I was hoping someone could help me troubleshoot an issue with the top surface of my part (Pictures attached top(1st picture) and bottom (second picture)). First off I am running a relatively new Taz 6 bought in August this year and I did not initially have this problem. This print was done with Verbatim PLA at 30 mm/s, 210°C, 30% infill, 7 top layers. I get a surface pattern that appears to be 2 lines then a gap repeated. It also happens when I try other filaments.
I have done my best to calibrate the extrusion, to do this I have calibrated the extruder e steps by measuring the filament and extruding, but this was only a very minor adjustment really as it was already pretty good. I have also printed test extrusion pieces: 1) A hollow box that is one ‘line’ thick 0.5 and 2) http://www.thingiverse.com/thing:1622868. Both of these tests when I originally started using the machine suggested I needed to lower my flow rate to 0.95 to be accurate. As before the one ‘line’ thick would be 0.58 or so and the test piece would be slightly over extruded as well. So I have been using a flow rate of 0.95 and going to 1 does not seem to change the issue.
Googling this I have found that this pattern may be caused by backlash and to check the belt tightness, but the belts seem pretty tight (although I don’t know what I am comparing this to) and there does not seem to be any play in the extruder or bed movement. Adding additional top layers also does not help. I typically print with Simplify3D but the same issue is seen using Cura.
Does Anyone have any ideas as to the cause? Should I try and tighten the belts more?