Orbiter extruder not behaving as expected

General Discussion
1

Basic Information:

Printer Model: voron v2.4 350
MCU / Printerboard: octopus v1.1
Host / SBC rpi4
klippy.log
logs-20241019-100234.zip (86.0 KB)

I need your help again I am afraid. Not yet ready to solve all these niggely little things.
I completely rebuild the system from the previous owner. I tested the extrusion rotation using Ellis’ print tuning guide and from the klipperscreen the extruder worked as expected. I did find I had to remove the gear ratio statement from the config because it was trying to extrude way too fast. Never understood why we have multiple ways of expressing the mechanical setup anyway. If gear ratio is given and the motor is defined it should also result in correct rotation distance but in my cfg they both showed up??? Is something wrong here already I wonder?

After the removal of the gear ratio it worked perfectly and I set the rotation distance according the calculations from Ellis’ guide.

After the z offset calibration I tried printing a bed level print, just 5 square patches of one layer high.
Now the extruder does not work, it just clicks and rattles.
In the manual printer controls from klipperscreen, the extruder works until I set the 25mm/sec speed. That setting is too high and the extruder clicks on the last 10 or so mm.

What have I set wrong and where? I tried lifting the nozzle visibly away from the bed to make sure the z ofset calibration was not too tight to the bed, which can block the nozzle. But it did not make any difference.

EDIT:
I since posting tried a manual prime in mid air by sending G1 Y140 E10 F1500
to the printer. It worked perfectly so its something to do with the gcode from Prusa perhaps, or a macro in my system that distorts my wishes!

2

I think I solved it.
I found instructions for the LDO motor driven orbiter V2 which included firmware settings. In these it said interpolation = true and then a bunch of things I never seen before. After I set it to false and removed the crap below it works.

#driver_TBL: 0
#driver_HEND: 6
#driver_HSTRT: 7
#driver_TOFF: 4

What does this even relate to?

3

These are special settings in the TMC drivers that theoretically allow you to fine tune the TMC behavior to the respective stepper motor.

I and also others have spent countless hours including measurements with an oscilloscope to fine tune this on our printers and the common result can be summarized as follows:

  • No appreciable real-world benefit could be achieved
  • Making the driver’s performance worse is entirely possible

You will often see “generic” recommendations for stepper XY to set some of these values. In the best case they do no harm, in the “not so good” case it will make your stepper performance worse.

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