[Solved] Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)  

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

[Arg.. there is a edit topic timeout, but I wasn't finished writing the topic]

- I tried cleaning the sheets with Isopropyl alcohol, and carefully removing any dust particle

- I tried cleaning underneath the sheet

- I only tested printing the object with the large base plate on PETG, I am not sure if this is a material issue

- I tried re-calibrating the axis

I am pretty new to 3d printing, so I might do something wrong here. But currently I am out of ideas. So thanks for any help.

RE:

 I think that the words “recycled Prusament PETG” are key to this issue. PETG is infamous for sticking to the nozzle instead of the bed, although some of them are worse. During the last years I used several brands of PETG. For order of preference : Geeetch ( my favorite ) Polymaker and Prusament ( bottom of the list ). More to the point, I printed three Prusament PETG colors : black, neon green and terracotta. All are very sensitive to moisture and require higher nozzle temperature than other brands. While jet black is OK, terracotta is very finicky, Apart from sticking to the tip of the nozzle, it manages to mess the infill, even rectilinear or gyroid, and you have to print very, very slowly. Although I like that color a lot, this filament is a PITA to use for large parts.

I never tried recycled Prusament PETG but I wouldn’t be surprised if it’s even worse in this regard. To mitigate the problem, the filament must be perfectly dry. As said many times in this forum, a new sealed spool isn’t a guarantee of dry filament,  How did you try to dehydrate it ?. Ideally the spool should be dried in a filament drier or food dehydrator for at least five-six hours at 60-65C. Being a recycled material, I’m not sure that this will fix totally the nozzle sticking issue, but surely it will improve somehow.

Apart from that, some nozzle materials seem to attract PETG more than others. Be sure that the nozzle is perfectly clean and free from filament residues. Applying a coat of anti-adherent paint to the tip helps a bit as well.  

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

Hot water and dish soap to clean for PETG, not alcohol. Consider a scotch-brite for cleaning as well.

Other rhan being dry, the tiniest lift will cause this. You may also need to tweak extrusion muktiplier (flow if live tuning)

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

I dried it in a standard convection oven, with a temperature probe, for about 6h at 55-60 degree Celsius, I can try repeating that.

I used the default and CHT brass 0.4 mm prusa nextruder nuzzles, but I also have obxidian nozzles, would they be better? Or maybe bigger diameters?

I will look into anti-adherent paint, thx for the tip.

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

Have you tried reducing the temperature by taking the lowest value plus 5° from the filament manufacturer (Example: 230°-250°, choose 235° and increase the bed temperature by 5° (if 80 go to 85°) these settings work for me.

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

Posted by: @cjd

Hot water and dish soap to clean for PETG, not alcohol. Consider a scotch-brite for cleaning as well.

Any suggestions for which scotch-brite?

Other rhan being dry, the tiniest lift will cause this. You may also need to tweak extrusion muktiplier (flow if live tuning)

Do you have a link for a howto for this?

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

Posted by: @aln-perez

Have you tried reducing the temperature by taking the lowest value plus 5° from the filament manufacturer (Example: 230°-250°, choose 235° and increase the bed temperature by 5° (if 80 go to 85°) these settings work for me.

No, I just used the default Prusament PETG setting, but I tried slowing the print of the base plate down. I haven't tried other temperatures.

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

[Arg, again this edit time out.]
On the package for the nozzle is 240-260, I tried 255, but you suggest I should try 240. For the heatbed is 70-90, I tried 85, and you say I should try 75?

RE:

On the package for the nozzle is 240-260, I tried 255, but you suggest I should try 240.

Again, I cannot edit, so I need to spam posts, I guess... I meant you mean I should try 245.

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

Have you tried reducing the extrusion multiplier to say 95% or 90%
sometimes the printer extrudes more filament than there is space for. 
with PETG successive layers cause the extruder to plow through the slightly raised surface causing particles of PETG to collect on the nozzle tip, 
these particles form into a small blob which eventually drops off (usually at the most inopportune time...) often causing a collision. between the nozzle and a hardened blob  from a previous pass of the nozzle 
reducing the extrusion multiplier during slicing will reduce the quantity of filament deposited by the nozzle, making layers less dense, reducing the chances of over extrusion causing nozzle pickup. 

No. And that is exactly what is happening to me. And now discovered that setting. It was set to 1. I will try lowering it to 0.9. Is extrusion multiplier when slicing and flow rate in live tuning the same?

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

Hi Pyro, 
Extrusion multiplier and flow rate are similar, but not the same, 
Extrusion multiplier is used during slicing, and affects every extrusion, adjusting the qauntity of filament  calculated for every move. (this can only be done during slicing)
Flow rate changes can be added to the Custom Gcode settings in Prusa slicer, and often there is a conditional item,  in the custom gcode, which sets the flow rate to 95% for larger layer heights. 
flow rate can be changed at print time,  and flow rate works by changing the calculated filament extrusion by the percentage, chosen... 

Note, if there is a conditional section in the custom gcode, of say 95%
and the extrusion multiplier is 1.0, you should theoretically end up with about95 Percent extrusion over all, 
if you then change the extrusion multiplier to 0.9  then the resultant extrusion will be 95% x 0.9 which equals about 85% extrusion... 

If however  you slice at extrusion multiplier 1.o and custom gcode flow rate of 95%, you should get 95% resultant extrusion as above, if you now adjust the flow rate during printing, to say 90% the printer will only re calculate the flow rate to 90%. not 85.5% as the extrusion multiplier option will calculate... 

Both options work. you just have to apply which ever option suits you best for your models... 

Often, adjusting the flow rate, gets forgotten if you print the same model more than once, where as, adjusting the extrusion multiplier, 'bakes' the change into Gcode, and yo don't have to remember to adjust the flow rate, next time you print the model. 

regards Joan

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

I only adjust flow in the tune menu to adapt an in-process print showing issues, that later gets translated into extrusion multiplier after specific EM testing. But it can save having to start over. I have also had to fiddle with temp, so far that seems more gelpful if retraction is sloppy from ooze. I'm still learning on this stuff, but Prusa does have some nice write-ups on some of this.

I've been using the green scotch-brite from the kitchen stash. No idea if thats the best one, but a lot of folks suggest the sponge with attached abrasive, and its usually the same as the green pads. My sink is right ny the water heater so always nice hot water. No lotions/softeners in the dish soap.

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

Thanks a lot everyone.

I ended up setting the extrusion multiplier to 0.9, this did most of it, but I noticed a small drop on the nozzle while printing, so I dropped the flow rate to 0.97, just for a couple of layers, then set it back to 1 for the rest. That worked wonderfully, and the drop didn't grow.

I'm from Germany, and scotch-brite isn't that common here, but we have abrasive dish sponges of other lables, which I uses. But I'm not sure that cleaning was the issue, as those are pretty new baseplates and I did clean them with alcohol and a microfiber cloth, and made sure that I don't have any dust particles on the plate.

Any hints about this issue that I could find were hinting to baseplate and first layer adherence issues, son I went there first.

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

there are a number of possible gotcha's when cleaning the build plate

Isopropyl Alcohol is not good at removing grease,    it is very good at spreading grease more thinly, over a larger area. 
which doesn't help adhesion

Dish soap contains surfactants which bond with grease molecules  allowing them to be washed away with rinse water... 

Microfibre cloths are sometimes are sometimes washed with fabric softener, which can also reduce adhesion... 

for me, dish soap and water works best. your mileage may vary.

Joan

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

Ahh, branded products that are the common term are a nightmare! As long as the abrasive cleaning pad is not metal I think all is good (though fine steel wool may do fine, come to think on it).

I use a soap without softener for washing microfiber since that also makes them less absorbent... But that's not the norm I bet. Paper towel is the safe bet. Even most dish soaps have lotions and such which are unhelpful for build plate cleaning.

RE: Nozzle tip accumulates material while printing the base plate (recycled Prusament PETG)

there are a number of possible gotcha's when cleaning the build plate

Isopropyl Alcohol is not good at removing grease,    it is very good at spreading grease more thinly, over a larger area. 
which doesn't help adhesion

Dish soap contains surfactants which bond with grease molecules  allowing them to be washed away with rinse water... 

Microfibre cloths are sometimes are sometimes washed with fabric softener, which can also reduce adhesion... 

for me, dish soap and water works best. your mileage may vary.

Thanks for the clarification. The article just mentions IPA, and dishwasher soap as a fallback: https://help.prusa3d.com/article/satin-steel-sheet_196526
To me the sheet looked perfectly clean, no grease marks or something. I avoid touching it directly with my fingers anyway.

Ahh, branded products that are the common term are a nightmare! As long as the abrasive cleaning pad is not metal I think all is good (though fine steel wool may do fine, come to think on it).

That is why I asked. Scotch-brite isn't common here and when I searched for scotch-brite, I got all sorts of cleaning products from 3M, including that steel wool. And I wasn't going to try that, without some reputable source confirming that. And TBH, I would still be careful. I wash the base plate before every print, and steel wool might just be to aggressive. Maybe only very limited in small areas that are really dirty, where it is easy to not scratch the underlying surface too much.

There are also different kind of abrasive dish sponges, more aggressive ones for pots and pans, and less aggressive for plates and such.

IPA with a microfiber cloth seemed to me the least aggressive, and non-corrosive and I don't want to cause additional wear, when it can be avoided. And with IPA is it clear whats inside, not so much for random dish soap. But apparently microfiber cloths cannot be trusted. and IPA's are not good enough remove grease.

Who knew that getting into 3d printing may even improve my house cleaning skills 😉