Hi,
I am experiencing some issues when printing PETG and I am really running out of ideas. My biggest problem is that the prints always have blobs/clumping especially on the sides of the objects as well as “holes” in the wall. For the infill I always use non crossing patterns.
The problems are extreme when printing with eSun PETG…
calibrated the filaments in Orca (including PA, Flowrate, Temp.)
decreased the speed (values are even under the recommendations of eSun)
decreased the max. flow rate
adjusted the retract
disabled z-hop
increased travel speed (to reduce time were blobs or clumps can arise)
changed cooling parameters
But I am still not really sure about the correct cooling-settings since there a different opinions here in the forum. Some say the Aux fan needs to be higher than the part fan and some say the opposite. So maybe you have an answer for that as well.
As an additional information: I am using a hotend/cht nozzle (hardened) from Ali as well as a heater/thermistor unit from Ali. I checked the correctness of the temp. using my Voltcraft 204 Datalogger. At 150°C it is about 3°C off the stated temperature on the display. At 250°C about 8-9°C off and at 300°C about 15-18°C off.
I don’t know if that is a lot, but I can imagine that the temperature climbs a bit when the silicone sock is installed.
I measured underneath the clip that holds the heater in place. I applied some thermal grease to get more precise results.
I hope someone has an idea or can share me a properly workin profile for either eSun or Jayo PETG.
I print loads of Esun PETG it’s hard to setup but does print good. You want to drop your flow ratio down it’s way to high bring it down to 0.947 and also your pressure advance wants to be closer to 0.015-0.017. Also your volumetric speed wants to be halved to 10mm3. Set your part cooling to minimum 10% maximum of 45% overhangs around 50-75% and print at between 70-120mm, I prefer to hover around 70-80mm. The filament also doesn’t play nice with to much retraction.
I shared my settings in the my most satisfying filament post, link below the settings are near the bottom and a sample photo of a print in Esun white PETG is a few above it. Or if you want the easier option look me up on MakerWorld, same name as here. Most my stuff is Esun PETG solid white I love it
Nice to see a truly well documented and methodic way of problem solving… and sad to see that it hasn’t alleviated you issues.
This leads me to think about that AliExpress heater-thermistor and “CHT” nozzle you have. I write “CHT” in quotes, as I kind of assume that it’s also from AliExpress, and if that’s the case, all they did was to make the split in strands from one to three to one - but the machining is nowhere near Bondtech’s, which shows in flow tests. The AliExpress knock-offs lack the chamfer that the original has. That in itself doesn’t cause PETG to misbehave, but maybe the material they made the nozzle of, can be cause for concern.
I’ve had nozzles whose surface treatment like to make certain filaments stick more, causing them to string more.
You nozzle diameter could also be a bit imprecise.
So; do you have an original, working, Bambu Lab complete hotend that you can try? This could help see where the problem may be.
Thank you very much for your advice. I changed the settings as stated in your post. It worked much better, no more holes (except one where I paused the print, but that’s my fault) and the blobs are nearly gone. Also it now has more the look of the Jayo or Petg in general. Way more glossy than before.
Although your settings seem to be very good, I still can see that the nozzle “collects” quite a bit of material. A big amount in comparison to other filaments like PLA. I know that this is kind of characteristic for Petg but I am curious how you handled it or maybe even got completely rid of it.
Actually I have only the two nozzles that came with the printer but no stock thermistor/heater unit because a cable of mine became loose after 3 months causing a loose contact. I fixed it by soldering it but it didn’t last too long. But I will go order one tomorrow, because I think switching to the stock hotend assembly isn’t a bad idea - especially because I don’t really care about high flow rates anymore.
While I wait I will definitely give the stock one a chance again, even with the Ali heater/thermistor (it has worked fine for over 300h now) it could make a difference.
Indeed my whole hotend assembly (except the fan) is from Ali and I can imagine that the fabrication of the parts aren’t as good as others, I mean there’s a heavy difference in terms of pricing and you have to make compromises somewhere.
I thought about buying a Bigtreetech Panda Revo hotend or the one that Slice Engineering just released - What do you think of them?
No worries, yes petg is very stick and oozy, you need to clean the nozzle with a wire brush regularly while it’s warm to keep the buildup down, I recommend a brass one rather than steel.
You can play with the flow ratio to improve it try taking 0.002-0.005 off and see how it goes, if the print is still good but you still have lots of oozing try a little more. This will drop the extrusion level a bit sometimes it’s better to under extruded with PETG depending on the print. I need to under extrude a little when printing larger prints like cylinders and boxes.
Sometimes you will just need to settle with a bit of build up and brush the nozzle off after each print.
I have only information about what I’ve read. The Panda Revo gets great reviews - as do the (pricey) E3D obXidian. Personally, I’ll probably choose a 0.6mm obXidian - because higher flow rates makes more sense with 0.6 and 0.8mm nozzles, in my opinion - at least for the type of printing I mainly do. To utilize a flowrate of, say, 30-35 mm3/s with a 0.4mm nozzle, very high speeds and accelerations are required, and quality would suffer from other reasons than flow-related.
Thank you @oddsandsods@jakobdam. Both your tips have helped me to get lovely and very clean looking PETG prints.
It seemed like adjusting the speed, reducing volumetric speed and the PA helped me to get better overall results and since I switched to the original Bambu hotend/nozzle I have no more blobs/clumping.
This was the first print to have perfect quality, so once again: Thank you very much
