@jay_s_uk : ok got it. you can mark this thread as Solved.
Thank you again!

@Phaedrux :

I have one machine on Duet3. I flashed 3.5RC4. after this extruder motor holds the torque but does not move on extrude commands. When i go back to 3.4.6, it extrudes fine. looks similar to what she's reported. Mine is dual extruder.

Can anyone confirm that 3.5RC4 with their system:
a) drives dual extruder fine
b) Can you test Resume after power failure & check if it resumes fine & does not print from an offset. (for me it occurs in Y direction only).
This happens with Duet2 wifi based belt driven machine.

https://forum.duet3d.com/topic/35334/jerk-acceleration-value-change-after-resume-apf/10?_=1713269800841

c) Can anyone suggest a few checkpoints ?

@jay_s_uk

I have attached the config file.
NOTE:

1. IF I run M115 B40 or M115 B41, I get positive response. both communicate well & the LEDs blinking is in sync. Same 3.4 beta3 on all boards.
2. Also I noticed, if I configure single board with B40 address and run the second extruder it works. So this confirms no problem with second motor or the board. Something in config is weird?
3. I haven't used G4 commands.
   NOTE: config is too raw, just for trial purpose. main purpose is to try running dual extruder via exp- 1XDs.
4. B40 (no jumpers), B41-XD : jumper on CAN-FD-OUT.
   Mainboard to B40 in -> B40 out -> B41-in-> Jumper on the B41-out.
5. I tried removing all jumpers too to see just in case it works.
   
   

(not able to upload file , so pasted images of the config).

@JayT :

This problem of extruder not working with Duet 3 is resolved after flashing RRF3.5.1.
Shifting problem remains same with Duet2, after resume on power failure.

@JayT
@dc42 : After few trials, we confirmed that since timer (job duration & the decrementing simulation time) starts immediately after pressing Print. Here if the bed & extruder temperatures are not attended yet, the warmup duration accounts only for bed heater time to attain target temperature. Extruder time to attain temperature is not accounted.
Hence we reach to condition (t<0) and simulated time completes displays N/A, while print is still running for few minutes.

2 methods to resolve this:

1. We account extruder temperature also in warm up duration
2. we start simulated time once Print actually starts (after warm up of bed & extruder)

What do you suggest ?
Do we evaluate time to attain extruder target temperature? Can you direct us to the code to change?

@modl :

Seam is not the issue. If we change this, it does not reduce gap.
Backlash does though. But even then I see the flatness at the top & bottom surfaces of the circle.

I also observed very less similar flatness in left & right most sides of the circle. Is this due to some slippage?

@droftarts @dc42 :

I further checked the setup & realize that the PT1000 sensor is 30mm in length with 4mm diameter. But the Biqu extruder slot for hotend & sensor is of 15mm.
This means half the sensor is outside sensor slot & not in contact with hotend.

Shouldn't this affect the PID learning & heater behaviour?

@droftarts : I understand your suggestion; for abs I might need 260degC.However, if I want to claim 300degC of extruder, I must tune it to that max limit. If I just tune to 210degC, then at times it will struggle to even reach 280/290degC . I plan to include chamber heater too.
My only concern is to understand this tuning well, so that there are not heater warnings/faults ., other wise on power up this predicted warning generates a doubt to user.
(I don't face this with bondtech set up, but with biqu extruder only).

• Does the position of heater & sensor matter?, Is it supposed to be completely inline with heater/sensor boundaries or a little protruding ? (I have used borosilica paste to fit the sensor well.)

NOTE: I user Duet 2 wifi board.

@dc42 :

Increasing R parameter, in my case, does not change the overshoot problem.
I tried decreasing R parameter, by 20-40%, then overshoot only reduces by 2 degC. i.e. earlier overshoot was 14degC, then it changed to 12degC, but cooling rate reduced.
What to do further , any suggestion?

Printer1:
M307 H1 R1.991 K0.759:0.048 D11.88 S1 B0 V23.9 E1.35 P7.5 I0.120 D44
This printer, does not give any warning on power up pf prediction, though overshoots at first by 14degC, but settles & then on fan on, temperature drop seen is just 4-5degC but manages reach target.

Printer2, same extruder, Biqu.
M307 H1 R2.457 K0.290:0.132 D11.88 S1 B0 V24.1 E1.35 P5.1 I0.0.085 D43.8

This printer, on power on, gives predicted temperature warning (511degC), temperature overshoots only by 6degC, but settles & on fan on, temperature drop behaviour is same as that of printer 1.

Why same sensor & heater type in same extruder type, behave so differently ? One overshoots only by 6degC, but other overshoots by 14degC.

note: Both tuned at same ambient, using "M303 T0 S300".

@Phaedrux :

For manual adjustment, it brings me back to the 1st post in this thread. Can you answer the following for me to try :
following links,
David suggests to increase 'R' paramater.
https://forum.duet3d.com/topic/31038/overshoot-and-really-unstable-hotend-temperature/2?=1721909615387
https://forum.duet3d.com/topic/31038/overshoot-and-really-unstable-hotend-temperature/2?=1721909615382

But literature says, to decrease in case of overshoot:
https://docs.duet3d.com/User_manual/Connecting_hardware/Heaters_tuning

Can you please confirm whether to increase or decrease "R" value ?

• Should I reduce P value ?
• Should I try tuning to 90% PWM?

@jay_s_uk :

Thanks.
I tried this "M303 T0 S300".
values after tune : M307 H1 R1.991 K0.759:0.048 D11.88 S1 B0 V23.9 E1.35.

On power up, prediction warning no longer appears.
On setting 210degC for PLA, temperature still, at first overshoots by 14degC but stabilizes after 2 mins. And on switching on Cooling fan, temperature drops by 5degC but heater manages to pick up. (in a nutshell, the I no longer get any heater warnings.

The question I have is :

• What does this feedforward method really does in the code to tune different than M303 H1 command?
• I have saved values in config-override.g, If I re-tune will the values be same or will it optimize further?
• Is this overshoot of 14degC due to thermal mass & sensor being little farther from heater area?

@jay_s_uk :

M303 H1 S300 P1

If I keep cooling fan at 0% fan during autotune, then I get the learned values as below & temperature with these values overshoots only by 6degC. BUT, the moment FAN starts, temperature drops by 5degC & I get a warning that predicted temperature can go beyond 500degC/700degC at times.
The values I get are:
M307 H1 R2.876 C238.464:338.464 D10.36 S1.00 V23.4 B0 I0

• If I auto-tune with FAN on in 2 phases & off in last two as per the procedure, Then the learned values cause an effect of overshooting by 15degC.

Image of hotend:

Hi,
I am using a 50W heater with Biqu H2 extruder. I am able to auto-tune heater at different part cooling fan speeds. (tried from 20% to 100% fan speed). But when I set temperature, even with 100% fan ON, I see extruder overshoots the target temperature by >15degC .
I found few links, but there is some ambiguity in the documentation literature & the forum link.

following links, David asks to increase 'R' paramater.
https://forum.duet3d.com/topic/31038/overshoot-and-really-unstable-hotend-temperature/2?=1721909615387
https://forum.duet3d.com/topic/31038/overshoot-and-really-unstable-hotend-temperature/2?=1721909615382

But literature says, to decrease in case of overshoot:
https://docs.duet3d.com/User_manual/Connecting_hardware/Heaters_tuning

1. Can you please confirm whether to increase or decrease?

2. I have tried increasing R parameter, still the problem of overshoot persists.

3. Should I try tuning to 90% PWM?

@droftarts , @dc42 : What do you suggest?

NOTE: I am using latest firmware & didn't face such problem with Bondtech extruders & slice engineering heaters.

@dc42 : Heater fault in my case was due to some interference from BLtouch wire., not due to RRF 3.5.1.. There was a change in wiring in addition to RR3.5.1 upgrade, but when I debugged further, the root cause was as stated.

@droftarts :
I see this is happening only with 1/2 versions of cura generated Gcode. If I use latest Cura version gcode, I don't see this problem much. However, I will see if stopping the log , helps anyway.
Also, I do see that this problem does not appear in previous versions of RRF. May be something is changed w.r.t certain gcode interpretation.

@Phaedrux : Please mark this as solved.

@Notepad :

On resume, at times I see in 3.5.1, I see heater fault "temperature rising too slowly". This happens when after resuming on power failure, I set extruder temperature to 210degC. NOTE: This happens only during this resume sequence with 3.5.X. It does not happen in 3.4.6 ,...