Yeah, so… The Monoprice Select Mini I raved about is still a good first printer. I’m paraphrasing a HaD writer here, but it is the model-T of 3d printers.
Even with a failed heater circuit (dead short through the FET, scary!)… it’s a good machine. In the span of a few evenings, I’ve set up a RAMPS configuration under it.
I’m not sure if some of the steppers in my machine might’ve been oriented backwards (or I missed a step?) Either way, I’ve fidgeted and futzed with this machine until I have it almost ready to print useless desktop baubles again.
I say almost ready, because you might notice in the first picture that there is no bowden tube yet. Additionally, there are no nuts holding the hot-end to the X carriage yet… it’s just slipped onto the bolts. But, I can walk each axis, preheat bed and hot-end, and feed it gcode from an SD card.
Then I tried a dry run. I know I have no bowden tube, and the hot end might fall off. I safety-wired the hot-end assembly to prevent that second problem, and ran without filament to make sure the machine followed gcode in what seemed like a sane manner. It did! SUCCESS!
Then, it rebooted about 2% of the way into the print. Poly-fuses. Also known as self-resetting breakers. These little yellow bastards trip at about 15 Amps… sometimes a bit lower. I have a fan blowing across the whole board, and the steppers are turned down to about 425mV while I fine-tune stuff. Nothing jitters too badly, but the damn poly fuses trip after a while.
problem… right there.
The plan now, aside from a new bowden tube and some small hardware, is to replace these stupid poly-fuses with proper automotive blade fuse holders and 20A fuses. I say 20A, because my PSU provides 16.5 or so, and if the printer tries to draw 15A periodically, I’m fine with that. The stupid little poly fuses apparently aren’t, though.