[UM2 Extruder pressure setting?]

The 'correct' position for the extruder indicator depends on when your printer was manufactured. Prior to March 1, 2014, the indicator should be in its highest position. After that, it should be in a central position.

Note that tightening the screw (moving it clockwise, as viewed from above) moves the indicator upwards.

When you talk about 'extruder skips' are you referring to the motor skipping backwards with an audible click (and a jump back of about an eighth of a turn of the motor shaft and knurled wheel), or are you simply referring to it grinding past the filament somehow, damaging it?

If its the former, then adjusting the idler tension in the extruder isn't likely to help much. Those skips occur when the motor simply can't push the filament hard enough to make it move. When that happens, the motor stalls, and jumps backwards. That is a good thing, insofar as the alternative is for the filament to stay put, and the extruder to keep turning. If that happens, then the motor will simply grind away the filament, to the point where it cannot grip it at all.

So, if you are getting the first kind of skip, then changing the level of grip on the filament won't make it better: the motor is already transferring all of it's grip into the filament, and it can't push hard enough. Reducing the tension in the extruder might allow the knurled wheel to grind past the filament, rather than gripping it, which will prevent the stalls (and the skips) but at the expense of damaged filament.

If what is happening is just that the filament is being ground away, without the motor skipping backwards, then adjusting the tension might help some, if it improves the grip on the filament, and lets more of the available torque be transferred into the filament.

Where the problem is the actual motor skipping, then the best solution is to eliminate sources of friction in the feed path (e.g., tightly curled filament, damaged Bowden tube, damaged teflon coupler, partially blocked nozzle) so that the filament can move, melt and extrude as easily as possible. If problems persist, then consider printing hotter, of at a lower volume per second (i.e., thinner layers, or slower linear head speed).

 

Great Explanation. Saved me a lot of confusion! Thanks @illuminarti