These control pressure to prevent thickeneing of extrusion and this increasing quality. For this they slow down or even retract the higher the values get. L is for linear dependend on speed and K for nonlinear depending on speed. Search reprap forum for more details.
That said, I never could get it working successfull with any bowden setup normally used on deltas. The bowden adds so much way to extrude that the extruders can not successfully follow the movements that would be required. More likely is that you flex your filament so extruder stucks. This is more a thing for direct extruders with short way between motor and nozzle.
5) What other printer parameters need to be changed? MAX_JERK MAX_ACCELERATION_UNITS_PER_SQ_SECOND MAX_TRAVEL_ACCELERATION_UNITS_PER_SQ_SECOND ?
Key features of my printer:
Kinematics H-boot, working field 210х210х204, extruder bowden, tube length about 90 cm. The printer electronics is based on ramps 1.5 and arduino due, the extruder driver DRV8825 (32 microsteps) .
Comments
L can be estimated good with 3). Used it as well for my printers.
L Range depends on extruder type and distance motor-nozzle. Direct extruder are around 40 (at least my extruder is) for PLA.
No other dependencies.