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Power resistor teardown

Im in the middle of preparing to my next big announcement ( Hot-end v3.0), so Im organizing photos on my computer, etc...
So just found this:

When you build more then 20 hot-end, you will break sooner or later a resistor anyway.

I had a choice to sacrifice the heater block or the resistor.
So I choosed the resistor, and I salvaged the heater block:-)

But if you have only a few, or maybe only one, that it is nice to know how much care is needed when you handle them.

Maybe some of you are interested what is inside in this power resistor and how it was made.

At both end there is closing caps, where the internal heater strip/wire and the outer connection mets:

At the middle there is a ceramic cylinder, where the heater strips is wounded around:

Between the two caps, there are some outer ceramic coating,
so the round wire resistor will never be perfectly round,
because at the two ends, the caps are always wider diameter then in the middle.

In reality there is a 0.1-0.15mm deviation in diameters.

Also you can easily pull off the caps (griping the wire with a pliers), and destroying the resistor.
Also the heater strip/wire is only coated with one or two layer of insulating paint, so if you force
the resistor it will likely crack exposing the heater wire to the outer world looking for possible
short circuit;-).

So my advice is:
If your resistor goes into the hole with a gently force, then fine, but never push hard into.
Dont pull, push twist the resistor with a plier.
If you cant push the resistor by hand into the hole, then drill out the hole with 0.1mm wider
drill bit and wrap the resistor into aluminium foil, then push it into.

Observe how thin is the coating around the heater wire:

Hope this article was useful for some of you.

Stay tuned to my next announcement!;-)

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  1. The coating is not just paint, it’s a hard silica glaze. it can take lots of heat but is brittle

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