Nozzle: what decides detail and print speed

What the nozzle does

The nozzle is part of the hotend. Filament is heated to melting point in it and pushed through a small hole, from which a thin line of plastic emerges. There is more on the principle in the Wikipedia article on FDM.

A nozzle is normally made of brass, which conducts heat well. For abrasive materials with carbon or glass fibres, hardened steel is used, because brass would wear down quickly (hardened nozzle).

Nozzle diameter and what follows from it

The most common diameter is 0.4 mm, and it is what we use. It is a compromise: it gives reasonably fine detail without the print dragging on for hours. A narrower nozzle (0.2 mm) draws finer lines, but printing is many times slower and it clogs more easily. A wider one (0.6 mm and up) prints fast and strong, but the detail is coarser.

The nozzle diameter also sets the smallest detail on a model. With 0.4 mm you cannot print a line much thinner than that same size, so walls thinner than 0.8 mm usually make no sense. See also wall thickness.

What can go wrong with a nozzle

• Clogging. Dust, dirt or leftovers of another material can partly block the hole, and the part is then weaker (clogged nozzle, under-extrusion).
• Wear. A brass nozzle widens over time, especially with abrasive filaments. That is why a nozzle is replaced as a consumable part.
• Wrong temperature. If it is too low, the filament does not melt enough, and if it is too high, you get strings and wisps.

The nozzle and your order

You do not set anything for printing with us. We work with a 0.4 mm nozzle and a 0.2 mm layer height, and the slicer calculates grams, time and price on that basis. When you design your own model, keep walls at around 1.2 mm at least and details no smaller than about 0.8 mm, or they may not print accurately.

Nozzle diameter affects print time, and that goes straight into the price. At the same layer height a wider nozzle lays down more plastic per minute, which is why large parts with wide lines are quicker. We use a single size, 0.4 mm, so that the result is predictable, and we therefore calculate the print price from the real grams and time from the slicer.

When designing, it is good to know that a nozzle cannot print a sharp inside corner. It rounds it to roughly the radius of the line, so around 0.2 mm. That is a few tenths of a millimetre, but for precise fits it has to be taken into account.