Buffer problem?

Veti

M350 X256 Y256 Z32:32 E32:32 I1 ; configure microstepping with interpolation

there is your problem. you are overloading the cpu.

change this to x16 with interpolation for all axis.

Tinchus

Ok, will try that change. What Im losing by using 16, and not 32 for example? I was running on 32 before, but I had some ringing wich disappeared when I switched to 256

ZipZap

You are not loosing anything.
When microstepping on the Duet is configured to x16, then the TMC-driver will do the interpolation to x256 from there. In this case, you are outsourcing the calculation to the TMC.

Vague knowledge (please correct, if wrong):
When using x32 on the Duet, the interpolation on the TMC is disabled.
So the movement would be "rougher" on this setting -> possible Ringing on a certain frequency?

/Julien

dc42

Also, you should upgrade the firmware on your Duet 3 to 3.1.1.

Veti

@ZipZap said in Buffer problem?:

When using x32 on the Duet, the interpolation on the TMC is disabled.

Thats only true for the duet 2 wifi/ethernet.
The Duet3 can do interpolation at all settings.

ZipZap

@Veti said in Buffer problem?:

The Duet3 can ...

My bad, didnt check his hardware.
So to be clear: When microstepping on the Duet 3 is set to anything higher than x16, the TMC will still do the interpolation to x256?

Veti

@ZipZap said in Buffer problem?:

So to be clear: When microstepping on the Duet 3 is set to anything higher than x16, the TMC will still do the interpolation to x256?

yes. the duet maestro can do this as well.

Tinchus

thanks everyone for the help. Going down to 16 for my microstepping, eliminated completly the sttuttering. After that, I also upgraded to 3.1.1
My problem now is that I ran the same gcode, and now I have ghosting all over the print and it is very very constant.
Im looking now into acceleration settings but Im wondering why this ghosting was not present at all with the previous setting of 256 microstepping.
Ideas?

dc42

Do you have interpolation enabled in your M350 command?

Tinchus

Yes interpolation eis there:

M350 X16 Y16 Z32:32 E16:16 I1

Phaedrux

Can you post an image of your ghosting artifacts?

Ghosting is usually caused by an interaction of print speed, acceleration, and jerk, assuming there is no excessive mechanical slop to blame in the first place.

How fast are you trying to print?
Is the slicer adding its own acceleration and jerk values?
Have you tried tuning your acceleration and jerk values?

When using x256 microstepping you were likely not hitting your requested print speeds, so now that you're printing faster your jerk and acceleration values may need to be tuned again.

You may also want to consider tuning Dynamic Acceleration Adjustment

https://duet3d.dozuki.com/Wiki/Gcode?revisionid=HEAD#Section_M593_Configure_Dynamic_Acceleration_Adjustment

Tinchus

@Phaedrux
Mecanical slop should not be a problem, axis movements are super smooth.
The tests prints were done at 100 mm/s
Slicer is not adding any accel or jerk settings (I have that feature desabled)

The test prints were done using very conservative values: kerk is arounf 15mm/s and acceleration I have tried even 600 mm/s.
My build a corexy, 40X40mm aluminium extrusions, the frame is super strong. I have hiwin linear guides on top of them. It is a very strong frame, it should tolerate acceration higher than this. Even so, I have print the pictures with 1000 mm/s2 accell, you reccomend less than that?
If you see in the pictures, the problem is that ringing goes all the way the print, is not just at the beginning or ending the corners.

Before switching to 16 (256 microstepping), no ringing:

After the switch:

Regarding reaching the speed: of course it is a posibility, but to my eye, the speed is the same , just that the sttuttering is not present now.

Question: it is not very clear in the picture, but the ringing you see, that ringing goes from the very begining of each curved path till its end, and those paths are like 80/100 mm long. All the way there is this waivy artifact. Could this be caused by something wrong with my motor extruder configuration? acceleration/jerk of my extruder?

Thanks in advance

Phaedrux

That definitely doesn't look like traditional ringing which would occur on a sharp direction change like a corner.

You may be right about it being extruder related.

Is that a single wall print? If the speed is higher and more consistent now, it could be related to insufficient cooling.

How many extruders do you have? Your config has a mix of single and dual extruder values. If you only have a single extruder, remove the double values for E.

M584 X0.0 Y0.1 Z0.2:0.3 E0.4:0.5 ; set drive mapping
M350 X256 Y256 Z32:32 E32:32 I1 ; configure microstepping with interpolation
; M92 X160.32 Y160.32 Z3200.00:3200.00 E827.22 set steps per mm
M92 X1285.13 Y1285.13 Z3200.00:3200.00 E827.22 ; set steps per mm
M566 X900.00 Y900.00 Z300.00:300.00 E2400.00 ; set maximum instantaneous speed changes (mm/min)
M203 X18000.00 Y18000.00 Z240.00:240.00 E1200.00 ; set maximum speeds (mm/min)
M201 X1000.00 Y1000.00 Z20.00:20.00 E500.00 ; set accelerations (mm/s^2)

Are you still using x32 micro steps on the extruder? Use x16 to establish a baseline. It looks like you're already using a geared extruder, so increasing the steps per mm beyond ~400ish isn't going to gain you anything.

For the extruder speed values try

M566 E3000
M203 E6000
M201 E3000

I'd also experiment with slower print speeds.

Have you PID tuned your heaters yet?
Are you sure your thermistor values are correct?

Take a look at this extruder calibration guide to find your volumetric extrusion limit which you can use to optimize your print speed.

https://duet3d.dozuki.com/Guide/Ender+3+Pro+and+Duet+Maestro+Guide+Part+4:+Calibration/40

Tinchus

@Phaedrux , no, I followed the forum recommendatios and changed all my steppers to 16 microstepping, interpolation activated. The only thing I left in 32 is the Z axis only because the calibration took me a lot of effort and I dont want to calibrate those steps again if possible. But extruder s are with 1/16 and that is the microstepping used for the print test in the pictures.
The pictures: yes, it is a single wall, vase mode print.
I have 2 extruders

My config in that section is this since I changed the microstepping:
M584 X0.0 Y0.1 Z0.2:0.3 E0.4:0.5 ; set drive mapping
M350 X16 Y16 Z32:32 E16:16 I1 ; configure microstepping with interpolation
; M92 X160.32 Y160.32 Z3200.00:3200.00 E827.22 set steps per mm
M92 X80.16 Y80.16 Z3200.00:3200.00 E428.25 ; set steps per mm
M566 X900.00 Y900.00 Z300.00:300.00 E450 ; set maximum instantaneous speed changes (mm/min)
M203 X18000.00 Y18000.00 Z240.00:240.00 E1200.00 ; set maximum speeds (mm/min)
M201 X1000.00 Y1000.00 Z20.00:20.00 E500.00 ; set accelerations (mm/s^2)
M906 X1500 Y1500 Z900:900 E1000:1000 I30 ; set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

My extruder steps are now half than before.
Regarding PID: yes, I did an autotunning precedure. I have ? mark there because I have a mosquito hotend with a hight temp thermistor from sliceenginnerin. At ambient temperature my reading is 35 degrees, when actually room temeperature is 24/25 degrees celsius. So that initial reading is not ok. The values I used for the thermistors are the ones the online duet configuration toll gave me (I used that configuration tool as startin point for the rest of my config).
Could be a cooling problem and not really be a ghosting problem?
I will repeat the print with lower temperatures.
Question: the high temp thermistor curve is tested and approved by duet already or it is somehow still "to be tested?
Thanks in advance for the help

Phaedrux

@Tinchus said in Buffer problem?:

M92 X80.16 Y80.16 Z3200.00:3200.00 E428.25 ; set steps per mm
M566 X900.00 Y900.00 Z300.00:300.00 E450 ; set maximum instantaneous speed changes (mm/min)
M203 X18000.00 Y18000.00 Z240.00:240.00 E1200.00 ; set maximum speeds (mm/min)
M201 X1000.00 Y1000.00 Z20.00:20.00 E500.00 ; set accelerations (mm/s^2)

If you have 2 extruders then you are missing the second E value for these commands.

By contract, your Z axis only needs a single value since both motors MUST be the same. This isn't the case for extruders since they aren't acting in concert for a single E axis, they are independent axis by nature.

So, remove the double Z axis values, you only need 1, and add a second value for the E axis because you need both.

Just to be totally clear

M92 X80.16 Y80.16 Z3200.00:3200.00 E428.25

would become

M92 X80.16 Y80.16 Z3200.00 E428.25:430

@Tinchus said in Buffer problem?:

ambient temperature my reading is 35 degrees, when actually room temeperature is 24/25 degrees celsius. So that initial reading is not ok

That's to be expected with a high temp thermistor. Since you're using the values provided by the config tool for the slice thermistor you should be fine and your printing temps should be accurate.

It will be interesting seeing your results from slower print speed and different temperatures after finding your maximum volumetric flow rate.

Tinchus

Ok, I did the max flow test, I have a solid 7mm/s of ABS extrusion at 240 degrees celsius. Doing the maths, that gives me 16.8 mm3/s

Phaedrux

Alright, so using 16mm3/s you can find a max print speed based on your chosen height and width.

Max Suggested Speed = Volumetric Limit / ( Layer Height * Extrusion Width)

So assuming 0.4 width and 0.2 height you could print at 200mm/s and maintain the flow rate. However, it's going to depend on the part being printed whether you're able to cool it fast enough or print the details at that speed.