Unchangeable extrusion speed when "Advance" enabled
Hi,
I have encountered the following phenomenon with both of the latest Repetier FW versions (0.91 Rev.8 and 0.92):
I have recently switched from Azteeg X3 Pro board (ATMEGA 2560) to a RADDS board (ARM). The firmware is running nicely, except a scenario where the advance algorithm is enabled. Whenever I set the linear advance factor in EEPROM to any value other than 0 (i tested from 0.001 to 100), the extrusion speed is always the same. In other words, there is no difference between slow and fast extrusion from the Repetier Host - both buttons produce the same (slow) extrusion rate. However, when advance_l =0, the buttons DO produce different extrusion rates just as it should (in my case 2mm/s and 10mm/s). This is quite annoying, since e.g. the infill is severely underextruded which is usually printed at higher speeds.
Any ideas what could this be?
Thanks for help!
andi
Comments
Hello,
Here are some interesting results I observed using the latest update of Repetier FW (0.92.3).
I measured the step and direction signals of the extruder using my logic analyzer and here are the results. In particular, I looked at how the signals look during the deceleration; in this test I printed single line at 80mm/s and then slowed down to 40mm/s over a single straight path. Here is the GCODE of the test (pre-amble commands for heating, homing, etc. omitted here):
; Move to start
G1 X210 Y210 Z3.8
; extrude L1_1
G1 X210 Y190 E0.732 F2400
; extrude L2_1
G1 X210 Y110 E3.659 F4800
; extrude L1_2
G1 X210 Y90 E4.391 F2400
Now here are the results with and without advance algorithm enabled:
1) WITHOUT advance algorithm (advance linear = 0):
(Figure 1).
Observations:
The path planner does not seem to be working as intended. The extrusion slows down towards the point of the speed change where the speed is then the smallest and then accelerates to the speed of the second segment (40mm/s). I believe that there should be no phase where the extrusion is accelerating. The XY-movement is along a straight line!
2) WITH advance algorithm (advance linear = 10):
(Figure 2).
Observations:
Very weird behavior off direction and step signals. I cannot really follow what’s happening here…
Could you elaborate on the above observations? Thanks!
Andi.
1) WITHOUT advance:
In Figure 1 above you can observe the same behavior as noted in the previous post regarding the deceleration and acceleration of the extruder step signal. Furthermore, one can observe that the step signals of A and B motors are not distributed equidistantly. Since individual step signals of the AB-motors are not visible in the image resolution, and to recognize any patterns I plotted the duration of step-signal periods (i.e. Step_high + Step_low timing) as a function of time in Figure 2:
(Figure 2.)
One can see on Figure 2 that the A motor is decelerating and then accelerating – the same behavior as we observed for the extrusion. This happens despite the fact that the movement is happening along a straight line in the Y-direction…
Please let me know if this helps and if any further tests may help!
Best,
Andi.
I have the same problem as described from Andi in the beginning, but with a Rumba board (ATMega 2560) and a mixing extruder (1/16 stepping mode, 312 Steps/mm). An update to the newest firmware did not bring any change, the extruder(s) are running with a maximum speed of f400. Do I have to change anything in the frequencies? That's unfortunately something I know nothing about.
Thanks in advance,
Svake
yes, that is right, it's 6,66mm/s. If I don't use advance then I can go up with the feeder speed until the stepper motor falters, what happens with about 50mm/s?. I have tested this once, but forgotten. So it should be faster then 6,66mm/s, even with advance?
Thanks,
Svake