I'm extruding at 1mm width * 0.6mm height * 50mm/s = 30mm3/s That's well under the supposed 40mm3/s max for the Volcano. The 40W heater just can't keep up. I've calibrated PID (at 44% parts fan and 245C) and then beefed up the P and I numbers some more. I cut the parts fan altogether. When extruding at 20mm/s print speed no probs. At 50mm/s no good. Checking the HE0 LED on the Rumba it's clear the 40W heater is working flat out. But nozzle dips from 245C to 239/240C. And was not pleased to find a Thermal Runaway (230C) after 5hrs 50 and just 10 layers before the end. Basically it can cope if there's some travel motion going on, but the moment you get a number of layers of constant extrusion, that's it. ;( Can we fit a more powerful heater? Don't see anything in the e3d store?