So, I haven't really needed to ask for help re:

So, I haven’t really needed to ask for help re: 3d printers in a long time, but I have been ramming my head against a wall for the last couple of days and this time I might need some help.

The X axis on a makergear prusa at my hackerspace seems to be exhibiting some “backlash” on the X axis. Except, I’ve tested nearly every form of backlash I can find. I redid the X belting, checked the pulley, idler, they’re all tensioned correctly. Afterwards, I figured it might be the driver overheating and going into fault mode, but it keeps happening the exact same place every time. Nevertheless I replaced the driver, added a big ol heatsink on it, and same thing happens.

I went back to the belt, quadruple checked it, even checked the carriage and its attachment, I can not find any form of mechanical backlash at all on this machine.

This on a ramps 1.3, mega 2560. Can stepper motors “go bad”? It seems the only thing I haven’t attempted yet is replacing the stepper motor. Any suggestions?

can you swap the x with the y motor to see if it’s the motor that way?

@Nathan_O_Kane thanks for the idea. Motor seems to be the last resort at this point.

I have had a long hatred of the MG Prusa that I bought. I had to reprint both motor and idler ends on my Mosaic for the x axis and switch over to GT2 belts to get the backlash problems fixed. Something goofy about those ends. And the spacing is off on the z axis smooth rods and leadscrews so you have to stick with the MG designs. Try swapping motors and look for any nicks in the smooth rods but after that try printing some new parts and see what happens.

@Brian_Evans this isn’t a new build. This machine has been running nearly non-stop successfully for over a year. This isn’t a case of the rods being off or anything like that, I can assure you. Nothing visible, externally, is damaged in any way shape or form, and sans belt, the X carriage slides beautifully.

However, this machine has been left in a very humid area for a very long time. No corrosion that I can see externally, because the whole machine is stainless, even the threaded rods/nuts/etc

I had issues like this. Turns out, my belts had stretched in one spot, and every time that spot went over the pulley it caused dimensional issues in the prints that looked very much like lash.

Try turning the belt around the other way so that the section that currently goes over the idler is going over the motor pulley. If that fixes it, replace the belt.

@ThantiK Hey youre the one asking for help. Where did I talk about a new build and why does that matter? Shit breaks and you have a few suggestions here for things to try.

Are you still using those awful original XL belts and pulleys? I cringe every time I see someone useing T5/XL belts, especially with manufactured pulleys. The only reason that belt profile was ever acceptable was because it was difficult to print pulleys for a better one (partially because of the inaccuracy caused by by those belts). I would recommend replacing the belts even if it was working properly…

@ThantiK can you provide a picture of what exactly your fault looks like?

Yes, motors can go bad, but steppers (being brushless motors) are generally very robust. Apart from physically breaking in half, they can fail by:

  • Reaching the curie temperature of the magnets (usually above the glass temp of ABS)
  • Burning out a winding. Again, would require the motor to receive way too much current. If one of the coil is mechanically damaged, thermal expansion of the windings could cause funky behavior.
  • Bearing wear. Those little bearing in our steppers are not made for the axial loads we’re putting on them by tensioning the belt. so they might fail prematurely. This should be easily noticeable.

What i’ve also seen is the rotor rubbing against the housing due to a sloppy assembly.