I blew-up the heating resistor in my J-Head so while that was down awaiting parts I thought I’d take another stab at getting the QU-BD extruder to work.
The first step was a modification to the filament drive designed by whosawhatsis ( http://www.thingiverse.com/thing:15718 ). Fortunately I happened to print these parts before my J-Head croaked so I had them around to test with.
Next I was happy to find that since my last attempt at getting these extruders to work someone had published a resistor table that they could demonstrate good results with.
I updated my firmware settings with this table and made the necessary steps- per-mm adjustments and then re-ran the PID autotune.
After several tests, the exact same problems from my earlier attempts to get these to work exist. I tried one more time with a more extensive resistor table to make sure I exhausted every option.
I ran the PID autotune again and flipped over to Google to see if I could find any more nuggets of wisdom that I might use to get something useful out of this hardware when I noticed a stream of smoke pouring out of the nozzle. Apparently the resistor table I used wasn’t quite right and the hot-end was on it’s way to meltdown. This is when I noticed that setting the temp to 0 doesn’t override the PID tuning procedure and it was time to hit the E-Stop (i.e., pull the plug).
Thus ends another chapter in the futility of trying to do something useful with the QU-BD extruder. I guess I’ll be setting the printer aside until my replacement parts arrive…