Issues with generic PETG

[TurboManELou]

Hey all, I’m TOTALLY new to 3d printing, and the P2S is my first ever 3d printer. I first started off printing generic PLA, and everything was great, perfect.

I decided to try out some generic PETG next. I dried my rolls in the AMS 2 for over 12 hours. At the moment, I am only using makers world projects, as I have not created anything on my own. I have realized that I am having issues printing with PETG.

On my first project, I had to bump the temps down from 275 to 255 degrees to prevent blobs from building up on the nozzle. That seemed to work great. I even went as far as printing a temperature tower. Please see picture.

At the moment, I have been keeping my nozzle temps at 245-255. This seems to eliminate the blobs. I have noticed though that I am getting some pretty bad stringing on my prints. See picture below.

The print above did finish, and is not a total waste, but the extreme edges have that bad stringing. I read alot of forums that said this could be due to the part cooling fand running, which I noticed is usually running at about 90% during PETG printing. See picture below.

Based on recommendations, I kicked that back to 60% and had a total failure of my print. See picture below.

This print was actually knocked over by the print head, and tons on spaghetti was on my print bed. I had to abort the print and start over. This happened to be a multi part print, with 4 tall towers. I started over, and only selected to print 1 tower at a time, at let the part cooling fan run at its set rate of 90%. The single, individual print came out GREAT. No issues.

This is a stock print from makers world, that specified PLA, but I selected PETG from Bambu Studio, and everything came out good on the individual piece. I now have to repeat that print 3 more times. Again, I have not changed any settings permanently. I am totally lost as to what I need to do to get PETG to print. I have no issues whatsoever with bed adhesion. It almost seems like the individual part printed slower than the full plate print. Please help! If you all need any more pictures, like my settings, please let me know and I can post. Thank you!

EDIT! I am also adding some pictures of my settings for this particular filament. These are presets, and I have not changed anything with these settings. Does anything look “off”?

[Bullocks]

I would begin by drying the PETG roll. Fine stringing near seams/travels are very often from dryness problems. PETG is susceptible to moisture.

You didn’t mention the brand of petg. PETG is unlike PLA, in that the various companies formulations are sometimes very different from one another. It might help to mention what you’re using. Some love heat some do not.

The fine strings also can be nearly completely removed and cleaned up with a quick pass of a jet-style blue-flame lighter, or heat gun/soldering station air.

Re: print time, the “generic petg” profile has a minimum layer time of 12s, which means that even if you have one small item on the plate, it’ll reduce speed to hit 12s every layer. My guess is that is what you’re bumping into. The concept of speed optimization is far too long for a forum post. 3 speed params (v,a,j) multiple constraints (min time, max flow), multiple operations that take static time (wipe, spiral, timelapse, etc).

[TurboManELou]

Thank you for that insight. The brand that I am using is Sunlu PETG. This filament has been dried for over 12 hours in my AMS 2. What do you think about the speed that my presets are using? I have uploaded pictures straight from Bambu Studio.

What your saying about the 12 seconds interest me. As I said, when I had 1 item on the print bed, it looked as if it was printing slower, and all of my issues were solved. How would I go about slowing down the layer time when I have multiple items on the bed, so each items layer is slowed down? I think its a speed issue im running into.

[Bullocks]

The settings below inform the slicer what to try to do when the sliced time is less than 12s. This is very model-dependant, but I generally choose to enable “dont slow down outer walls” which helps the piece get a better consistent finish, but it means it has to slow down the inner walls/infill even more dramatically which might cause other problems.

I dont have the p2 series so don’t really want to push much advice that might not be correct. On an A1, with tinmorry brand PETG, I use much less fan (40%) around same temp (250) and I use the Max Volumetric Flow control set to a low value (6) to throttle the machine at it this “max flow” which in turn limits it’s speed without having to tune the actual mechanical speeds. 6 mm3/s volumetric flow is about equivalent to 70-80mm/s speed at normal 0.4 nozzle lines.

Dry is a perpetual problem lol. I only trust scales. Weigh, dry, weigh again. It will follow an asymptotic curve and you can stop when you only see small changes. I agree that your might be dry enough [from the temp tower result] but from the other side of the pixels it’s hard to be sure.

[TurboManELou]

Last night, I did try to turn the fan speed down to about 60%, that is when I had the catastrophic failure of the print being knocked from the plate. What im assuming happened, is that I developed a blob on the nozzle, and that struck the print which knocked it from the plate. Im not sure if lowering the fan speed had anything to do with the blob, unless my speeds were to high, not allowing the layers to fully dry and harden before moving on.

[Olias]

Welcome to the community.

Before I make any suggestions I have one question. Where did you get this model? I’m seeing it now multiple times in other forums and in most cases, people are downloading it and using it incorrectly. Not to also mention that as temperature towers go, this is very wasteful of filament and unless one is experienced, it tries to do too many things at once and doing none well. Did Bambu Studio change their Temp Calibration - I abandoned BS well over a year ago and have been on Orca Slicer ever since and that model was not part of the last version of BS and definitely is not part of Orca’s temp calibration routine.

From what I see, this tower was printed at one temperature which leads me to believe the static STL was downloaded unmodified. The baked in models or 3MF files will have the necessary GCode to vary temperature.

Here’s what a properly coded temp tower should look like when the temp gradient filter is applied. Double check to make sure you see this rainbow scheme if not, then that confirms that tower was improperly printed.

Correct tower temperature gradient

Incorrect temp gradient. Note only one temperature.

Troublshooting 101 - Change only one variable at a time

You’re on the right track, but the best word of advice I can give a newbie and the single most common error I see repeated daily is what I call thrashing. That’s when multiple troubleshooting steps attempted before verifying that they worked or did not work.

Let’s go in order.

1. Drying the filament: That’s a great first step for PETG. The pitfall is assumptions that X amount of hours at X degrees means its dry. It might be, it might not be. There is only one way to be sure. Weigh the filament before drying and weigh it during drying. Only when it stops losing weight can you be sure there is no moisture. That assumes that the filament was in a dryer of oven over 50 C. PETG is best heated to 60 - 65 C. If it never loses weight, then congratulations, it was dry to begin with.

2. Temp calibration and Build plate Hygeine. I commented already above on temp, s I won’t repeat it here but one comment that I want to dive into:

@TurboManELou

I had to bump the temps down from 275 to 255 degrees to prevent blobs from building up on the nozzle.

Where did these blobs occur exactly? Did they appear at the point in which the nozzle made contact with the plate? If so, that’s a first layer adhesion issue and washing the plate should be the first step.

3. PA Calibration and flowrate calibration. I am not too troubled by this image but it should be investigated. Stringing like this is most often associated with either improper temp, PA calibration or improper retraction.
   
   

• For temp - you already know what you have to do, mentioned already above.
• Pressure Advance - There is PA Calibration utility baked into Orca or you likely will find it as a downloadable 3MF file. Bambu Studio may have it by now but as I have not been using BS since v1.6, I wouldn’t be able to guide you, perhaps someone else can comment.
• Retraction - This can be tested using any string torture test. There is a retraction test in Orca Slicer - If you haven’t pick up on the vibe yet, Get Orca Slicer. home · OrcaSlicer/OrcaSlicer Wiki · GitHub
  
  
  
  
  

4. Layer adhesion mid-print,

• Does this happen at the same point in each print.
• Here is what I am seeing. The filament is either cooling to fast (fan issue), is not flowing correctly, or is not hot enough when it makes contact with the next layer.
  
  
• Check your fan setting in the filament profile and try turning it off and see what results occur if any.
  
  
• Also make sure your chamber temps are warm, above 35C should be good enough. You may have to heat up the build plate and wait for the chamber to heat soak. 15-30 minutes should do it but I prefer to keep two thermometers in the chamber, one at the bottom and another at the height of the home position of the build plate but adhered to the wall so it does not touch the wall or the plate.

Most of all; Change only ONE variable at a time and note your results before moving onto the next test.

Good luck!!!

[TurboManELou]

Thank you for that reply, ill try to answer your questions as thoroughly as possible!

1. The temp tower I downloaded from Makers World. I did verify that the temps were actually changing, as in the slicer I had the “rainbow” effect, and I witnessed the nozzle temps changing as the print progressed. I checked that the G Code had the correct temperature changes
2. I have never weighed the filament, but my AMS shows a pretty steady temperature of 65 C during the drying time.
3. I can assure you that my plate was clean. I only use dish soap and warm water.
4. These blobs usually occur anywhere after the first 20 to 30 layers. Bed adhesion is great, no issues there. its when the print is in full force that these blobs happen, and they only happened when my nozzle temps are set to 255 C or above. Dropping the temps down usually gets rid of the blobs.
5. I am in agreement with the cooling to fast statement that you made. As I stated, my part fan stays on 90% for the duration of the print. Isn’t that to high of a fan speed? Wont this cool down my print way to fast? I’m thinking that its not happening on the first layers because the bed temp of 70 C is keeping those layers warm, and not allowing them to cool as quickly.
6. Chamber temps are steady at 37-40 C normally.

Are you suggesting turning the fans completely off? Should I adjust the speed also?

[Olias]

Thanks for adding clarification.

I think in bullet #5, Fan speeds. You may have found your smoking gun. Fans should not be on in PETG under most circumstances. This would also be consistent with the failure mode you showed in your photos. It’s an easy thing to test too.

One quick thing you can try. Try to print with the Bambu PETG basic profile and test the results. From there you can fine tune the fan speeds.

Or simply compare the two profiles in the slicer. Here’s where to navigate to the comparison table in case you haven’t used that option before.

[RocketSled]

If you’ve tuned temperature and flow and PA and dried it, and you’re still getting stringing, you may be moving too fast. Exceeding the flow rate of the filament. Slow down the print speed, see if that has an effect.

[lkraus]

@Olias

There is PA Calibration utility baked into Orca or you likely will find it as a downloadable 3MF file. Bambu Studio may have it by now but as I have not been using BS since v1.6, I wouldn’t be able to guide you, perhaps someone else can comment.

FWIW, Studio has borrowed some of the OrcaSlicer calibrations. “Develop mode” must be enabled in Preferences to show the dropdown on the top line:

[TurboManELou]

Thank you all so much for your support and help. I have enabled developer mode, and will run some test! I have a few more questions:

1. For the test I will be running, im assuming I need to run these test with the PETG filament that I normally print with, and select the Generic PETG profile that I have been using?
2. How exactly do I “slow down” my print? If the speed is the only thing I need to worry about, how do I go about “slowing down”? Do I need to create a whole new filament profile?
3. How do I adjust the fan speed and make it hold, and not revert back to a preset number?

Thank you again for bearing with me, as I’m totally new to this. These questions may seem dumb to some of you, but this is the level that im currently at!

[blchandl2]

One more question for the OP. What infill patterns are you using? With PETG, I try to avoid any infill patterns that cross themselves. PETG is gooey and it adds to the material buildup on the nozzle and drags it everywhere. Gyroid is a good choice for PETG.

[TurboManELou]

I honestly have no idea what infill pattern is being used. I literally found the print on makers world and imported it into Bambu Studio, changed the filament from PLA to PTEG and hit go! Im sorry I couldn’t be of more help for your question.

On another note, I just printed an individual item, from the larger project that I started last night. I imported the large project, which is labeled as PLA, removed all but one part from the print plate, and it printed flawlessly. I didn’t change any settings at all, other than setting nozzle temp to 250 C. The print did seem to go slower than the full plate did that failed. But it came out great, even with the part fan at 90% the entire time. I’m so confused now! The only thing that seemed to be different other than the size of my project was the speed of the print, which I did not even adjust.

[user_254122797]

I worked in IT 30+ years. Remember the KISS method. Keep It Simple Stupid

[Olias]

@user_254122797

I worked in IT 30+ years. Remember the KISS method.

Was that intended as advice? I may have lost the nuance.

[blchandl2]

For some reason that menu does not appear for me. I have the latest version of BS and Develop Mode enabled. I only get PA and FR calibrations. Is that because I have a P1S?

[lkraus]

Calibration is in two spots with Develop mode enabled, you want the other one.

[user_254122797]

Yes.Only change one thing at a time.If you change a bunch of stuff you want know what solved your problem

[Olias]

@user_254122797

Only change one thing at a time

I’m still unclear on your post.

Were you referring to this?:

[blchandl2]

Nope, just the two basic calibrations available.