Why Does My Print Go Nuts?

[JamesCRocks]

Hi,

I've been printing fairly successfully for a while but then this happened (apologies, I don't seem able to link to images):



I can also, on these two parts of the print, see where (when) it happened. The layer shift is clear:



From my POV, it's not irreconcilable but if anyone has any idea how to stop this kind of thing happening, I'd appreciate it.

Thanks

James

[CrazyIvan]

The spaghetti monster!

It's a result of the nozzle being in free space rather than printing onto something. The question is... why?

• I don't think it's the case here, but the model could have been sliced without support on overhangs.
• If objects detach from the build plate and shift, subsequent layers will be de-registrated. Looking carefully at your photos, I think this is what has happened. Try using brim rather than skirt.
• A possibility is that, if this is a bed-slinger printer (platform moves in X or Y, while the nozzle moves in Z and Y or X), tall thin objects can wobble and then the nozzle (or something else) catches it and knocks it sideways. Try slowing the print speed down.
• If an X or Y motor skips because the controller is trying to drive it too fast, or there is a defect in the mechanics, it will result in de-registration (after the initial calibration, most FDM printers use dead reckoning rather than feedback control). Try slowing the print speed down.
• If it always happens at exactly the same Z over multiple different prints, look for a physical defect in the printer.
• If it always happens at exactly the same Z but only on that specific print file, look for an error in the model or the slicing. Use the slicer's preview facility to look at what the nozzle is doing around that point. Cura can even load the Gcode file post-slicing and animate the nozzle trajectory.

As for embedding images, see here: https://www.3dprintersforum.co.uk/viewtopic.php?t=197. I've corrected your post for you.