Solved Z Axis issues

I have an R1 with a e3dv6 hotend (still using the wades extruder etc, largely stock outside of that)

I have had nightmares trying to get this guy to print ABS largely due the rather inconsistent performance of the heated bed. I gave up and have switched to PET-g which is beautiful to print with by comparison to either PLA or ABS, but in the meantime suddenly I am having this bizarre issue where, seemingly at random, the printer just utterly fails to elevate the z axis for anywhere between 1 and 6 layers causing the print to crash majestically with a pile of garbage wrapped around the print head.

It's worth noting if I catch it (I can spot it by seeing the layer pushing out past the previous layers, and dull drag marks on the existing plastic, since fresh PET is shiny and oily looking) I can then jog the print up using manual controls and salvage the print. At least until it fails again. It doesn't seem to happen at a regular layer level and sometimes doesn't happen at all (for instance I can usually knock out a test cube without issues) but sometimes it will fail 6 or 7 layers in, sometimes 20, sometimes multiple times on a 20mm high object.

I checked the rods, (both threaded and smooth) lubed with tri-flow (teflon based lube), measured the z axis movements when in standby using the jog controls using a caliper but none of it seems to be the case. I updated firmware, rolled back, tweaked it here and there, but neither physical tuning nor software seems to resolve the issue. And since it's intermittent its a freaking NIGHTMARE to diagnose.

The only thing left I have to really try tweaking that I can think of is tuning the stepper drivers, but I can't figure out why they would have gotten out of adjustment since I've never tuned them or done anything with them before.

 

Tentatively looking like I may have fixed it. A combination of increasing ventilation and tuning the steppers resulted in more reliable z axis travel. I suspect it was a combination of things (like anything this hard to diagnose).

Got my printer overhanging the edge of the worksurface, with a fan pulling cold air from the ground up to the case fan, tweaked the driver board to be right around 600mv and it's humming along pretty well. Sometimes get some janky layers but now it seems to be limited to stringing/artifacts from using PET-g since it is hands down the gooiest filament I have used yet. Now maybe I can get reliable prints to build the h-bot style printer I have most of the parts for (uconduit). That one will allow me to enclose it easily and run ABS out of it instead, though for the most part I am digging PET-G. takes some getting used to though for sure.

 

Preach, man. It's all boogers and string. Like a toddler.