Looking at the bottom of the cup, sometimes the extruded filament is thick, sometimes it leaves only small traces, or it is missing at all. Sort of extruded filament is not consistent. Mark the filament 10cm above extruder and you might check to see that sometimes it pulls the filament down, but sometimes you may notice the wheel is moving but the filament is not.
Probably hardware issue, e.g. your hobbed bolt is partly covered in material shavings already, and is slipping in that part, producing the "missing lines" pattern. Probable causes that lead to this can be: motor current too low so motor doesnt have enough torque + springs tension too low. Clean the bolt, increase motor current, tighten the springs much more than they were and try again.
Or maybe you are trying to extrude too fast, e.g. faster than the extruder can physically do it. Which leads to shavings like that soon to cover the hobbed area. Slow down, and if you have a firmware with MAX_e_steps_permm, experiment to find that value, in order to make sure that it will be compiled with lower than that.
If it feels like there is no end to it, then maybe the filament is too thick for where it has to go and it gets stuck somewhere on the path. E.g. 3mm filament abs in a 3mm hole tends to get stuck when approaches the heated part. Depending on your hot end you might increase that hole/path diameter from 3.0 to 3.2 but then might get in trouble with 2.7 filaments which if inconsistent can get down to 2.5 on some segments. If you have more than one type of filament, measure their diameters with digital caliper and try with the smallest diameter.
Edited 2 time(s). Last edit at 10/14/2011 02:47PM by NoobMan.
