I need help with tuning my Bambu PETG-CF. In this thread I have the same model printed using orca-slicer calibrated settings, as well as the stock Bambu PETG-CF presets
I went through the OrcaSlicer calibration process and did some tuning, but my print ended up quite bad! Filament was dried for 8h at 65c as recommended, resulting in a RH of about 15% in the chamber it was dried in. Placed in an AMS at 10% RH with extra drying beads.
OrcaSliced print using tuned pressure advance, flow rate, max volumetric flow settings. 0.2 standard process overhang speed 75-100% 10->30 modified as suggested in the massive PETG thread. Temp was 255, Gyroid infill 15%
Since the Bambu PETG-CF preset performed better, I now tried the same with one small change, the 75%-100% overhang 10->30 speed mod as suggested by the massive thread
It looks like your nozzle temp is too high causing oozing. Id try heating the hotend to your print temp & seeing if filament oozes out.
Ive had issues with cfpa & cfpetg purge filament not being cleaned off during nozzle wipe process. The wiper was bent out of place & not making enough contact with the nozzle. This caused the same issue you have with pieces of purge filament getting into the print. I only see this issue in the start of the print though.
Filament could still be wet. What nozzle size are you using?
Nozzle size is 0.4. Print temp is 255 and I’ve gone higher to 270 and it didn’t seem to affect the layers printed. I don’t see much oozing at 255
The wiper does seem to clear filament off fine and on the build plate corners the skirt there is a smooth line with no excess. The print seems to be suffering when it prints over that wide infill area. The bottom of the print has good quality up a few mm.
I could dry the filament again 65C 8 hours. I could also try printing from outside the AMS. But the behavior is a bit suspicious
I don’t have the Bambu Lab petg-cf filament but I do use other brands.
With PETG-CF keep your layer height @ min 0.20 with a .4 nozzle and with a .6 nozzle you can go to 0.18 layer height min and I run my petg-cf at 0.25 layer height if using a .4 nozzle.
With PLA-CF you can go down to 0.16 with a .4 nozzle.
The wall count you should do 3 or more with PETG-CF it helps for infill heat and stronger parts.
PETG-CF is happy up to 30 angle when you hit 45 angle it will start going downhill unless you have better cooling.
If you can mod your part so the rear wall overhang is 30 degrees it will come out way better
with petg-cf.
On the bottom holes you have two bridge overlapping so if you up the wall count it will change the bridge pattern. Also you can set your bridge speed to 30 mm/s and see if you get better results.
The box you are printing has some very small outer wall ledges and your retractions are being placed on these ledges so on this part you would want to paint the seams like the photos. Maybe you can even tune your retractions better.
You might try changing the cooling settings and see how your petg-cf works out and I will also change the slow printing down for layer cooling on or off depending on the part design.
As you also found out some filaments are better for the part design so sometimes you have to use a filament that will be the best one for the part design.
When I print it, the touch screen tells me to open the front door. Im printing it right now with the door all the way open & the chamber fan is still running at 100%. I think having the door closed is part of your issue.
The overhang issues make sense to me. When I slice that, its printing the overhangs at 40-60mm/sec. So I’d change the overhang speed settings to 0, 20, 20, 10 (basically replacing the 25-75 settings with 20mm/sec). And make sure the fan is set pretty aggressive (default for the Bambu filament profile). For me, that only increased the print time by 5 mins.
That may address the overhang quality and the blobbing that is popping up here and there on close layers.
To address the lower pseudo overhang and blobbing issue, I think Gyroid is causing that. Try a infill that is more supportive in density. I thought rectilinear looked good to help bridge that gaps. But you could leave it as Gyroid and just slow the printer down in that section with a modifier. I think the slicer isn’t seeing the gaps in the infill and laying plastic down as if it is a flat surface. This is causing the layers to sag and blob.
These suggestions are making a lot of sense to me. Will try printing with door closed at first and slowing down the overhang speeds to 20 as well as switching to rectilinear. I definitely noticed in most recent tests that the gyroid infill is where the blobbing starts but that could also be that the filament didn’t lay up well due to cooling and then started a gap.
Ideally I can keep the door closed because I exhaust out of the print room to the exterior and want to maintain that chamber.
I think overall I’m most surprised by how badly the PETG CF preset for their own filament has been working for me
One other trick, sink the print down to the trouble areas in the slicer, and just test print those areas alone. You can also cut up the sections in the slicer too with the cut tool. That way you only waste 40-60 grams instead of the whole print. Not sure this would be needed here though. But just something to know for the future.
Thanks everyone for your help! I have also been able to finally fix my print. It came out pretty much perfect, including the overhang, the scooped inner part, all walls, no blobbing or stringing anywhere.
My key takeaways:
0. Pay attention to where in the model the failure -starts-, then fix from there. Particularly relevant to stringy filament. In my case, everything started from the large infill section that was failing to stick…
Used rectilinear infill. I changed from gyroid (which I believe was recommended in a lot of reading I did for PETG) to rectilinear as suggested by @just4memike
Printing with door closed is OK. I do have some slight CFM exhausting out of chamber but not significant, chamber temps close to bed temp.
Overhang speed reduction, settings at 0, 20, 20, 10 as suggested by @just4memike worked great to handle the overhang in my model
Reduced chamber fan speed. My issue seemed to be with the infill sticking to itself, which I think is mostly controlled by temperature of extruded filament in contact with the preceding layer’s temp. Increasing filament temp makes the temp of the extruded filament hotter versus the temp of the preceding layer affected by cooling. In my case I think having the previous layer at a higher temp was more effective than changing the extruded filament temp.
Seam placement@3DTech helped me notice that the seam placement was at some overhang locations. I ended up choosing “back” for seam placement and it ended up choosing the corner they suggested. I’m not sure if this made a big diff but the print turned out well anyways so it seemed like a fine suggestion!
Unit test the print kudos to @just4memike again, Isolate parts of the model that you’re having issues with by using the cut/model sinking function in Bambu. This might not always work but in my case I was able to reproduce the issue in specific sections of the model printed with no bearing on the rest of the model
Do to my overhang testing today with Ocra slicer 1.6.2 I did find the overhang fan speed has a bug it will not go to 90% it will show it on the preview screen but the fan is not going up on the Bambu lab display or the printed part
This is the reason I had to bump up the max fan speed threshold to 90
Ya it’s a problem in the overhang fan speed are not kicking in so I reached out to the Orca slicer team and they are going to have me test a new beta version it has some new fan time settings you can change and they think it will solve the problem
Got say the Ocra slicer team is outstanding people
Thanks for sharing this. As far as your speed settings, did you keep them the default Bambu Studio settings or change them? If so, please share? I’ve been struggling trying to dial in Bambu’s PETG-CF.
Thanks!
Hi, when you say you used the stock profile do you mean bambu stock profile or the generic petg-cf profile? The max volumetric speeds are different, generic being less.
