Suggestions for print coverage issues

#1
Basic printing is working but getting coverage issues. This was a 4+ hour print. Ignore the stray strands at bottom; those were from non-supported arch. Rest of object printed ok.

Is this a clogged printhead?


Confirmed its not the model by printing w/ other printer.

gMax in green, Vision 3D in red


Suggestions on where to start?
 

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#2
Could be a few things.

When I first setup my printer my filament was getting caught in the filament shaft as in this post. When this happened I over tightened and then over loosed the extruder lever and overvolted the extruder motor. Both of these things can cause what your seeing here.

I ended up turning the voltage of the extruder motor all the way down and started turning it back up and pinched as it was rotating (without any filament loaded). Once it was strong enough not to skip through a firm pinch I haven't had to touch it since.

After about 20 hours printing (one 16h print and a few shorter ones), I had roughly the same issue again. What happened was my extruder lever was about to fall off and was not holding the filament securely.

Another thing that can happen is if your filament gets pinched in the spool. This almost happened to me once, and I am not sure that is what happened here. If you swap out your filament and are not paying attention it isn't difficult to half hitch the roll.

Also you can use http://gcode.ws/ to check your gcode before printing. By doing this you can see if slic3r is doing anything wonky. Like printing a bottom layer parallel to the support interface below it (bad times). Check the 'Emulate extrusion width' option to see if there are gaps... The print estimates are about half the time I have seen but the weight of material used seems to be close.