Here is my Vref experiment. I printed the same part with only the Vref value changing. Started at Vref 118, then went to 100, 80, 60, 50, 45 and 40 at which point my part failed to firmly point the raft and failed. Visually, it looked as if the filament was just laid on the print bed instead of "planted" on the bed. Also the extruder started to sound different, like it was weak or something. I'm printing a quadcopter frame right now looks great so far but, the raft at one corner did lift off the bed about 1 mm. I'll let it finish but I think I'll print the rest of this frame at Vref = 60 to see if the raft will start acting right.

Tks, Roger