I would like to let my printers extruder make two extrude only movements, e. g. with following gcode:
M83; relative extruder movement
G1 E50 F20; 50mm filament with a velocity of 20mm/min
G1 E50 F100; 50mm filamet with a velocity of 100mm/min
With that command sequence the extruder extrudes at both velocities with deceleration to zero mm/min in between. Is there a way to extrude only at two different velocities with direct acceleration between both extrusion moves?
I’m not sure what you are attempting to achieve and so I’m not sure if Klipper can perform what you are trying to do without code modifications. Note that the instantaneous_corner_velocity setting limits the instantaneous velocity change between extrude only moves - Configuration reference - Klipper documentation .
I added a load cell to the filament feed unit and investigate filament thrust over extrusion acceleration and velocity. Therefore I am happy to let the extruder make single extrude only movements. It would be very interesting to see thrust between two extrude only movements with different speeds without decelerating to zero velocity in between. Maybe that could help improving pressure advance.
I tried to change instantaneous_corner_velocity to 1000mm/s and let the extruder move following commands
M83; relative extrusion movement
G1 X0 Y0 Z100 F5000; move to the left front corner
G1 X100 E25 F400; move 100mm to the right extruding 25mm of filament
G1 X200 E25 F800; move another 100mm to the right extruding 25mm of filament
Nevertheless between both moves the extruder slows down to zero velocity in between both moves. The following diagrams are from a test of an other machine (Voron 2.4). Between both moves the toolhead slows down to 0mm/s in between.
The instantaneous_corner_velocity setting places a limit on instantaneous changes in extruder velocity. If the toolhead is also moving, then it is also limited by the square_corner_velocity setting.
For what it is worth, though, I suspect you may be trying to push the printer too hard - I would not recommend dramatically increasing either setting on a real machine.
