I just assembled my second kit over the weekend and it looks pretty good so I configured marlin with U8glib and loaded it up but the printer gas been doing some weird things. The mega connects and gives eeprom settings but the stepper don’t move, they just twitch. Whenever I hit a limit switch the mega disconnects. I’ve replaced the mega to no avail and believe the problem t be either the ramps 1.4, marlin, or wiring. I’m about to order another board, but could it be any of the other two?
If it’s disconnecting when a limit switch hits, the limit switches are wired incorrectly. You’re probably shorting 5v to ground.
You don’t NEED limit switches technically. Using G92, you can set where the printer thinks it is. Manually set the X/Y to the 0 positions, and do G92 X0 Y0 – that will set those. Then, if your Z isn’t at the bed yet, send a G92 Z100 and move it down until it’s at zero manually. Then set G92 Z0.
This should at least allow you to ignore the endstop problem for the time being.
The motors twitching can also be too high of a speed, microstepping set incorrectly, acceleration too high, etc.
After you have everything set up, do something like a G1 X50 Z10 F300 and see if they move (but slowly) to their intended position.
Sorry I noticed some of this was addressed in answers to my previous question. I replaced the arduino, could I have fried a second one if the switches still disconnect the arduino? The LCD still lights up but I’m not sure if that means it’s okay. The stepper drivers are configured correctly but I have no idea if I fried them.
If it’s a RAMPS board, unplug the arduino and test it separately – upload the blink sketch to it. If that works, it’s likely the arduino is fine. Just because the LCD lights up, that only means your voltage regulator isn’t fried. That doesn’t mean anything for anything else, good or bad.
It could also be insufficient power coming from the stepper drivers. Have you adjusted the trim pots?
Uh oh, limit switch issues. Which style do you have, the correct ones or the Chinese knock-offs that have the switch backwards on the PCB? The arm should come off the switch on the side away from the connector, and point towards it. If it’s opposite, pointing away, then it’ll short 5V to ground when actuated.
All of my switches from Cobblebot were backwards, so when I hit a switch it shorted 5V to ground and turned everything off. I cut the red wire and they work fine. The ones I’ve bought from more useful sources since then are built correctly and have no problem.
It’s a pretty common problem with these limit switches because there are about 8 versions of the design, and then add to that some companies building them incorrectly, those things are just a huge source of issues.
Oddly I didn’t damage my ramps with my backwards endstops. But that’s a good idea for testing outside, especially if a multimeter isn’t available.
Regarding my “did you adjust the trim pots?” comment, I highly recommend watching this video from @Thomas_Sanladerer if you haven’t already:
3D printing guides - How steppers work and how to adjust their drivers
