Use of using extruder stall detection during filament loading?

[totalitarian]

Just setup sensor-less homing and noticed in the wiki you can use it for firmament loading. What would be the practical use of this?

[dc42]

@totalitarian said in Use of using extruder stall detection during filament loading?:

Just setup sensor-less homing and noticed in the wiki you can use it for firmament loading. What would be the practical use of this?

In systems with a long Bowden tubes, you ideally want to feed filament quickly through the Bowden tube until it reaches the hot end, and then extrude a little filament slowly to prime the nozzle. You can accomplish the first step by reducing the motor current (M913 then M400) and using a G1 S1 Ennn Fnnn move to feed filament in until the motor stalls.

[totalitarian]

That is a clever use! Could you also use it detect a filament jam?

[dc42]

@totalitarian said in Use of using extruder stall detection during filament loading?:

That is a clever use! Could you also use it detect a filament jam?

Unfortunately, stall detection doesn't work at low motor speeds, so extruder stall detection is likely to be useful only when using highly-geared extruders. You can set it up already, just configure stall detection for the extruder and select the "Pause on stall" action.

[Deltasquare]

Wasn't there some sort load detection implemented with the used TMC drivers? I can remember the TMC presentation videos including torque displays...
After some looking around I found this https://www.youtube.com/watch?v=Prw7wNa20Gk. Is there a way to export this information? For my testing purposes I want to be able to get feedback from the Extruder Stepper telling me how much load he is actually experiencing. By setting up a max torque level I would expect to avoid stalling by leaving a comfortable margin above...

[dc42]

@deltasquare said in Use of using extruder stall detection during filament loading?:

Wasn't there some sort load detection implemented with the used TMC drivers? I can remember the TMC presentation videos including torque displays...
After some looking around I found this https://www.youtube.com/watch?v=Prw7wNa20Gk. Is there a way to export this information? For my testing purposes I want to be able to get feedback from the Extruder Stepper telling me how much load he is actually experiencing. By setting up a max torque level I would expect to avoid stalling by leaving a comfortable margin above...

Load monitoring is tied in with stall detection in the TMC drivers. The M122 diagnostic report includes the minimum and maximum load reported by each driver, in the form of SG min and max values seen since the previous time that M122 was run. See the Trinamic datasheet for the meaning.

[Deltasquare]

Thats very interesting, as I have tried the command before and tried yet again.
Results are as follows:

Supply voltage: min 24.0, current 24.4, max 24.7, under voltage events: 0, over voltage events: 0, power good: yes
Driver 0: ok, SG min/max 0/1023
Driver 1: ok, SG min/max 0/173
Driver 2: ok, SG min/max 0/1023
Driver 3: ok, SG min/max 0/1023
Driver 4: standstill, SG min/max not available

Then I tried it again after a short while:

Driver 0: ok, SG min/max 0/157
Driver 1: ok, SG min/max 0/171
Driver 2: ok, SG min/max 0/1023
Driver 3: ok, SG min/max 0/1023
Driver 4: standstill, SG min/max not available

I interpret this in mA, so in the first example 1023 mA and 173 mA of current respectively. In the software I have following setup:

M906 X1000.00 Y1000.00 Z1000.00 E800.00 I30 ; Set motor currents (mA) and motor idle factor in per cent

(I expect a overshoot of 2.3% to be OK.)

The machine being a Delta, I would have expected 3 Drivers, supposedly 0/1/2, being the towers A/B/C and Driver 3 being the stepper, a standard Titan in my case.

So if I interpret this the right way the motor current maxes out quite regulary on all drives including the extruder. And I would think this is not supposed to happen.

So I expect my best course of action to be lowering the speed or acceleration(?) or jerk(?) for now in order to leave 20% of buffer between the topmost available current (1000mA), or to adjust the current, but staying 20% below the stepper motor's max current as explained here:
https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors#Section_Rated_current
Please verify whether I interpret this data correctly and whether my course of action is justified.

Is there a command to export solely those driver values from the TMC2660?

However I do not understand why the min/max changes. Isn't it supposed to stay the same? Is it only taking the min/max for a certain time period? How long is this time period?

[dc42]

The min/max is over the period since you previously ran M122, or since power up if you haven't run M122 before