PETG Filament build up around the Nozzle  

RE:

I've noticed similar issues with my XL. Prints perfectly with PLA but PETG seems to result in the nozzle slightly dragging in the first layer and accumulating filament. Not much but enough to have to clean the nozzle between prints to avoid clumps of filament dropping on the subsequent prints.

There's a filament override section in Prusaslicer under Filament Settings but it only affects retraction.

You could theoretically use the Z-offset parameter in Printer Settings>>General>>Size and coordinates, but that's not filament specific so you'd have to create a new printer profile just for PETG, and at least for me with several physical printers and nozzle sizes configured, this would make my printer menu explode.

Curious what others say.

RE: PETG Filament build up around the Nozzle

After reprinting I found at least the error for the massive build up. One part lost adhesion, got stuck on the nozzle and I stopped it. First time it happened it must have caused a layer shift and the hotend got covered in Filament.

But still, the curling PETG around the nozzle and the blobs that accumulate, fall of and lay around are still a little mystery. Flow is calibrated, it may be even slightly lower than it should (if you trust the two wall cube). I’ll test some more, reduced parts on the sheet and used some hairspray. PETG can be a pain in the a**.

RE: PETG Filament build up around the Nozzle

Posted by: @mcbeary

After reprinting I found at least the error for the massive build up. One part lost adhesion, got stuck on the nozzle and I stopped it. First time it happened it must have caused a layer shift and the hotend got covered in Filament.

But still, the curling PETG around the nozzle and the blobs that accumulate, fall of and lay around are still a little mystery. Flow is calibrated, it may be even slightly lower than it should (if you trust the two wall cube). I’ll test some more, reduced parts on the sheet and used some hairspray. PETG can be a pain in the a**.

PETG is notorious for blobbing and accumulating, it can be tricky to find the right mix of settings to mitigate it.  I've started printing in ASA a lot of times when I would have used PETG in the past.  Not always possible based on the need of the part, but in many cases.

RE: PETG Filament build up around the Nozzle

Sure. But I was under the assumption of out of the box printing. I’ll tune some more then 🤗

RE:

Yes, we all know that PETG can be a nasty customer more often than not.

Which brand of PETg and plate are you printing with ? (smooth, textured, satin.. ). Are you positive that the filament is perfectly dry ?. If you’re unsure, dry it. Don’t print very fast (specially infills ) and try lowering a few degrees the nozzle temperature, I see that you started using adhesive; that can help and it’s quasi mandatory on the smooth sheet.  Time ago I purchased a flask of plastic repellent paint and I apply it regularly on the nozzle. It doesn’t makes wonders, but helps a bit.

Anyway, depending on the brand, results can differ a lot. After trying several of them, nowadays my PETG of choice is Geeetech. I prefer it to Prusament, which tends to be more stringy and sticky, at least with my setup.

RE: PETG Filament build up around the Nozzle

Posted by: @artur5

Yes, we all know that PETG can be a nasty customer more often than not.

Which brand of PETg and plate are you printing with ? (smooth, textured, satin.. ). Are you positive that the filament is perfectly dry ?. If you’re unsure, dry it. Don’t print very fast (specially infills ) and try lowering a few degrees the nozzle temperature, I see that you started using adhesive; that can help and it’s quasi mandatory on the smooth sheet.  Time ago I purchased a flask of plastic repellent paint and I apply it regularly on the nozzle. It doesn’t makes wonders, but helps a bit.

Anyway, depending on the brand, results can differ a lot. After trying several of them, nowadays my PETG of choice is Geeetech. I prefer it to Prusament, which tends to be more stringy and sticky, at least with my setup.

Agree with all of the above.  I find Polymaker also works really well for printability, adhesion, layering, and finish.

RE: PETG Filament build up around the Nozzle

I use Filament PM. As far as I know, they do produce for Prusa. In this case, this one was the former Prusa Orange from 2018, although it’s more red.

After starting with PLA in the Mk4 (I mostly print PETG though), I switched to the textured sheet for PETG.

You maybe right regarding the speed, I didn’t change that in the PrusaSlicer, just the brand of filament. The roll used should be dry, I just opened it up. Speed maybe an issue, I’ll try and test print something at different speeds. 

Then problem bothering me is, I had this a long time ago on my Ender and solved it, but forgot how. I always had some slow build up and every now and than a small blob with a string fell of, slightly burned after being attached to the hotend for a while.

Thanks for the advice 👍🏻

RE: PETG Filament build up around the Nozzle

I can confirm that at least some of the Prusa branded filaments (non-Prusament) are the same as FilamentPM.  In particular, that silver-gray that used to be sent with each new printer is of FilamentPM origin.

My experience with PETg is that it is most definitely more oozy than PLA or ABS.  I've also observed that PETg does not produce as fine details as those two.

I've found that increasing the infill percentage on larger flat PETg pieces can indeed cause blobbing and accumulation on the nozzle.

RE: PETG Filament build up around the Nozzle

Interesting, I didn’t know, that ABS is better in details and less oozy as PETG. Unfortunately I don’t have the printer housed or in a place, where I can safely print ABS. But I’ll give it a try, once that changes.

And I got a Lotte update, maybe not scientific yet. I printed with the newest Alpha version of Prusa Slicer and the last stable one was less stringy. Before that, I increased the retraction to 1.2mm. The temp tower I printed looked good at 235, the print after had more strings as usual and a few burned blobs.With the stable version and more different objects, so a lot of travel between, almost no strings and just one small burned blob. So, it maybe this could be an issue too.

RE: PETG Filament build up around the Nozzle

I say that because when I started printing small gears for some mechanical projects, mostly model railroad related, I tried the gears in various filaments to see which ones worked better.

PLA worked the best for smaller-tooth gears, with ABS almost as good.

PETg not only gave poorer resolution on the smaller gear teeth, but it was noticeably softer than the other two.

I suspect that PC Blend might be even better, but the PLA gears do what I want.

I've found that ABS, for some reason, does a very nice job for some detailed pieces, such as fire escape stairs and railings for model railroad buildings.

If you want to print ABS without an enclosure, you can use the draft shield option to make a mini-enclosure around your print.  I did that before I got the enclosure and it does work well, particularly with smaller prints.

RE: PETG Filament build up around the Nozzle

The problem I have with ABS is only the „toxic“ fumes. We don’t have much space, so I don’t have an extra room to print in at the moment.

But nevertheless, interesting what your experience is with it.

RE: PETG Filament build up around the Nozzle

I too had problems with this. Reading about several sources suggest a higher Z for the first layer. One source Sait 0.1mm about the thickness of two pieces of printing paper. So here is a caveman solution:

What if you place two pieces of paper under the nozzle during bed leveling before the print starts? I'm gonna try this with my next long-ish print.

RE: PETG Filament build up around the Nozzle

I'm getting a lot of build up around the nozzle too during printing with PETG on the XL. When I'm printing one color, it seems to build upon the first few layers. It comes off in the print usually, and the nozzle then doesn't have a huge mound of it on it any more. Seems to then print without building up quite so much. But I'm definitely seeing it come off in the print, which is disappointing.

I did the brass brush mod for the tool changers as well as the nozzle cleaning on the brass brushes before the print starts the first layer calibration (models found on Printables). This helps clean up any ooze before calibration but doesn't help during the print.

I run the filament from a filament drier during printing, and I run it a little bit each day on a scheduled timer to keep it dry inside. So it should be plenty dry. I found drying the filament really improved stringing on my MK3S so I run the drier when printing now.

I'm using the same filament (Overture PETG) that I've used for a few years with my MK3S. Printing PETG on the MK3S would require only removing a tiny bit of material from the end of the print nozzle after the print finished and cooled down. I never had buildup around the nozzle where I had to clean it with a brass brush.

With the XL, like others have said, I have to clean it before each print during the nozzle/bed warmup stage. But it builds back up again quickly.

With my MK3S, I'd clean the nozzle off cold, click Print, and walk away and come back when it was finished. Didn't have to think about it at all and it printed flawlessly. The XL I have to clean and monitor more, especially during the first few layers with large prints with lots of movements (large gridfinity bases) to make sure nothing gets messy.

If anyone finds a way to prevent this PETG buildup, I'd be very interested as I print almost entirely in PETG for functional parts.