Finally got the MiltyKoss alpha unit back up and running. Trying a pivoting extruder and its working very well.
Extruder and stepper swivel to allow the bowden tube to be shorter and curvature to relax more. The feed is much better, especially retraction control.
The setup matches the natural twist of the filament from the spool. Holding the filament it follows the path the bowden tube naturally takes right to the effector, with the same natural twist from being wrapped around a spool. The ends of the bowden tube are much better aligned and relaxed, the filament is guided much more gently, set up to want to twist its way right into the print area with minimal friction.
Still a bit experimental, threw a 3/8" threaded rod on the side to be the pivot but the thing can be low enough the next will be just 250mm or less high, not extend to the top frame necessarily (might for looks and frame stiffness though). Going to try a center of gravity balanced pivoting in 2 axis mount design next since the ad hoc test is working nicely.
I am wondering how easy it would be to implement an extruder Z axis motor and steps in G code to keep an even shorter bowden at the same height relative to the print layer. Would solve a bunch of problems pretty easily with a $12 or less motor and a simple linear motion path requiring the most basic of guides with low accuracy requirements. Side placement allows some angled brackets from the corners and frame stiffening. It could have loose tolerances of steps and it would work ok as long as it homes between prints. If its under $30 or so for all the parts it seems worth it to position any extruder properly for better retraction control and relaxed bowden tube curvature with aligned feed in and out of the tube. An alternative to the complicated flying extruder with a slightly longer tube but a much simpler motion and arrangement.
