Material burns on a nozzle.

[Hokololo 2]

Hello all,

I'm very new to this 3d printing world. And, so I'm having many troubles with it.

Here is one minor issue that I have, but cannot easily solve it myself. So, I wish to have some help.

The issue is a burnt material dropping into the model.

As you see in the picture, the material burnt on the nozzle, and it caused many black dots on this nGen transparent material.

I know this is not the serious issues, as this is not a fail of print. However, it is very annoying since I wanted to have a clear object.

The same thing happened when I used PVA. So, I suppose that I'm missing an idea to avoid this kind of problems. I'll appreciate any help.

My setting parameter is like this.

Layer height 0.1

Printing temp 220

Bed temp 75

Retraction Distance 4.5

Retraction Speed 45

Print Speed 50

Fan 100%

[tomnagel 123]

It's a known problem, and I have not yet seen solutions.

If you want to experiment a little, maybe you can try to put some (high temp resistant) oil on the outside of your nozzle.

[kmanstudios 1,120]

I have found that dropping my PVA temps to help a bit. It also depends on how humid your environment is.

While I have a roll of Ultimaker waiting to be used, I am experimenting with Matterhackers PVA and I print with it usually at about 200°-205°.

It did greatly reduce the amount of junk. Still burns a bit on the outside when humid, but not so much dropping of bits.

[geert_2 556]

It is best to clean the nozzle's outside after every print, so that no black residu builds up. I usually do this immediately as soon as the print finishes: just wipe it with a paper cloth, when still hot. But you can do it later too, after warming up the nozzle a bit.

Wiping the nozzle with silicon oil prior to starting a print also reduces build-up of residu for some materials (PLA), but less with others (PET), in my experience.

Reducing temperature and making sure you have no overextrusion may also help.

[kmanstudios 1,120]

It is best to clean the nozzle's outside after every print, so that no black residu builds up. I usually do this immediately as soon as the print finishes: just wipe it with a paper cloth, when still hot. But you can do it later too, after warming up the nozzle a bit.

Wiping the nozzle with silicon oil prior to starting a print also reduces build-up of residu for some materials (PLA), but less with others (PET), in my experience.

Reducing temperature and making sure you have no overextrusion may also help.

I second the cleaning the nozzles after every print in the highest order. Both nozzles for me because the other nozzle may pick up stuff. Also, some of the AA core type materials are hydroscopic and will sizzle and crackle like PVA. So, I just hit them each time a print is finished.

In addition to what I said about the temp. drop, keep in mind that the idea is to drop it low enough to reduce the carbon build-up, but still allow flow. Different material manufacturers have different qualities.