PETG/Filament building up on nozzle during large print.

[TheRiddick]

I have this really annoying issue and I can't determine if its because of over-extrusion or temperature or some other weird happening. I have read up on allot of issues similar to this one but not quite like my issue. The problem starts off VERY slowly by building up a tiny bit of filament on the nozzle each layer until by layer 5 or 8 the nozzle is completely covered in filament and printing fails.

I'm using PETG and was recommended to use 245c, I did try also 255c but same issue, if I go much lower the filament will struggle to come out of nozzle and the steppers will stop, maybe I can do 230c if I need too. Also I am using a tiny bit of olive oil on the filament filter but I don't see how that could affect it.

The other thing is I have extrusion multiplier set to 0.95 but have tried 0.90 and setting filament diameter to 1.69 (at 1.75 again) but no difference.

Anyway, what do people recommend?

PS. The bed is level and set to 70c... I will likely try 235c tomorrow, failing that i'll try 0.80 extrusion multiplier and see what happens, I gotta stop this micro-build-up of filament on the nozzle.

The Issue: (bad image sorry)

filament collecting on nozzle

[wirlybird]

One thing is you are making big changes. You shouldn't have to change the extrusion multiplier in such large amounts and if you do then something else is wrong.
Also, if you run the filament size down and it is actually bigger then you are increasing extrusion.

I print PETG at 235-240 I think (will have to check). I use basic ABS settings except for speed.

You don't mention the print speed. PETG doesn't print fast.

Usually when you get PETG dialed in and you still get build up on the nozzle you drop the extrusion multiplier by .01 or so but it is small.

[TheRiddick]

My calipers measure it as 1.69-1.72mm measurement. I was printing at 80mm/s but the first layer was only set to 60% of that and it starts building up a TINY bit of filament from the start (grows as time goes on to nozzle blocking levels)

[wirlybird]

That is extremely fast for PETG. I print at 2000mm/min or around 33mm/sec.

[TheRiddick]

I found a major issue with my printhead after closer inspection, the PETG was oozing out the threading also, so I redid the whole thing and changed the nozzle to the original version (basically same except not as pointed).

I will also print at 235c this time around. I'll leave the speed alone for the time being and see how I go, if needed I will slow it down.

[wirlybird]

I would research on the speed because I think that is really fast. Each to his own but just a suggestion.

Good catch on the nozzle though.

[dkightley]

Good catch on the nozzle though.

Did you really mean that??

[wirlybird]

It started as a "good job" finding an issue but digressed when I read it!