Extruder Zig-Zaging off print zone mid print

[ShouT32]

I recently purchased and assembled a ANET A8 Prusa i3 3D printer. When doing a print everything goes fine and well for the first few minutes, then all of a sudden the extruder starts zig-zagging off the print zone and continues to try and print off the print bed.

Any suggestions on how to fix this?

[3DFlip]

Have you checked if the file is not corrupt? Sometimes my Anet does like this, and if I fix the file then all works fine

[DazDavid]

Sounds to me like a loose belt that looses grip at some Point. Try to tight them again and print a bit slower.

[ShouT32]

I got a reply from a user on Reddit that seems to be the exact problem i’m having, he suggested I check when the y endstop is being hit and sure enough the y endstop was getting a false positive of being triggered which the bed then proceeds to be pushed forward because it thinks it is at the end. He said he only way he solved this was to unfortunately replace the board

[DazDavid]

Hm, somehow makes sense. But also the Microswitch could be the problem and trigger throught vibration or something. You could replace the switch first and see if that solves your problem.

[ShouT32]

I switched the x and y switches because then theoretically the exact same should happen just on the x axis but it didn’t, the exact same thing was happening along the y axis

[DazDavid]

Strange. Did you try to print another file? If yes then probably is the mainboard the guilty one…

[ShouT32]

I switched the x and y switches because then theoretically the exact same should happen just on the x axis but it didn’t, the exact same thing was happening along the y axis

[ShouT32]

Yes i tried multiple files. The original gcode files that came with the printer, one sliced with cura and then one from repetier host. All the same result unfortunately

[loopingk8]

Hi, please share your printer settings like speeds and acceleration(if changed). Does the printer make any unexpected noises like craking or skipping noises? Are the Y and X belts tightened? Check the motor grub screws (check if they are tight) and check if the idler pullys are freely moving.

[travisW]

It seems like your X and Y belts are too loose. This causes them to skip gear teeth sometimes, making your printer start printing at an X/Y offset from where it was before.

To test if this is the case, print slower (fast print speeds increase the belt jerk, which increases the chance your belt will skip teeth). If your print turns out OK, then this is your problem.

If this is your problem, then either cut your belt shorter or print some belt tensioners (slowly) to tighten your belts. Search thingiverse for “anet tensioner” to find X and Y tensioners.

[travisW]

Another option if this is your problem would be to move the endstop to the opposite side and change your firmware to reflect Y_MAX_ENDSTOP instead of Y_MIN.

I have NO idea if this would work, I just thought of it and figured I’d share.