Testing Microstepping and found the real culprit...

Addendum to my last post...

So I tried a quick and dirty test where I marked the filament in 10 mm increments I changed the microstepping levels in motion.g and the step count per mm so that channel 2 and 3 were different, power cycled the machine to set the change and tried extruding and retracting 20mm increments at 60 mm/second. 

There was no distinguishable difference in speed of movement. But I should also note that the speed of the movement doesn't even approach 60mm per second. I may go back and try shooting high speed video at some point but my guess is it tops out at 15 mm per second. From a retraction standpoint that is a problem.

It turns out there is another setting in motion.g that sets the maximum speed of the extruder to 600 mm/minute. Duh! No wonder I am having stringing issues. that is limiting all of the exturders to 10mm per second. No where near what is typically used for retraction moves.

So now the test is to see if these motors can handle actually being run at 60 mm/sec on retractions...