Maximum extruder speed in config.g

lukas

Hi all, could someone please tell me if I'm thinking good or bad way.

In my config.g I have :

[[language]]
; Axis configuration
M92 X160 Y160 Z160			; Set axis steps/mm
M92 E2735:2735                       	; Set extruder 0 and 1 steps/mm
M201 X6000 Y6000 Z6000 E120		; Accelerations (mm/s^2)
M203 X25000 Y25000 Z25000 E3000		; Maximum speeds (mm/min)
M566 X1200 Y1200 Z1200 E40		; Maximum instant speed changes mm/minute

And part of my generated gcode is :

[[language]]
G1 F1800 X27.26 Y-1.76 E0.2738
.
.
G1 F1800 E-0.7
G0 F3600 X20.639 Y0.13
G0 X19.404 Y0.483
G0 X18.754 Y-1.581
G0 X18.812 Y-1.662
;TYPE:WALL-INNER
G1 F1800 E0.7
G1 F3600 X20.891 Y5.612 E0.37743

At the end of this part infill starts to print with a doubled speed than perimeters. Perimeters are printed well and of course non-printing moves are ok as well. I suppose that regarding the settings in config this 3000 vs 3600 is the cause of under extruded infill, right? How is the firmware interpreting the last line of code? Will it conduct the move at 3600 and extrusion at 3000mm/min despite the requirement of gcode? Or will perform the move and extrusion at speed 3000mm/min?

dc42

It will perform the move at 3600mm/min and adjust the extrusion rate to give total extrusion of 0.37743mm, provided that doesn't require extrusion at more than 3000mm/minute (which it doesn't).

lukas

Hello David, thanks for a quick answer!

As I'm reading your answer I've realized I forgot several factors to consider. Actually in the meantime I have tested with freed up extruder and cold extrusion allowed the max speed of the extruder and found out that at those 3000 and enough length of extrusion the motor stalls anyway.

In this case I suppose that the under extrusion of infill (missed parts of lines and strings) might be caused by insufficient acceleration of extruder, right?

dc42

You have a very high steps/mm (are you using a remote direct drive extruder?) so it's quite likely that 50mm/sec extrusion rate is not achievable due to motor supply voltage limitations. See https://duet3d.com/wiki/Choosing_stepper_motors#How_to_work_out_the_power_supply_voltage_you_need.

The acceleration of printing moves will be slowed down if necessary so that the extruder can keep up. So unless your extruder is skipping steps, this doesn't explain under-extrusion of infill.

lukas

Yes I was curious to try Nimble together with Smart effector as I’m really impressed by this combination!

I run STEPPERONLINE 17HS19-2004S1 with 24V@500ma but will calculate that tomorrow, too late for such a math for me