I wast printing very slow to get a good finish on tubes that were about 1" in diameter (20mm/s). I jumped through all sort of hoops in flow rate and temp. I installed DVR8825 drivers set to 1/32 steps rather than the 1/16 on the Robo and began using filament with a minimum speed of 30mm/sec. I got great finish on flat vertical surfaces but on the 1" tubes it was awful. I also got messages that the log was stopped because of load. I decided to set the DVR8825's to 1/8 step instead of 1/16 or 1/32. All of a sudden the 1" tubes look very good. It seem the Processor just can not keep up which could explain many odd things. It may have a buffer because shot radii are fine. How can we put in a faster processor? 1/8 steps are really loud. Update: I have been printing a version of my product that changed the 1" tube design to a 1" octagon. I also changed back the stepper to 1/32 steps. The prints are now coming out gorgeous. Everything I thought I knew about filaments was wrong, I was working around a machine that could not keep up with the data rate. It looks like the timer that generates the steps is auto loading so it does not increase the processor load to go to 1/32 step. I am now printing at double the speed I used to. I am going to have to start from scratch learning new filament settings. The Robo should be no different than all of the other Arduino based printers. I am confused as to why this is happening but understand that a circle is a constant fast change in direction. The Arduino must convert the arc into a series of small straight lines that it can not keep up with.