My first PET-G Carbon print - setting suggestions please.

CHANGE3D GmbH

Hi Paul

Is it possible that your retractsettings are not right? Try a higher retract distanc to see if these blobs disappear.
I am printing a lot with colorfabbs XT-CF20 and don't have such imperfections. The right flowrate is also crucial for printing with carbon fiber materials. There has to be a slight overflow but not so much that it is visibel.
Here is one of my results with carbon filament:

Best,
Markus

EDIT: I have a extrusion multiplier of 1.2 and a retract length of 0.8mm with a E3D hotend.

PaulHew

Thanks @CHANGE3D-GmbH , I will try that tomorrow.
They look really good.
I did configure the flowrate, learnt the hardway with that one!

Running 240 on hot end and a 60 bed. 45mm/s print speed.

I will check it all again tomorrow.

Thank you.

EDIT: I have an Titan Aero and V6 hotend, i just changed it from 0.8 to 0.9 and I have just started a print.
My flowrate is 71.75% Flowrate compensation is 100%

CHANGE3D GmbH

Your welcom.

Yes a clogged nozzle with carbon filament = irreversible destroyed nozzle...

I don't know what filament brand you are using but I am printing with 245°C/75°C and print with the same printing speed as PLA.
It is importand that you have a hardend nozzle on your hoten!!

PaulHew

@CHANGE3D-GmbH , Yes hardened nozzle, Technology Outlet PET-G Carbon-T filament.

Phaedrux

I think it's looking quite good, considering how sticky CF PETG is.

You might be able to eliminate those little blobs by playing with the Z seam positioning setting. The combing settings may help keep the nozzle from traversing across perimeters.

Also, if you're using Cura for retraction, you may get some benefit from the wipe settings.

It may also help playing a bit with Pressure Advance. On my Titan Aero I find a retraction distance of 0.8 to 0.9mm and PA value of 0.03 to 0.04 works well.

PETG temps can range a bit. Try +-10 degrees in either direction and see if that improves things.

And it never hurts to try drying the filament.

Final thought, in addition to the flow rate, you can try experimenting with extrusion width. Typically I find that extrusion width = to nozzle width works best most of the time, but for things like solid infill or perimeters you may get better results increasing it slightly. I think it comes down to the nozzle geometry and whether the nozzle tip has a large flat area around the orifice or if it's more pointy.

PaulHew

Appreciate the input @Phaedrux .
Where is pressure advance configured please. Cura or Duet?

I looked for linear advance in Cura after googling.
Knowing me after my post in the Ender-3, I am probably blind......!

Scachi

@paulhew Pressure Advance, I have this configured in config.g duet :
https://duet3d.dozuki.com/Wiki/Pressure_advance
https://duet3d.dozuki.com/Wiki/Gcode#Section_M572_Set_or_report_extruder_pressure_advance

PaulHew

@scachi Thank you for the info, appreciated.

PaulHew

Is it possible to change the PA whilst it is printing?

deckingman

@paulhew said in My first PET-G Carbon print - setting suggestions please.:

Is it possible to change the PA whilst it is printing?

Yes. That's one of the advantages of RepRap firmware - one can change pretty much anything "on the fly". Speeds, accelerations, PA, firmware retraction parameters, etc etc...

Edit - If you aren't already doing so, I would advise you to use firmware retraction just for the ability to tune it "on the fly". You can always resort back to slicer generated retraction using the settings you derive from using firmware retraction (but why bother?).