be relieved at times by
raking the top of the coil before and as you pulse it. My
kudos to super_X_drifter here, who conceived the microcoil, for this very practical observation.
Raking cures misalignment of the original symmetry. It causes the coil to snap out of position and then snap back (hopefully) into the shape it was wound. It may take a few tries. THEN…you will see the coil resume it's actual wound wire length resistance. Proceed confidently to complete oxidation. You've got a winner!
These are tips that hopefully may get you through the first few fires quickly rather than be tempted to burn the coil to death pulsing and squeezing. I very seldom do much compression these days and if so very lightly using a ceramic tweezers. It seems the very act of compression particularly as the coil is hot and malleable affords yet another opportunity to skew and mangle the coil. So much of the hardware and mechanics we have learned and grown accustomed to are largely unnecessary, or redundant. We just have to wind a good coil.
So me, I wind another when they misbehave. It takes seconds. And time is precious friends.
I hope this helps…and please, wind that tensioned, and good.
Good luck.
