V2 thermistor

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carter
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V2 thermistor

Post by carter »

Has anyone figured out a durable way to attach the (original) hot end thermistor that doesn't create a stress point that breaks the wire?

My original solder lasted 22 hours (this seems very small... I suspect my odometer got reset) or 1 year, but after pulling it out of storage it only lasted a couple prints before breaking. I'm on my 4th attempt at soldering that tiny wire flapping around behind the heater wires and I keep getting cold joints that last a couple prints.

Given the tiny wires on the thermistor, this seems like an unavoidable repair. I admittedly chose a connector with wires that are much too large, but I don't think it matters how well you secure the wires - there's a lot of energy jiggling this thing and it's all going to end up fatiguing the solder joint of that tiny wire!

My first plan is to print a little post to screw in next to the notch where you zip tie the wires so I can add more zip ties so the whip doesn't cause as much stress.

I'm also wondering if there is a way to secure the tiny wire next to the hot end.
a) place splint (that can take the heat) along wires/solder joint? I worry this may shift the stress and cause the thermistor end the break... then I'm doing a much more extensive repair.
b) use some sort of heat immune, thermally neutral, magic epoxy to encase the entire wire? I have no idea what epoxy though.
c) Is this hopeless? Is a major overhaul is inevitable? there's a youtuber (DooDad) who tapped the thermistor hole and bought a threaded one, eliminating the need for thermal glue. Worst case, even if this also breaks, it sounds much easier to repair. BUT this is a time consuming project with a non-zero dollar cost; when I have more money I'll just do the full V3.2 upgrade... so in the short term, are there thermistors with thicker wiring that I could expect to last several hundred hours?
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Re: V2 thermistor

Post by geneb »

It's been *YEARS* since I needed to wire up a thermistor to the old hot end, but memory tells me that you use uninsulated crimp ferrules to attach the signal wires to the Thermistor leads, you don't solder them. The Thermistor wires should have tiny PTFE tubes covering them.

I'm pretty sure the YT video I did on building a hot end is still up - my channel is https://www.youtube.com/f15sim - rummage around in there, I'm sure you'll find it.

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