Lost a 14 hour print due to a shift mid way

Did an overnight print last night that failed because about halfway through the print it's like the entire print shifted in one direction. It looks like it happened exactly halfway through and only in one axis. Not sure if this was a slicer problem or what. I don't have a picture as I'm about to run out the door but it basically looked like this. https://all3dp.com/app/uploads/2016/09/3D_Print_Problems_ShiftingLayers-1024x576.jpg

So I'm printing this for a second go and so far what I'm noticing is that there is zero z hop between areas that are being printed. What this is resulting in is the nozzle is getting rammed into things and it's actually breaking some pieces off of the raft. These pieces are then obviously getting messed up. I don't think this was the reason for the shift I saw before because that was uniform across all parts but it could be. Just ONE MORE REASON we need gcode support so we can have finer control over how things are printed.

I have reported the issue with the print head rubbing against just printed areas to Cetus, and I previously opened a tread on this forum about it.

I have found though, that on my printer, screws are shaking loose over time. This leads to the Z gantry getting more and more wobbly.

This combined, with the quick movements of the print head, I think is contributing to the print head hitting the already printed parts.

I would definetly be nice with a Z hop, but check your machine for any sign of loosening connections.

On mine, the screws in the corner bracket behind the control board are completely loose, and rattles around in the bracket.

I've also noticed that the print head over-accelerates on a jump every-so-often, identified by a loud 'clunk' sound, causing the head to lose horizontal registration

I've just had this happen to me just at the end of a 7 hour print - extremely annoying.  Printing PLA with a 0.4 nozzle, 0.25 layers and fast-print enabled.

I've just about managed to rescue the print by turning the machine off and on to simulate a power-cut (make sure head is supported when doing this), allowing the machine to re-initialise and then complete the job.

Bit of a scar on the part though (something for my daughter's birthday).

Not sure where that idiotic smiley came from...