After the following video was shot, I did some careful stopwatch work and found is actually running at approximately 3.5 times than reported. This means that in the video it is actually running at 56mm/s perimeters and infill at 140mm/s at 1400mm/s^2 acceleration.

This is because the firmware calculates the speed at the motors, rather than at the end effector. The moves of the print head a proccessed in segments per second. The arduino struggles to calculate more than 40 segments per second due to the math thats required to run this. I plan on moving from Marlin firmware to Repetier firmware as Repetier is written with speed and efficiency in mind. Hopefully this will allow for more segments per second and so more precise movements.

At speeds over ~50mm/s actual, backlash becomes visible. I think I've identified where it is coming from mainly:

• Frame flex (lifting the printer onto another bench throws the bed off from level)
• Flex in the stepper pulley motor shafts, as the pulleys are mounted too far from the motors.
• Flex in the wood chipboard mounting plate
• The upperarms are quiet rigid as are the pulley mounts. I think fixing the above mentioned issues will help a lot.