Need help with localization on kanger head.
Been building nice tmc's lately.
30awg, 8/7 wrap, .070 id, 1.95-1.97 ohms. Winding directly from the spool on a diy handheld mandrel.
No matter how I tension the legs during localization the coil is offset in the bowl. Always the same amount to one side. Seems to reason that it happens because the legs exit the bowl off center.
I always have to push to coil over to center it (post build). Even though I anneal the coil legs (post wind) to make it easier to manouver it seems this proccess is bit counter productive and sometimes distorts my otherwise perfect coil.
Have any of you found a way to compensate for this (pre build)?
Let's talk about the initial localization of the coil within the assembly. The lateral asymmetry of the coil begins from that very first step. But let's roll it back a bit. I speak repeatedly about "direction of rotation at the exit of turn" for the leads". Why?
The short answer: Don't force the coil into position! You introduce an imbalance of tension between the leads...You need tiger claws! Leads arcing in the direction of rotation or exit from the end turns is useful to properly localize the coil in the assembly cup. Without it an imbalance of pressure on one side or the other from the leads pulls or pushes the coil towards the side of the cup (and other heartaches) introducing distortion into the wind itself and possible interruption of adhesion.
Before the grommet and pin set, it's this simple directional difference that imparts the lateral ranging of the coil that you're seeing. Small variations in direction of the leads, though minute, create an imbalance of pressure against the walls of the cup. The cup's resistance in turn results in a pull or push against the coil causing it to migrate off center. If the direction of the leads and pressure they exert against the cup walls is balanced, the coil will rest undistorted and centered. The longer the legs, the greater this distorting effect may be.
Let's go back to the beginning. I've written frequently that the legs should be facing in the direction of rotation as they exit the turn. Revisit that. Leads that terminate straight up-and-down are more prone to upward pressure that induces
high end turn shorts. My preferred method for preparing the leads before and after insertion into the assembly cub is to
tweeze them (on the mandrel, supporting the back of the coil with a finger) with gentle downward pulls between thumb and index so that they end up looking like cat's claws — pointing in the direction the end turn is exiting from the coil. As well though not sideways either; not inward towards the center of the coil, nor outward away from the coil. Once done you cut the leads shorter to about an inch or inch-and-a-quarter to facilitate introduction into the cup. With very slight pressure squeeze the leads together
and insert them through the shortest distance to the 510 exit possible…the slot at the side of the cup.
If the leads are distorted, you may
massage the leads again to restore their direction and balance the coil. But if not, hey, no biggie. It's the nominal center you want but more importantly the orientation. If the coil appears in adhesion you may use a tweezer to gently move the coil to the center before or during pulsing.
The main object of the set is to balance the tension in the leads.
I should emphasize that
the goal is too terminate at the end of the day with a
balance of tension between pos and neg leads at the final
push in of both grommet and pin. Sometimes to accomplish this requires several minute steps. That's the approach, taught and balanced symmetry. You're going to be massaging the leads to maintain the direction and claw until you have them set in the direction of exit at the grommet. Once there slight tension applied to both leads by hand or lightly with a forceps will stabilize the coil towards the center
if the lead tension is balanced.
After the grommet/pin set, if the coil is in an apparent symmetrical orientation — not skewed diagonally (stretched across the mandrel) and no vertical skew up, down and no rotational or horizontal skew (off axis from from slots) — you've done an awesome job in seconds. It doesn't matter if the centering is perfect. You have a keeper.
The claw is your friend.
Good luck.
