A medium issue I've found was the unwanted contact between the superstructure and the undercarriage regardless all the ball-bearings.
So i've added another dedicated flat bearing from igus. called "iglidur"
A .5mm thick plastic, easily cutable with a sciccor.
Glued direct onto the stainless steel with a combination of loctite 770 and 401.
After deburring and polishing the sprocket a first test
Then the optical improvement of the undercarriage begins
The front inner View is now this
And the side view before
and after the improvement
