Unresolved Z axis Issues

Robo R1+ I am having issues where at some point on taller prints it looks like it starts to under extrude. I have adjust the filament diameter. and I am still having issues.

These are the same print (Calibration cube ) scaled x 2. One of the prints it's almost like the Z just stopped moving.

MatterControl 1.5 PLA TEMP 207 Fil Diameter 1.79 Extrusion Multi 1.08 infill 7% Speed 100mm/s outside 90mm/s infill

I get good adheasion, and it seems smooth when manually controlling the software.

 

Couple things can make sure you are not under extruding and that things are sticking. Clean and oil with some light 3-in-1 machine oil the smooth rods on the Z. Also take some oil drops down the leadscrews for the Z and run the Z axis up and down using matter control to work it all in. Also to make sure you are extruding correctly, you can do an extruder calibration. Video below to how to do this.



Now with that all said...put your extrusion multiplier back to 1, and slow your print down to 50 mm/sec. 100 mm/sec is very fast for these printers unless calibrated just right and even then you will improve quality with slowing things down. Going fast you also need to adjust temp up so that the extruder can extrude at that speed.