Strange Blobbing on Layer Change

davidewen

@giostark @Phaedrux ,

Thanks for your help.
Changing the Z Axis speed has definitely helped.

I'm still getting a dimple at the Z-Seam, but not blobs as before.

new numbers.
M566 X1500.00 Y1500.00 Z600.00 E120.00 ; set maximum instantaneous speed changes (mm/min)

test cone (N)0.6 (L)0.36 (IF)15% (S)80 (T)250°C (F)ASA (T)9m .gcode

Phaedrux

Increase your extruder jerk.

giostark

@davidewen
On the Bondtech BMG I have settled E1200. Tie well the screw otherwise the gears will dent the wire.

Norder

@davidewen
How many mm is your retract in the slicer and at what speed does it run ?

davidewen

@Phaedrux
Sorry for the slow response. We're trying to get a big project out the door and that has been consuming time.

I've increased jerk in PrusaSlicer to the following;
X: 32
Y: 32
Z: 32
E: 20

And here are my config.g settings

M566 X1500.00 Y1500.00 Z600.00 E120.00			; set maximum instantaneous speed changes (mm/min)

M203 X12000.00 Y12000.00 Z600.00 E2100.00		; set maximum speeds (mm/min)
M201 X1500.00 Y1500.00 Z500.00 E250.00			; set accelerations (mm/s^2)

Still getting the same results.

davidewen

@Norder
PrusaSlicer Retraction settings;
Length: 0.8
Z lift: 0.4
Speed: 40
Min Travel: 2
Retract on layer: off
Min travel after retract: 2
Wipe while retracting; on
retract amount before wipe: 80%

weed2all

@davidewen try retracting a little bit more...like 0.85 or 0.90! Also reduce the retraction speed to something like 25 to 30
Jerk values are to high!

Norder

@davidewen
So far the settings look good.
If you don't have stringing or other problems with blobs or similar, then the 0.8mm retraction path is probably OK. But it can change depending on the temperature and filament and then higher values would be more suitable, which could then go up to 1.5mm.

That with the speed could reduce this gap at the Z-seam, as weed2all already wrote, 25-30 mm/s may be better values for you.

If these changes don't bring any improvements, you could enter something under "Extra length on restart". Step up there by 0.1mm.
This option of "Extra length on restart" is rarely used.

Google Translate
-- Original Text --

Soweit sehen die Einstellungen gut aus.
Wenn Du kein Stringing hast oder sonstige Probleme mit Kleckse o.ä., dann sind die 0.8mm Rückzugsweg wohl OK. Es kann sich aber je nach Temperatur und Filament ändern und dann wären höhere Werte besser geeignet die dann gerne mal bis 1.5mm gehen könnten.

Das mit der Geschwindigkeit könnte diesen Spalt an der Z-Naht verringern, wie weed2all bereits schrieb sind 25-30 mm/s gegebenenfalls bessere Werte für Dich.

Sollten diese Änderungen keine Verbesserungen bringen, dann könntest Du bei "Extralänge bei Neustart" etwas eintragen. Dort Schrittweise mit 0.1mm herangehen.
Diese Option der "Extralänge bei Neustart" wird eher selten genutzt.

Phaedrux

@davidewen said in Strange Blobbing on Layer Change:

I've increased jerk in PrusaSlicer to the following;
X: 32
Y: 32
Z: 32
E: 20

Where did you change that?

I assume that's in mm/s?

Does prusa slicer now allow per move jerk settings as well as acceleration? I didn't think so.

Is your prusa slicer set to RepRap gcode flavour?

Can you share a sliced gcode file?

Your config file still has the limits set very low, so unless your slicer is actually sending M566/M203/M201 commands to change the limits during a print you are being limited by the config.g

Norder

@Phaedrux

Does prusa slicer now allow per move jerk settings as well as acceleration? I didn't think so.

The PrusaSlicer has its own jerk setting (mm/s), maximum acceleration (mm/s²) and maximum feed (mm/s)
for each axis.

Phaedrux

@Norder said in Strange Blobbing on Layer Change:

The PrusaSlicer has its own jerk setting

Where? You mean in the machine limits?

Norder

@Phaedrux
Yes, exactly.
But it is clear that the upper limit is determined by the config.g.

davidewen

@Norder @Phaedrux @weed2all

Thank you all for responding.
I will not be able to check settings or respond back with said settings until late next week.

Cheers

davidewen

@Phaedrux

Yes, I made those changes in PrusaSlicer.
Are you suggesting that I make the changes in config.g?
And if so, is that command M566?

My current M566 is not labeled "jerk" so I just want to confirm.

M566 X1500.00 Y1500.00 Z600.00 E120.00			; set maximum instantaneous speed changes (mm/min)

M203 X12000.00 Y12000.00 Z600.00 E2100.00		; set maximum speeds (mm/min)

M201 X1500.00 Y1500.00 Z500.00 E250.00			; set accelerations (mm/s^2)

Phaedrux

Yes, maximum instantaneous speed changes is often called jerk.

davidewen

@Phaedrux

Got it. Do you have some recommendations from my current settings?

Phaedrux

@davidewen Try these

M566 X1500.00 Y1500.00 Z600.00 E3000			; set maximum instantaneous speed changes (mm/min)
 
M203 X12000.00 Y12000.00 Z600.00 E6000		; set maximum speeds (mm/min)
 
M201 X1500.00 Y1500.00 Z500.00 E3000			; set accelerations (mm/s^2)

davidewen

@Phaedrux
Thanks for the info. This has helped a lot. Seam is still there, but greatly improved.
I will play around with these settings to see if I can get it to almost perfect.

Cheers!

Phaedrux

@davidewen said in Strange Blobbing on Layer Change:

Seam is still there, but greatly improved.

Have you tune pressure advance yet? That's the remaining piece of the puzzle.

https://docs.duet3d.com/en/User_manual/Tuning/Pressure_advance