D
Deleted member 58360
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If you preheat and don't check the clamp(s) then it can go slightly loose. Not enough to fail immediately, but enough that it can cause problems.
The wire tries to expand when it heats up, but it can't - but it will still contract a bit when it cools (old trick to remove a stuck bearing is to weld around the race to heat it up a lot while only heating the surround a little, then when it cools they drop out).
You don't get the same effect in use because it doesn't get nearly as hot as when preheated bare.
That little bit of contracting might be enough to throw a fault...
Stuff like kanthal develops an insulative coating of it's own as it's heated and cooled, which could be getting in there and being broken (and making contact again) when you wiggle it.
Next build, do as normal but just before you'd normally wick wobble the coil about a bit and watch the ohm reading to see if it wavers.
As before, this is just a guess, but another guess with a sensible reason behind it
The wire tries to expand when it heats up, but it can't - but it will still contract a bit when it cools (old trick to remove a stuck bearing is to weld around the race to heat it up a lot while only heating the surround a little, then when it cools they drop out).
You don't get the same effect in use because it doesn't get nearly as hot as when preheated bare.
That little bit of contracting might be enough to throw a fault...
Stuff like kanthal develops an insulative coating of it's own as it's heated and cooled, which could be getting in there and being broken (and making contact again) when you wiggle it.
Next build, do as normal but just before you'd normally wick wobble the coil about a bit and watch the ohm reading to see if it wavers.
As before, this is just a guess, but another guess with a sensible reason behind it
