Impossible to set extruder micro stepping above 16ms

observatoer

I understand, if I setup E to 32 and ask by M350, to get the correct steps/mm wich would be in this case 1644. But, it is giving me 822 which is wrong for E32. And I get under extrusion.
Interesting for me, the values for X, Y and Z are calculated and displayed correct for X32, Y32 and Z16. Just not for E.

The stepper can handle up to 256 micro steps and reports the astronomic step count correctly, if I correct the initially wrong handled E value. No under extrusion. Just questionable, if it's really extruding wis 256 micro steps or just reporting a value.

droftarts

@observatoer

<<<<< startet with this config.g
M92 X200 Y200 Z3200 E822
M350 X32 Y32 Z16 E32 I1

This is what you said it is set to in config.g. If you send M350 E32, nothing has changed, so steps per mm are still 822. When you sent M350 E64, the steps per mm were correctly doubled. This isn’t the firmware getting it wrong!

The stepper can handle up to 256 micro steps

Of course it can. At slower step rates. But microstepping beyond 16x is, in general, pointless. The spec sheet for your motor says the step accuracy is 9 degrees +/- 5% which is pretty standard. That means that there’s a 10% swing in accuracy at FULL step. It’s why Gecko drives only use 10x microstepping; you won’t get any more accuracy from the motor by increasing microstepping. However, using interpolation is worth it, as the driver can smooth the transition between steps.

and reports the astronomic step count correctly

Do you mean the Duet reports the step count? The motor definitely doesn’t.

If you send M122 while printing, you can see if the motor is skipping steps. Look at the ‘Driver’ lines, eg:


Driver 0: standstill, reads 37420, writes 12 timeouts 0, SG min/max 0/0
Driver 1: standstill, reads 37422, writes 11 timeouts 0, SG min/max 0/0
Driver 2: standstill, reads 37422, writes 11 timeouts 0, SG min/max 0/0
Driver 3: standstill, reads 37422, writes 11 timeouts 0, SG min/max 0/0
Driver 4: standstill, reads 37423, writes 11 timeouts 0, SG min/max 0/0
Driver 5: standstill, reads 37423, writes 11 timeouts 0, SG min/max 0/0

The ‘SG min/max’ shows the minimum and maximum torque on the motor. If ‘max’ is 1023, the motor has stalled/skipped steps.

The issue here is that you have a pancake stepper as an extruder motor, with high inductance, that cannot step fast enough for the speed you want to print at, when you increase the E steps per mm. Get a more appropriate motor if you want to use high step rate and fast speed.

Ian

observatoer

@droftarts Thank you Ian. Is there any specific motor you would recommend for this application?

droftarts

@observatoer I don’t really know what you’re trying to achieve. Faster speeds? On an extruder there’s many other limitations, eg how quick you can melt filament. Higher accuracy, ie more steps per mm? Gearing down the extruder would be a better bet than increasing microstepping for the reason I said above, but you may lose high speed. Both? Good luck!

Ian

observatoer

@droftarts In the first place, I would really like to understand the behaviour of this software. Not more and not less.
As per description, if I set the M92 line for the correct steps at 16 micro step, I can change the steps/mm by typing M350 plus the command and value for X, Y, Z and E.
This is what I have done with this line:

M92 X200 Y200 Z3200 E822

These are the correct steps for a rate of 16 micro steps.

The next line in config.g is this:

M350 X32 Y32 Z16 E32 I1

I understand, the M350 command adapts step rates other than the baseline 16 in M92 to the mentioned values.

If I then type M92, I shall get the new calculated values for X, Y Z and E. Correct?

Why do I get the correct new M92 value vor X(=400@32), Y(=400@32) and Z(=3200@16) and an wrong Value of E. It shall be E1644 (for the requested 32) and is reported as E844.
Is there a difference, why these values are reported like this?

And regarding the stepper; I did reduce the current to 500mAh but this did not change anything regarding the above mentioned behaviour. Sorry, if I cannot describe it any better,

droftarts

@observatoer right, I see where the problem is. If you set M92 and M350 in config.g, that’s the values used. Even if M350 is after M92, the M92 definition is not assumed to be at 16x microstepping. It would be strange to explicitly set something in the config.g, and for the firmware to then alter it. If you exclude M350 from config, or the E parameter, I would expect it defaults to 16x.

Any subsequent M350 changes M92. I appreciate this is not clear in the Gcode entries for M92 and M350.

Edit: the configuration tool puts M350 in config.g before M92. Though I think the order doesn’t matter in confi.g.

Ian

observatoer

@droftarts OK. I refer to https://duet3d.dozuki.com/Wiki/Gcode#Section_M350_Set_microstepping_mode

and this description:

When M350 is processed, the steps/mm will be adjusted automatically to allow for any changes in microstepping. Therefore you can either:

a) Set Steps/mm correctly for the default 1/16 microstepping, then set the microstepping to the desired amount using M350:

M92 X80 Y80 Z400 ; set axis steps/mm
M92 E420:430 ; set extruder 0 and 1 steps/mm
M350 X128 Y128 Z128 E128:128 ; set microstepping
or

b) Set the microstepping using M350 and then set the correct steps/mm for that microstepping amount:

M350 X128 Y128 Z128 E128:128 ; set microstepping
M92 X640 Y640 Z3200 ; set axis steps/mm @128 microstepping
M92 E3360:3440 ; set extruder 0 and 1 steps/mm
Assuming that in the first example the microstepping was initially at the default x16, both the above examples result in the same steps/mm settings.

Could you suggest me the two lines for M350 and M92 who will work?

Edit: I have now played with every thinkable combination and variation of microsteppings. One common thing happens:

Regardless of any previous setting (verified in the console), as soon as the print starts, the steps/mm for the extruder are reset to 822.
All other steppers keep the right values as defined.

PS: I got the hint regarding the adjustment of the micro stepping from dc42 posting in this forum.

Phaedrux

Here's how I do it to keep it simple

M350 X16 Y16 Z16 E16 I1; set x16 microstepping with interpolation
M92 X80 Y80 Z400 E411 ; steps per mm set as if for x16 microstepping
M350 E64 ; alter microstepping for E axis

firmware now correctly calculates the new steps per mm required.

The key is to set everything for x16 first and don't change your M92, just have it set to work with x16. Then you can modify the microstepping after and it will correctly calculate.

fcwilt

@Phaedrux said in Impossible to set extruder micro stepping above 16ms:

M350 X16 Y16 Z16 E16 I1; set x16 microstepping with interpolation
M92 X80 Y80 Z400 E411 ; steps per mm set as if for x16 microstepping
M350 E64 ; alter microstepping for E axis

That matches the documentation with the exception that the docs say that x16 is the default so the first M350 should not be needed.

Are the docs in need of a correction?

Frederick

observatoer

@Phaedrux said in Impossible to set extruder micro stepping above 16ms:

Here's how I do it to keep it simple

M350 X16 Y16 Z16 E16 I1; set x16 microstepping with interpolation
M92 X80 Y80 Z400 E411 ; steps per mm set as if for x16 microstepping
M350 E64 ; alter microstepping for E axis

firmware now correctly calculates the new steps per mm required.

The key is to set everything for x16 first and don't change your M92, just have it set to work with x16. Then you can modify the microstepping after and it will correctly calculate.

I did exactly this and the machine reported exactly these values back which is correct. BUT, as soon as I start a print job, ONLY the value for the extruder E is reset to the 16 micro stepping value!
I checked all possible macros who could alter the setting during start, but non of them includes M350 or M92 values.

Something is definitely not working on my machine. I have changed the stepper already but as you see, same issue. I have also made a new sd card for the PI and did the latest test with these sw. I'm hesitant to build new config files at the moment.

Still same status: This new setting is not working properly on my machine.

JoergS5

@observatoer can you please check config-override.g and the start codes of the printed g-code file, maybe they are changing the E setting. Do the startup macros include M501 maybe?

observatoer

@JoergS5 Did this in the beginning of the test already. I cleared the content of it and omitted the loading in config.g.

JoergS5

@observatoer you seem to use IdeaMaker, is there something in the startup code which could change E?
https://forum.raise3d.com/viewtopic.php?t=12893
https://support.raise3d.com/ideaMaker/5-1-3-13-gcode-15-445.html
especially the "Extruder Switch GCode tab". Lot of places to change something...

observatoer

@JoergS5 Thanks for the hint, but I have removed all the default settings in Ideamaker from the start code and call a start macro on the duet3. This is all that remains:

M98 P"0:/sys/print/start.g" ; call start.g

M290 R0 S0 ;reset babystepping
M290 S-0.05 ; set babystepping height delta

M572 D0 S0.025 ;set pressure advance

And nothing in the extruder level. Totally empty.

JoergS5

@observatoer next I would check content of start.g and if babystepping or pressue advance change the E by disabling them.

observatoer

@JoergS5 Looks OK to me.

G29 S1 P"heightmap.csv" ; Load the height map from file and activate bed compensation.
G90 ; use absolute coordinates
M83 ; extruder relative mode

M98 P"0:/sys/G828.g" ; home if not homed
M98 P"0:/sys/G832.g" ; if not already leveled, level bed and re-home Z

; prime nozzle
G1 X0 Y0 F99999.0 ; Go home
G1 Z0.15 ; lower extruder

G1 X2 Y20 Z0.3 F5000.0 ; move to start-line position
G1 X2 Y200.0 Z0.3 F1500.0 E15 ; draw 1st line
G1 X2 Y200.0 Z0.4 F5000.0 ; move to side a little
G1 X3 Y20 Z0.4 F1500.0 E30 ; draw 2nd line
G92 E0.0

And the two calls look clean, too:

; G828.g
; Conditional variant of G28 home command.
; Homes all axes if not already homed.
if !move.axes[0].homed || !move.axes[1].homed || !move.axes[2].homed
G28

; G832.g
; Conditional variant of G32 bed command.
; Perform bed leveling if not already leveled.
if move.calibration.numFactors == 0 ; if leveling has not yet been performed...
G32 ; level bed
G28 Z ; re-home Z
else
echo "Bed already leveled. Skipping..."

JoergS5

@observatoer then I have no more ideas at the moment. I would remove and disable or comment out all and readd step by step to find the reason. It is also possible that there is a bug somewhere, because you have a lot of settings, macros etc. To be sure it's not IdeaMaker I would try a different program and g-code file first.

observatoer

@JoergS5 Thank you for your time and hints!

JoergS5

@observatoer sorry that I could not help. I think it's something trivial, a syntax error e.g., but I didn't see one.

Maybe M350 E16 I0 changing the E without interpolation behaves other than expected. You could try changing it to I1 as a test.

JoergS5

@observatoer I have one more idea: according the information in some threads like https://forum.duet3d.com/topic/4939/m350-not-working-wrt-m584/6 the order of the drives seem to play a role in the M584 command. In you config you have E first, so this may not be seen as an extruder drive in some code for other program parts. You could try changing
M584 E0 X1 Y2 Z3:4:5
to
M584 X1 Y2 Z3:4:5 E0