So I fired up the RAMPS 1.4 test software quickly, before work, this morning, and almost everything seems OK. The arms wiggled smoothly, as well as the extruder gear, but the z-axis was only moving one way. I could hear the stepper straining to lift the bed, and with a slight amount of manual support from below, it lifts. Not a big deal, I am working on the assumption that the current to the motor is limited at a too-low level. The StepSticks have an adjustment pot, I will tweak that tonight.
I then uploaded the Morgan Marlin code to the Mega, and fired up Pronterface. I set the hot end to heat to 185 degrees and the bed to 60 degrees (default PLA settings). The hot end controls beautifully, the heated bed not. No LED, no power on the wires. The hot end draws about 4 A.
Almost alarmed, I then remembered that the default setting for heated bed thermistor in Configuration.h is "0", meaning no thermistor present. I changed that to "1" in the Arduino IDE, recompiled and uploaded, and started Pronterface again. Success!
The heated bed draws about 8 A from my power supply, and temperature is reached fairly quickly. I'm using a Nissei 25A switch-mode power supply (from my amateur radio), which has a voltage adjustment (approximately 9 to 16 Volts) and both voltage and current meters on the faceplate (see photo in previous post).
The thermistor (little glass bead one from ebay) is mounted by spread-eagling the (very thin) legs and Kapton-taping it to the bed PCB from below (glass bead protruding through the hole in the centre of the board). The tracks are oriented UP in my build, with the glass sheet right on top of that. The thermistor stands slightly proud, so the glass pushes it down against the Kapton tape, so it touches the (underside of the) glass well.
This means the motors, heating elements, and thermistors are all connected properly. The end-stops will be tested next (tonight).
Unfortunately, I also have a proper day-job, which means I can only play again tonight.
No comments:
Post a Comment