Well darn, got a bad soldered heatbed off Amazon :o(
Wondering if it’s even safe to use?
Bought from Amazon seller ‘TriGorilla’ who I cannot recommend. Look at that solder, it’s like a child was being taught to solder, then they sent the thing to me. Either that or it was a home soldered ‘kit’ unit that was returned, then sent to me. Maybe both, home soldered by 12 year old, then returned to Amazon, then sent to me? I dunno but it looks so bad I am wary of using this thing. Is this even safe?
Return? Resolder? Use it? I don’t have a desolder pump and don’t want to buy a tool that costs as much as the darn heatbed just to fix it. Any other no cost method?
Also look at those wire ends, that is how it arrived. So disappointed.
As “ugly” as it looks, the edges of the solder mass have flowed into the solder pads on the heated bed. There are no visual indications from the photograph of a cold soldered connection, and I’ve made my share of those oatmeal-looking masses of solder.
You would not have to desolder the connection in order to add solder, but you risk the chance of having movement imparted by your actions by so doing.
Your mission, should you accept it, would be to firmly secure the wires with tape or similar substance to prevent movement while you apply heat and re-apply solder.
You would want to have some form of semi-permanent strain relief for any connection of this sort, to prevent fatigue breakage at the wire/solder interface. I suspect hot glue would melt, if the underside of the heat pad gets hot enough. Perhaps a high temperature RTV silicone to provide such protection.
Have you got iron and some solder though? Just as your own solder to clean up the joins, it’s not like there’s an elephant poo of solder there, just not enough. Definitely cut the other ends, strip them, twizzle them and tin them
thanks guys. so the resistors on the heatbed cannot be damaged by extended attempts at soldering with a cold iron or whatever happened here? I am worried about the resistors on the heatbed with ‘bad’ soldering. if there is no issue then I would just resolder the joints better and move on I suppose. Do those resistors get hurt from bad soldering in close proximity? there are little beads of solder all over them and around them, tiny little blobs from whatever the heck was done to the main contacts.
You can damage both the resistor and the two LEDs on the bed, but it should not affect the operation of the bed. Close proximity to the resistor and LED would mean direct contact. The existing spacing will shed any heat sufficiently to not damage the SMD components (surface mound devices) unless you bop them with the soldering iron. I destroyed a cheap chinese laser pointer module resistor by crushing it with pliers, but that sort of ham-fisted result is to be expected, although not desired.
Slap some red high temp RTV from the auto parts store on there for strain relief like @Fred_U mentioned, run it for 3 or 4 years until it fails, and then worry about it (or buy another). No really, the joints aren’t pretty, but like Fred said the joints are wetted and will most like be fine for years. Strain relief is a must - even a good looking solder joint will fail without proper strain relief. My quadcopter fell out of the sky last week because a factory solder joint without strain relief failed from the wire vibrating.
Thanks all of you, its a Delta heatbed so strain relief is not a huge issue, I will provide some though for the occasional repositioning. Bummer about the quadcopter! hope it wasn’t damaged too badly!
@Mr_Bonce You’re not supposed to tin the ends of stranded wires carrying this kind of current through screw terminals. You want the bunch of strands to flatten as the terminal is tightened so it makes good contact across lots of strands. If you tin the tips, the screw terminal will tighten down on a much smaller contact area. That causes resistive heating, which causes the tinning to creep, which decreases contact pressure and contact area, which leads to more heating, and solder oxidation, and eventually you get a runaway overheating connector failure that can cause a fire.
Tinning heatbed wiring works ok for a while, but has a high probability of eventually burning something up. Don’t do it. It’s unsafe.
@Ryan_Carlyle The best implementation I’ve seen for screw terminals is hobby-store small diameter tubing, cut to convenient short lengths, slid over the ends and crimped securely at the “upstream” end, then flattened at the screw terminal end. A couple bucks of the brass or copper tubing makes a couple dozen connections that are as secure as can be. Proper crimping tools give the best results, of course, but careful use with precision pliers work well too.
@Ryan_Carlyle
Even the ones that would not have a flat interior contact surface would accept small diameter tubing, yes? To prevent damage, the wiring strands would extend to the end of the tubing and be crimped/crushed by the screw, further distributing the forces involved, reducing the possibility of a connection destroyed by soldering. Of course, this also requires an opening sized to accept such small diameter tubing.
thanks again. I figured not to tin the ends for my needs, having a terminal to connect to. i was planning on using ferrules, might do copper tube crimped flat as my terminals have a flat contact area. Might just do well trimmed exposed wire if that seems like its has the best contact, all wires will get a separate strain relief on both ends. A printed bracket with clamp down screws, that is installed with screws into printer frame on one end and controller enclosure on the other. different bracket and cable path for steppers than sensors. Any issues with heater wiring and sensor wiring? just checking, don’t remember reading anything about it like was mentioned for endstops and EMI.
@Fred_U But why add the tubing? The kinds of clamping terminals typically used by 3d printer control boards are DESIGNED for plain stripped stranded wire. If you want to do repeated makes/breaks or get regulatory certification, you’re going to want a properly crimped wire ferrule, not a jury-rigged hobbyist kludge. I just don’t see a scenario where the tubing idea is preferable over the other options.
