Even if all your settings seem to be set correctly, the unexpected can cause issues with your prints.
Signs of burnt stuff dripping on your print:
See the drop of brown molten ooze on that picture there? It not only looks poor, especially if it lands on one of the outer surfaces, it can ruin your print when your HotEnd hits it on the next pass. We’ve had multiple cases where a drop like this damaged some of our (cheaper) printers. So, let’s try and avoid this.
Explanation:
Most commonly due to build up on the nozzle of a leaking HotEnd, but can be worse with certain materials.
How to fix:
Clean the outside of the nozzle
Over time your nozzle tends to pick up traces of molten material, due to over-extrusion or warping or similar. It happens. Clean your nozzle between prints. We’ve seen printers where you’d be hard pressed to tell the original colour of the nozzle installed (or if there is a nozzle at all!).
Calibrate extrusion
Calibrate your extrusion rate, over-extrusion will lead to more build-up.
Leaking HotEnd
Your HotEnd might be leaking. Especially on cheap kit printers the HotEnd or nozzle is often installed wrong. As basic rule: the nozzle needs to be tightened against the throat of the heat break and not against the heater block.
Clean the HotEnd, then start a few more prints. Pay close attention to where the filament is appearing again – is it getting picked up by the tip of the nozzle eventually wandering upwards, or does it appear at any of the threads around the heater block first?
Filament specific tips:
PETG especially tends to gather on your nozzle, accumulate during the print and eventually drip. This (and its sometimes-excessive adhesion to certain build plate surfaces) is why we recommend not squishing your first layer when printing with PETG.
When printing Wood particle filled filament the polymer binding agents (cellulose resin and/or viscose blended with PLA) tends to drip from your HotEnd in a honey like consistency when printing to hot. Or after it sat in a heated nozzle for a while. Print colder and at a constant speed.