Hello,

first of all thank you in advance for your help. I have troubles with my printer for a few months now and i have tried a lot, but without any positive results. That's why i thought to post in this forum and ask for your help, maybe someone here is able to help me.

Getting to my problem:
I'm a proud owner of a delta-printer, the Anycubic Kossel plus (Bowden, Heated bed, linear Rails). The printer is upgraded with a Duet Wifi board and Prusa motors and until a few months back the printer has woked excellently.
The only issue was that the z-seam was too huge and was ruining my tollerances, so i have played a little with pressure advance. That had worked fine for two prints but suddenly the prints were looking verry strange. Turning off the pressure advance did not affect the issues (see the following picture).


The occured errors were mainly ugly z-seams and randomly but systematicly growing errors in the outer and inner walls. (In the pictures you can see PA-Tests with alternating PA-values from 0 to 4 and from 4 to 0 in heigth)


Because of the sudden occurency of the errors my first guess was the slicer (at this time i was using Cura 4.4). But because of the same errors showing with G-Code i had succesfully printed before i could tell that it is not the slicer. (Now i have updated to Cura 4.7.1, wthout any difference)

Because it could not be the slicer my next guess was that it had to be an issue with the printer. So i have changed the nozzle and checked my bowdentube (clean). The errors where still occuring.

The next step was to update the firmware of the Duet Wifi board, but the errors still were not gone.

It can't be moisturised filament because i have tried it with new filament and also with different material (PLA and PETG) with the same errors.

Following to that i have printed a few testprints to try and find the source of the problem (pictures in the attachements).

• Pressure advance test, with upwards rising PA value from 0,0 to 0,4 in 0,1 steps
• Pressure advance test, with upwards falling PA value from 0,4 to 0,1 in 0,1 steps
• Retraction test with a retraction length of 4mm to 7 mm (bottom to top) (i have allways used 6,5 mm)
• Retraction test with a retraction length of 0mm to 3 mm (bottom to top)
• Temperatur test with a temperatur of 220, 210, 200, 220 °C (bottom to top)
• multiple testtowers at the same time to check if the location has any effect on the issue.

Temp testtower:


Retraction testtowers:


Multiple testtowers at the same time:
I have changed the PA value from 0,3 to 0,4 and then to 0,5 and back to 0,4, then i have changed the print speed to 90% (90mm/s), 80% and 70% (changed at 10, 25, 35, 45, 55 mm). It seemed as if the speed had an effect, alltough i have printed at 100 mm/s before as my optimum, but it later turned out to have no significant effect.
What i found verry strange about this test was that some of the errors occured at the same heigth and if it would be a kartesian printer i would obviously be caused by the z-axis, but i am using a delta printer o.O...



So i am out of ideas and i hope that someone here ist able to help me with this issue. I am happy about every helpfull guess!

Best wishes
Snakergy

Could a defective stepper driver cause this kind of issues? Could you try switching for example the X driver with the E driver?

Do you have a cooling fan on the stepper drivers? Can it be this fan is damaged somehow and intermittently cooling causing the E driver to overheat sometimes causing the extruder motor to stop sometimes? I don't know what else it could be given the info. Drivers is the only part I'm missing in your story.

Did you check your E-steps/mm and could they have somehow been altered when uploading new firmware? The problem is that it looks like an intermittent issue, I think steps/mm should cause a consistent issue. Anyway, worth a check.

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http://www.marinusdebeer.nl/

Actually my cooling fan is cooling kind of intermittently, but i thought it was beacause of some weird setting i may have made in my slicer.
As soon as i am home i will change the fan and check if another fan is working any different!

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snakergy
Actually my cooling fan is cooling kind of intermittently, but i thought it was beacause of some weird setting i may have made in my slicer.
As soon as i am home i will change the fan and check if another fan is working any different!

I mean the cooling fan that cools down the stepper drivers/controller so not the part cooling fan.

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http://www.marinusdebeer.nl/

This may be a silly suggestion - feel free to ignore it - but I have been caught out in the past with a delta, when one or two of the toothed pulley fastening screws worked loose on the motor shafts. Not enough to fall off or stop rotating, but enough to allow a few degrees of rotation, depending on where the flat of the shaft was in relation to the pull on the drive belt. This was a headache to find!

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Ohmarinus

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snakergy
Actually my cooling fan is cooling kind of intermittently, but i thought it was beacause of some weird setting i may have made in my slicer.
As soon as i am home i will change the fan and check if another fan is working any different!

I mean the cooling fan that cools down the stepper drivers/controller so not the part cooling fan.

So i have checked my stepper drivers for overheating and they are not even getting hot. Anyhow i have printed with an extra cooling fan to cool down the whole board (the Duet 2 Wifi does not have a fan on its own), but it did not change anything regarding the issue.

I will try to switch the X and the E driver next, hopefully this will show some results. Should the then defect X driver result in a strangely intermittent movement of one of the towers? I will try this on the weekend!

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David J
This may be a silly suggestion - feel free to ignore it - but I have been caught out in the past with a delta, when one or two of the toothed pulley fastening screws worked loose on the motor shafts. Not enough to fall off or stop rotating, but enough to allow a few degrees of rotation, depending on where the flat of the shaft was in relation to the pull on the drive belt. This was a headache to find!

Not a silly suggestion at all, but sadly all the screws are tight :/ Checking for loose movement in the pulleys and adding new grease was one of my first not so succesfull moves.

Hello!!! I see the work Grease...

I will step in for a quick moment, I have used many types of grease and lube have had problems with the axis sticking using any grease thick or thin..
Find that a good machine oil works best, if my 3D Printer sits for a period of time I wipe all smooth rods and re-lube the linear bearings.
I even 3D Printed some SC8UU PLA plastic bushings, do not laugh they worked for medium sized prints.
When I started a long hard fast print the SC8UU PLA plastic bushings show signs of heating and sticking in various locations.

I returned to the original SC8UU linear bearings. And light machine oil. This is my personal experiences with lubricating my linear bearings.

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Computer Programmer / Electronics Technician

I have seen similar but don't know the cause.
I would suggest its an extrusion issue. I don't know which way you are printing but I think you get an under extrusion after a stop or slow print point and the stringy filament does weird things.
The diagonal faults are a bit of a clue as we see that where there is nozzle oozing. oozing being the equivalent of under extrusion.
No idea why it only does it on certain sides. May be due to the local air flow. Acceleration settings may also be an influence.

What kind of hot end does this printer use? I was looking at the manual and it appears to be an MK8 style. The manual suggests a limit of 260C, so I'm guessing it is a PTFE lined heat break? If PTFE, what is the condition of it? The manual also suggests printing speeds of 60mm/s with travel of 80mm/s, so it may be worth limiting your speed for testing purposes. The large z seams may be caused by back pressure in your bowden tube (acting as a spring), which may be mitigated by retracting on layer change and coasting. These are just my thoughts, trying to brainstorm a fix--hope to help or give ideas.
-JEB

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MCcarman
I have seen similar but don't know the cause.
I would suggest its an extrusion issue. I don't know which way you are printing but I think you get an under extrusion after a stop or slow print point and the stringy filament does weird things.
The diagonal faults are a bit of a clue as we see that where there is nozzle oozing. oozing being the equivalent of under extrusion.
No idea why it only does it on certain sides. May be due to the local air flow. Acceleration settings may also be an influence.

Yes you are right it ist underextrusion but isn't oozing the opposite of underextrusion? In my opinion it ist strang that they appear at the same time!

The airflow shouldn't be a problem, i did not change anything considering the airflow or the environment of the printer and it was working fine before.

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jefbed
What kind of hot end does this printer use? I was looking at the manual and it appears to be an MK8 style. The manual suggests a limit of 260C, so I'm guessing it is a PTFE lined heat break? If PTFE, what is the condition of it? The manual also suggests printing speeds of 60mm/s with travel of 80mm/s, so it may be worth limiting your speed for testing purposes. The large z seams may be caused by back pressure in your bowden tube (acting as a spring), which may be mitigated by retracting on layer change and coasting. These are just my thoughts, trying to brainstorm a fix--hope to help or give ideas.
-JEB

Yes i am using the original end effector. The PTFE tube is in a good condition, i have changed the nozzle and checked the Bowden tube and i have performed a cold pull (everything was clean).
Many of my testprints where at 60 mm/s with bad results. Before the issue occured i was printing at 100 mm/s without problems.
I wanted to fight the large z-seam with presure advance, but then the problems started to occure. In the back of my head i am thinking that i did not acutally turn off the pressure advance, i have used M572 D0 S0.0 to run it off.
I do not use coasting, never neede it before.

Ok so month later i have finally fixed my problems!

to make it short changing to the prusa slicer instead of cura and fixing a lot on my hotend did the Job.

I have wrtitten a more detailled conclusion in the Duet Forum for those who are interessted.

Thank you alot for your help!

Stay healthy
Snakergy