I’m having this same problem, but with Lulzbot brand ABS on the Mini Aerostruder. Tested using the same print about 15 times yesterday. Each time, it would print perhaps 10-20 layers, then grind out the filament.
I know all the typical causes of grinding, and tried all the typical solutions… I tried different idler tension from very loose to very tight, everywhere in between at 1/2 turn increments. I tried increasing temp. Cleaned the hob after every grind-out. Checked that temp is stable during extrusion, that heatsink fan is running and heatsink is cool. Priming flows freely, no pigtailing, no clog (even tried a second Aerostruder to eliminate possible nozzle/heater/thermistor issues). Filament is dry. E-steps are calibrated. Spool is turning freely.
I played around with retraction settings. Started with default CuraLE retraction, 1mm @ 10mm/s. I tried less retraction (0.5mm), more retraction (2mm), slower (5mm/s) and faster (15mm/s). None of that helped. Turning off retraction entirely solved the problem, but made for a messy print. The print doesn’t have excessive retractions – perhaps 5-6 per layer – and never in rapid succession.
The same part, printed with the same retraction settings, succeeds at 0.25 layer height. At 0.38 layer height it grinds out after a few layers. Also note that this part has 80% infill, so when printing infill a lot of filament is being extruded quickly – so back-pressure may be involved. Temp graphs shows stable temp during that, but I tried increasing temp anyway from 240c to 245c, then 250c, along with different idler tensions, but still had problems. I tried reducing infill speed to 40mm/s, but the problem still occurred.
Swapped in a second Aerostruder and experienced the same problem. After fighting it all day, I finally switched back to the Hexagon and had success first time.
Over the previous few days, I had run a bunch of PETG, PCTPE, and Ninjaflex prints through the Aerostruder – and never had a single grind-out problem. But all of those prints were also smaller layer heights, few retractions, and a bit slower (a lot slower with the Ninjaflex).
My current conclusion: The Aerostruder has a high tendency to grind out filament, at least when high flow / nozzle pressure is coupled with even a low frequency of retractions. I don’t see any logical reason for it, but that’s my experience so far. If there’s an adjustment or setting that fixes it, I certainly haven’t found it yet.
EDIT: Just ran a 2hr print, same filament, same 0.38 layer height, same idler tension, and this one had a LOT of retractions – but almost no infill. It completed fine, no grinding despite hundreds of retractions. So again, the problem seems to be retractions in combination with high volume extrusion, as seen with doing a lot of thick layer infill.