Continuing the search for good print

So, I ws not happy with this horizontal banding and very small waves on sides. so I went through a systematic and  looooooong test processing,  changing parameters and  hardware configuration one by one.  Now I have got more than 30 samples....
There is a good test on thingiverse for that : http://www.thingiverse.com/thing:277394
Most  samples are printer at  70mm/sec minimum

To summarize all changes I did:

• marlin parameters tuning, especially "Accelerations" and "Jerk"
• bed and Heater temperature
• filament flow extrusion rate  (80-120%)
• extrusion speed, retract speed
• infill 0 or 25%
• infill overlap
• perimeter after infill
• two types of motor controller (DRV8825, A4988)
• 2, 8, 16 or 32 bits motor substepping
• install the print on dampers to avoid vibration resonnance from the table
• belt tensioning
• install motors on antivibration support
• print on various places on the bed
• reinstall bowden vertically inside a cable chain
• add some grease to Z axis
• check all screws
• reinforce bed structure
• check and reduce extruder filament compression

and finally:

• replace sliders with bronze bearing tube by new slider with linear bearing LM8LUU
• replace Z axis leadscrew TR8x8 by TR8x2 

See pictures below, the black one has been printer with a small compact printer (minifabrikator)

Horizontal banding

I just spent lot of time trying to understand why I got horizontal banding on new parts with oboXL3D printer. Initially it looks like this:
:

 To compare with another print coming from Kossel printer (the orange part)

After many tests and assumptions like bad threaded rod on Z or not aligned, accuracy of XY, bad filament, bad heater, etc... I finally found the solution, thanks to a post found on a forum.
That post explains that this type of banding may come from the regulation of head bed temperature.

So, I followed the instructions and did this:
1/ uncomment #PIDTEMP Bed in Marlin configuration.h, to activate true PID regulation of the bad, instead of basic regulation (as defined by default)
2/ add correct values Kp,Ki,Kd (as computed automatically by Marlin). 



And it gave this, (on the left before tuning, on the right after tuning):

Thanks to those posts:
https://ultimaker.com/.../7907-horizontal-banding-on-um2
https://ultimaker.com/.../7613-firmware-surface-kwality...