I was printing a netfabbed stl. Everything looked fine. I left the room for a few hours to come back to this. It must have failed just after I walked away. The printer is only 3 months old.
never seen this happen before…
Just contact lulzbot they will most definitely take care of this…
Out of pure curiosity, what specific model were you attempting to print???
It looks like the head started moving DOWN during the print, and it bound up on the model and ripped your head apart. That, my friend, is what I call a catastrophic failure. 
Pretty sure you lost your Z axis motors there for some reason but X and Y and E were still functional. which is weird because it can’t be a fuse in that case then. At any rate, now you know why you don’t leave your printer unattended eh?
I was printing a hollow cylinder with one end closed off by a rough diagonal plane. This stl file was checked with Netfabb. Unfortunately I can not upload the gcode (file is too large but it can be downloaded from here) but i have attached the stl of the model we were trying to print.
As far as I can tell from the print it seems to have decided to ignore the commands to increase the z height after the first ~2cm of the model. The g-code itself seems fine as far as i can tell (i have checked it in a gcode viewer, and manually looked to check that z is increased at each new layer).
We are currently waiting to speak to Lulzbot Support (they are not open at the moment). Looking closer at the broken extruder mount, it snapped in line with the hotend bolts.
Where as I agree that you should sit with the printer at all times, this isn’t always practical. This print was supposed to take 12 hours. I’d sat with the printer for the first two hours and it was fine. It’s just unlucky that it seems to have failed right after I left the room. However I would hope that a failed print wouldn’t destroy the printer itself.
Has anyone else had a related issue where the printer just stops increasing in z?
Cylinder.stl (1.6 MB)
The heat sink on the Z driver may have fallen off, which I read happened to a Mini owner a week or two ago. That would cause the chip to over heat from the load on it and start dropping steps. AKA - drag the head on the print and snap the carriage.
Thanks for the head’s up. It looks like that is exactly what has happened. We didn’t have a heatsink on Z, we had one stuck to the LCD SPI connector beneath the controller chip.
We’ve spoken to Lulzbot tech. support and as expected, they were very helpful. In order to get back up and running as soon as possible, we are purchasing a new Taz 5 and shipping our broken printer back for a refund.
The first thing we’ll do with the new one is check the heatsink is in place!
The heat sink fell off the Z stepper driver of my Mini. Result was missed Z steps and a messed up print, but fortunately no machine damage.
I just don’t think the adhesive pads on those heat sinks are up to the task, given the vertical orientation of the board. They work fine for VRAM on video boards, but video boards don’t shake/vibrate like a 3d printer doing fast infill.
So I cleaned off the adhesive and used Arctic Silver Alumina thermal epoxy to remount it. I also added sinks to the X and Y chips while I was there. Probably not needed, as I think Z gets much hotter due to driving two steppers.
I purchased a TAZ 5 in December 2015 and ran into the same Z axis issue during a print. At one point, turning the printer off and then back on, there was a loud pop and spark from the controller box. A quick look uncovered a dislodged Z driver heat sink that caused a short. Lulzbot support was great and they sent me a replacement printer. I wonder how prevalent this issue is?
