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This will help everyone to better underHi there,
I’ve got a frustrating issue with my P1S. Every time when I print something that is higher than 5mm, the infill fails due to under-extrusion. It causes bumps in my prints and weakens the structure. So the first 5 mm are fine, but then the under-extrusion starts to happen. Every single time.
I use the Bambu Slicer and use the generative PETG settings. I have the same problem in every layer height/quality. The filament I use is PETG from Azure Film. I dry and preheat my filament. I even tried a completely new dry roll out of the box. Same problem. So it can’t be wet filament, right?
The type of infill or the percentage doesn’t matter either.
When I slow down the printer to a 50% speed, the problem goes away.
What is the reason that the infill gets under-extrusion after 5mm of printing? Does anybody know (of any suggestions)?stand your problem, and provide you with the best solution.
A completely dry roll out of the box is not a thing one can count on. You can never be sure of the state of a freshly opened spool of filament. With PETG I think you will always want to dry it at the recommended first. So you should elucidate your process of drying, what dryer, what temp, how long?
The only way to be sure of the dryness is to weigh the roll first and then periodically to determine the percentage weight loss and then stop when it levels out.
Also, the slowing down helping makes me think you may have a smaller part and min layer time isn’t turned on or is too low?
With PETG I’m also generally concerned about nozzle blobbing, so make sure to get a high enough nozzle temp to keep the filament from balling up on it, imo.
A completely dry roll out of the box is not a thing one can count on.
Fair enough. If you want to know for sure, you need to test it! So this means I will have to do some more tests for a couple of days.
On the other hand; I’ve been printing with this filament for years now; first with a Ender 3 (slow speeds), then with a Creality K1 Max on high speeds and now on the P1S. The K1 Max is a good comparison and never had this problem on the K1 (although many others! )
Concerning the dryer; it is a Sunlu Filadryer S1 plus: SUNLU FilaDryer S1 Plus | 3D Prima - 3D-Printers and filaments
I heat up the machine 1 hour prior to printing to 55 degrees. and it only opens when I change the filament. I see that there’s something to win here, but I’m still in doubt if this is the root cause of the problem, as I haven’t had this issue before.
Also, the slowing down helping makes me think you may have a smaller part and min layer time isn’t turned on or is too low?
It is indeed a pretty small print, but what do you mean with min layer time? I’m unfamiliar with that function.
With PETG I’m also generally concerned about nozzle blobbing, so make sure to get a high enough nozzle temp to keep the filament from balling up on it, IMO.
I’ve cleaned the nozzle several times, but with no result. I print at 255 degrees and the bed is heated up to 70 degrees.
It is just that the first 5mm I have no issues at all, but only than and with every print, the issue starts to occur. So why is that? If it is moist filament, why doesn’t it occur in the first 20-40 layers (depending on the layer height)? The same goes for temperature and speed. It is the same on every layer, but still it starts to occur at appr. the same height.
Did the problem come along with a new roll of filament? That is the way to tell because in fact you may have great luck with filament arriving dry until it does not one day. You do make a point about the lower parts of the model, which makes me wonder… The S1 is 55C max which is not quite the 65C generally required for drying PETG, not a huge deal but it will take longer. So I can imagine the following scenario:
The one hour pre-heat gets 5mm worth of filament dry on the outside of the roll, just where you need it… What you need to do is dry it for 12 hours plus overnight and then print and i would venture to guess that the 5mm will increase.
I really think the drying is the issue due to the look of your gyroid infill, classic wet filament look, what you can do is when you stop the bad print, lower the bed and pinch off any excess filament with tweezers. Now, set the nozzle temp to whatever you are using (255C) and when it reaches that extrude some filament with the manual controls and quickly pinch it off with tweezers, does it now continue to come out of the hot end? It should not but if there is moisture it will be expanding the filament while it boils and you will get filament pushed out of the hot end.
Min layer time is a function of the filament profile, it is there to make sure if you have a very small layer it has time to set up before the next layer starts. It will usually result in a very slow print speed to make sure the layer takes seconds.
Above is the default for Bambu PETG Basic. I guess you are using the generic PETG so things will be slightly different. Note the Layer Time property, here is says that the layer should take at least 12 seconds.
No it didn’t actually. It’s the same with old and fresh filament.
I just turned on the S1 heater for tomorrow morning. I will leave it on for 12-14 hours before the next print tomorrow morning. Let’s see what happens!
I can also try this tomorrow:
It does tend to ooze out a bit when the nozzle is heated up, but let’s see what happens when I dry it overnight at 55C first.
Got it! This might help, but the infill errors are everywhere, so let’s go for drying first!
Almost forgot, I also use the S1 for PLA. I have S4 for PETG etc it’s really nice and I recommend it if you are doing a lot of printing.
But what I meant to say is when doing a dry in the S1 for a long period like overnight you should crack the lid to allow expelled moisture to escape, it is an S1 design flaw. I use a ~5mm wedge at the front of the unit from a ‘filament clip’ print, suppose a pencil would work too.
I tested 2 things today; First the preheated filament (with the closed lid). It worked better. Not good, but better. And in the end it had the same failure.
The second test involved pausing the print, heating the nozzle to 255, extruding, and cutting after extruding. It started oozing right away. To be honest, it started oozing while I was heating the nozzle in the place.
Tomorrow I will do another test after a full 24h dry with a partially opened lid.
So after more a drying period of 24h> the results are much better.
Still, when you pause the print and heat up the nozzle to 255 degrees, about 1cm of filament oozes out. Not as much as before, but still you see some oozing…
Concerning the print, there are better results. it looks like its gone.
Well, I would say make your judgement based on the final surface. A few strings here and there will happen on underlayers depending on overhang etc, but this is why we have top layer shell #layers (more or less). The final layers have to bridge the infill, the first layer of this is rarely going to look perfect but after at least 3 layers it should be mostly worked out.
You can always go to a smaller layer height or variable layer height to compensate.
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