Configuring Extruder MAX Feedrate, Start Feedrate, and Acceleration

SOLONOZ

What is the procedure to configure these settings so that I get the most speed out of my feeder without inducing skipping/grinding of filament.

I am using .85A .9 degree Steppers that output 59 oz-in (0.42 N-m) holding torque. They are ran by a TMC2100 stepper driver with the POTS configured to provided the OEM specified amount of power for the motor, not more and not less.

Currently my Repetier firmware settings are:

MAX FEEDRATE: 35 mm/s
START FEEDRATE: 5 mm/s
ACCELERATION: 3000 mm/s

I am getting some issues with skipping and grinding what should I adjust?

Repetier

These are not very progressive values. The problem is what happens and when. When you extrude to fast you always get one of these problems. Heater needs to melt filament and only hot filament can be pushed through nozzle. So for extrusion max. speeds of around 3mm/s are not so uncommon. max feedrate is only interesting for retractions and should not skip steps or loose grip. That is what you you really adjust with acceleration and max feedrate.

SOLONOZ

Extr. Max Feedrate: 35.000 mm/s
Extr. Start Feedrate: 5.000 mm/s
Extr. Acceleration: 3000 mm/s

Retraction Speed: 55mm/s

X-axis max. feedrate: 250.000 mm/s
Y-axis max. feedrate: 250.00 mm/s

X-axis acceleration 1000.000 mm/s
Y-axis acceleration 1000.000 mm/s

I am not sure if I didn't specify my settings correctly so you would understand my situation. So what your saying is set my Extr. Start Feedrate at 3.000 mm/s and adjust my Extr. Max Feedrate based on how fast I want my retraction to be, so if I want to set my Retraction Speed to 55mm/s I need to make sure not to restrict it with the Extr. Max Feedrate? So I should turn the Extr. Max Feedrate: 55mm/s so that my Retraction will truly run at 55mm/s ?

Thanks for the help. Also any other comments or advice you might have are very much welcome.

Repetier

Yes, max feedrate is more for retraction. During print the speed is coupled to xy move speed and depends on that and layer height. So if you need to limit real extrusion you need to tell slicer about that limit by reducing xy print speed or layer height. It is proportianal to xy speed * layer height.