Spontanous heatbed desoldering: final solution
Interesting. Better make sure you prevent it from flexing the traces you peeled up or its going to tear itself apart.
Looks very scary to me.
If the temperature is enough to desolder the leads, that insulation on the wires is toast. You need to #1: make sure to use wire that is rated for the current you’re sending through the heater. Usually such wire has a nice thick layer of high temperature tolerant insulation. The thickness is important: it ensures that the wire can’t get folded back on itself to the point that it can’t safely dissipate the heat of the current it carries. Number 2: I’d be a bit concerned about heat cycling leading to loosening of the ad hoc screw terminal you’ve built. Suggest putting something with a bit more thermal mass (bigger chunk of metal) where the wire connects, to reduce the range of the temperature swings. Better than that, you might try finding a terminal that is actually rated for the current you’re sending through it at the bed operating temperatures.
My thoughts exactly!
This is a fire waiting to happen!
Well this wires is teflon coated, after few days of printing I can’t see any signs of insulation damage. I planing to get some lead free solder later, which have higher melting point, and try it someday. As for fire, IMHO then wire suddenly came of from it’s place, and can short-circuit to the chassis or another wire, is more dangerous and possible event. Use on your own risk, though.
The solder probably isn’t being undone, it’s probably being broken by fracturing. This kind of heater is known to have solder breaks. You need a strain relief to hold the wire so the joint isn’t flexed, especially if it’s a moving bed.
The bed heater should be replaced.
I’m pretty sure it was desoldering, since I soldered it back 10 times before decided to use screws =)
I’m pretty sure you’re going to have a fire if you don’t use heavier gauge wire.
Desoldering can happen even if most of the wire doesn’t reach high temperature if the resistance of the joint is too high. @Jeff_DeMaagd is right about the need for strain relief. Flexing the joint might have been intermittently reducing the wire-to-metal connection and made the current go through the solder instead, which has a higher resistance.
it’s really hard to solder to those heating elements. I had the best luck with silver solder and a tiny bit of acid flux from a stained glass kit. Clean it well after soldering. I use very fine multi-stranded wire with a high temperature silicone insulation, it’s very soft and floppy and good for 20Amps. It’s sold at hobby shops as the RC battery leads for electric cars and airplanes. I then tape down about 2" of wire to the heater with kapton tape to act as a strain relief for the solder joint.