P1S
.4mm nozzle
.2mm layer height
PETG-HF (though I’ve had a similar issue with TPU)
Generic stock settings.
I’m not sure how to describe my issue besides it seems like the filament is not extruding nearly enough.
I printed with Bambu PETG translucent a few weeks ago with zero issues. Since then, I got my hands on some brand new PETG-HF for a work project and they just wont extrude properly. To the point that I can’t even run calibration prints. (Even tried with the petg translucent again and same issue)
The initial purge line just has a few dabs on it.
I am pretty confident it has nothing to do with bed adhesion (or even cleanliness).
I did run temp towers, though they didn’t look great.
Attempted to run calibration prints and couldn’t even get the results.
This printer has pulled off absolutely flawless prints in PLA (of any brand). Even after the PETG-HF failures, I ended up making the piece in PLA and it came out great!
I have recently updated both the printer and Studio. And of course set my filament to Bambu PETG-HF. Are there other settings I need to change???
Again, have already printed a few small things in PETG Translucent with zero issues. So what happened?
Are you printing on the High Temp/Smooth PEI plate?
First I would clean the plate. Your plate looks like it has a large build up of what looks like glue? Dish soap and hot water. It needs to be squeaky clean. There should be no reflectiveness of the plate.
Make sure you have the right plate selected when you slice your file. The P series doesn’t have the plate detection safeguard like the X series. It’s easy to have the wrong plate selected when slicing.
I generally do clean the plate pretty often. I’ve printed a lot with clean plates and dirty plates, but by dirty I mean its generally just Bambu glue.
I did go back and recheck I had the correct plate selected.
I’ll certainly try again with a clean plate.
I did dry it before use. Probably 50 deg. C for 6-8 hours.
I did a lot of reading before hand to determine if brand new PETG needed to be dried, and naturally I came up with the two very opposite answers. So I decided to dry it anyways as I figured it couldn’t hurt.
According to Bambu’s filament guide HERE, their PETG-HF requires drying at a temperature of 65C for 8 hours in a “blast drying oven”, which I understand to mean a laboratory grade convection oven. Using a consumer grade filament dryer at a lower temperature might require a much, MUCH longer drying time, like say 24 to 48 hours minimum.
Okay, I dried it for 12 hours overnight (my dryer only goes up to 50C.)
Seems to be working much better. Purge line still looks very under extruded, as does first layer and top layer (see last two pictures).
Same here, ran Kingroon PETG roll in Sunlu dryer for 16 hours straight @55C, but seem it did nothing to the roll, still get bursted bubble here and there on the top surface just like before hitting the dryer. I wish I could crank the temperature all the way to 11 like how I dry ABS in the airfry oven @80C.
The physic of drying filament is hot air can take more moisture than cold air, so that it would take moisture from filament. But if the air already saturated with moisture already, then moisture won’t leave the plastic to join the party with air since it’s already crowded.
PS: I got a good deal for clearance of a warehouse, AU$8 for a PETG roll. Very tempting. Sydney summer is coming and hopefully drying PETG is easier. I might bite the bullet and hit a few tens of rolls.
Apologies for those who have seen it, but filament fresh from the manufacturer can absolutely have too high of a moisture content straight from the vacuum bag with a desiccant pack.
PETG HF tends to have a higher “dryable” moisture content in my experience than PLA because PETG HF is more hygroscopic. I haven’t dried many spools of it yet but that’s how it has been going.
Here’s two photos - PETG HF straight from the bag and into the printer shows a doughy surface texture, lifting corners, and mild stringing and eruptions that cause other surface defects.
The second photo is the same spool after drying and losing about 3g of water IIRC. Flat and smooth surfaces, and no lifting. The “wet” filament was good enough maybe if I didn’t mind the defects, but without question, drying it well made it print like all the hype around PETG HF said it would. Drying is the only difference between the wet and dry images. Same model. Same plate.
Thanks for the replies!
So its been in and out of the dryer now for quite some time. Totaling well over 24 hours now. The last 14 hours was at 70C.
Tried to run some more calibration this morning and got this…
If you are going to be doing a lot of filament types and are fighting filament moisture, if you use an aquarium pump to blow a low flow of air through a desiccant column, and plumb that into a standard consumer filament dryer (I use a Sunlu S2), you can dry filament much more effectively and to arbitrarily low moisture content. Here’s a hygrometer in a plastic bag getting flow from my air dryer that I feed into my filament dryer with the desiccant column about half used. Note that the hygrometer will likely have some error, but the ones I have that can’t go this low all peg at 10% RH. Pretty certain the number is in the ballpark.
There is a floor to how dry you can dry filament in ambient air. You’ll never get lower than the RH value of taking ambient air with its humidity and heating it to whatever temperature in a filament dryer. But if you dry the air before going into the dryer, you help flow the moist air out and replace it with dry air. You remove the limit and can theoretically dry to whatever filament moisture content results in an RH of the dry air raised to filament dryer temperature.
It’s diminishing returns, though. As filament dries out, its affinity for water actually goes up which makes the last water harder to remove than the first. That drags out drying. So does mixing volume in a filament dryer and if there is a fan stirring things up. Also, filament dries from the outside. Water trapped within has to get to the surface to finally leave. These things mean the rate water leaves goes down throughout the dry but with dry air, you dry filament faster and more thoroughly than with ambient air.
Added - Using dry air to dry filament really works and works well. I stop PETG HF drying when my filament dryer hits 19-20% RH in the chamber and have started taking PLA to 20-24% since it’s not as sensitive it seems. My dried filament dries my AMS units. I put it in sealed poly boxes for storage and it pulls the RH to below 10% RH and leaves all those hygrometers pegged at 10%. I don’t have water problems any more. Not all prints are perfect but any issues are something else.
I have gotten a lot of “nozzle clog” and “wet filament”. I have done everything I can to both dry the filament, and ensure there is no clog.
I still have not gotten the PETG-HF to calibrate, but I did print some cubes and another piece and they came out “okay”.
I have now moved onto TPU (which I have previously done on this printer with zero issues) and can’t calibrate that either. Extreme under-extruding it seems.
I feel very defeated all of the sudden with this printer.
I think at this point I’d give some serious thought to just swapping out the hotend to see if that changes anything. You’ve mentioned a couple of times that your printer seems to be under extruding, which to me might suggest something could be partially clogging the nozzle. After that, I’d be looking at the extruder.
Sorry if you’ve already done that and I missed it.
