Burn test conducted (sans endstops, for which it turns out that the screws called out by the instructions are completely wrong). Results.... mixed.
Smoke: none (aside from puff from the hot end, which appears to have been the PTFE tape cooking in)
Extrduer: turns just fine, and pushed about 1in of filament up the Bowden tube... after which the filament jammed somehow and snapped off at the hobbed bolt when I tried to withdraw it. I'm going to have to completely disassemble the extruder to figure out how it jammed -- there's nothing there for it to jam on! I ran filament through it several times offline without a single issue.
(side note) whoever designed the extruder so that the retaining nuts fall out when you open the idler, and made the holes for those nuts nearly inaccessible due to the motor being in the way, needs a nerf beating. Ditto for the the way the main gear blocks access to the motor mounting screws. First improvement once parts are printable: modified extruder).
Addendum: somehow, the filament appears to have jammed at the brass exit fitting of the extruder. After an inch of filament was already through it. Still no possible explanation, but clearing this is going to be nearly impossible without wrecking a critical part.
The X and Y axes will move nicely (albeit only in + direction right now, due to not having any endstops). The Z axis... I dunno. One motor jumps and turns erratically, the other doesn't even hum. Which is nuts, b/c those two motors are wired in series.
Hot end: heats up fast. Thermistor says 200C, my IR thermometer says ~50C. My finger says "ow!". Going to have to look into that.
Finding a schematic for the heated bed is now a necessity. As far as I can tell chasing signals with my meter, it looks like the instructions got the control/sensor wires for the bed all swapped around. But given how easy it would be to burn out something, I don't dare just start swapping wires until I know exactly what I'm dealing with.
Also, there seems to be something wrong with the instructions for the "current limiting" instructions for the stepper drivers. The Melzi instructions are using the same A4988 drivers as the Sanguinololu does, and explicitly calls out the reference voltage as 0.4V. But the Sanguino instructions reference a page from Pololu that doesn't give a reference voltage, but states that the reference resistors are 0.05ohm. Which, for the 1Amp limit of the steppers, would seem to indicate that the ref voltage should be 0.05 to 0.07V, which is close to impossible to set -- the trim pots move more than that if you breathe on them too hard.
Smoke: none (aside from puff from the hot end, which appears to have been the PTFE tape cooking in)
Extrduer: turns just fine, and pushed about 1in of filament up the Bowden tube... after which the filament jammed somehow and snapped off at the hobbed bolt when I tried to withdraw it. I'm going to have to completely disassemble the extruder to figure out how it jammed -- there's nothing there for it to jam on! I ran filament through it several times offline without a single issue.
(side note) whoever designed the extruder so that the retaining nuts fall out when you open the idler, and made the holes for those nuts nearly inaccessible due to the motor being in the way, needs a nerf beating. Ditto for the the way the main gear blocks access to the motor mounting screws. First improvement once parts are printable: modified extruder).
Addendum: somehow, the filament appears to have jammed at the brass exit fitting of the extruder. After an inch of filament was already through it. Still no possible explanation, but clearing this is going to be nearly impossible without wrecking a critical part.
The X and Y axes will move nicely (albeit only in + direction right now, due to not having any endstops). The Z axis... I dunno. One motor jumps and turns erratically, the other doesn't even hum. Which is nuts, b/c those two motors are wired in series.
Hot end: heats up fast. Thermistor says 200C, my IR thermometer says ~50C. My finger says "ow!". Going to have to look into that.
Finding a schematic for the heated bed is now a necessity. As far as I can tell chasing signals with my meter, it looks like the instructions got the control/sensor wires for the bed all swapped around. But given how easy it would be to burn out something, I don't dare just start swapping wires until I know exactly what I'm dealing with.
Also, there seems to be something wrong with the instructions for the "current limiting" instructions for the stepper drivers. The Melzi instructions are using the same A4988 drivers as the Sanguinololu does, and explicitly calls out the reference voltage as 0.4V. But the Sanguino instructions reference a page from Pololu that doesn't give a reference voltage, but states that the reference resistors are 0.05ohm. Which, for the 1Amp limit of the steppers, would seem to indicate that the ref voltage should be 0.05 to 0.07V, which is close to impossible to set -- the trim pots move more than that if you breathe on them too hard.