The hotend of many common 3D printers is fitted with a 0.4mm diameter nozzle as standard. This nozzle is often retained and then exchanged for a nozzle with the same diameter after a certain period of time or as soon as it is worn or blocked.
However, it is worth considering replacing the 0.4mm nozzle with a nozzle of a different diameter.
Pros and cons of other diameters
A nozzle with a larger diameter can have advantages. The larger diameter increases the wall thickness for one extrusion width. Therefore, fewer wall lines are required to achieve the same wall thickness. This in turn results in a reduction in the printing time. The larger diameter also makes it possible to increase the layer thickness (note: be careful not to go above 0.2mm for Braille). The maximum theoretical thickness of a print layer is 50-75% of the diameter of the nozzle. Some slicers allow you to adjust the layer height depending on the specific accuracy required. Areas with a lot of detail are printed using a reduced layer height, while simple structures, for example a vertical wall, are created with larger layer heights, making the printing process more efficient.
However, this advantage comes at the price of not being able to print fine details, or at least not as well, with a larger nozzle diameter. With a thicker layer, the layer lines are also more visible. It is possible to work with different nozzle diameters and layer heights in a printer with more than one extruder.
As well as the standard 0.4mm, there are also nozzles with a smaller diameter (e.g. 0.25 and 0.3mm). However, these are not necessary for our purposes and are not suitable due to the vastly increased printing times and the significantly higher risk of a clogged nozzle. Last but not least, some filaments (e.g. with particles) are not compatible with small nozzles.
Recommendation
A diameter of 0.6mm is a very good compromise between reduced printing time and maintaining the required level of detail. A layer height of 0.2 to 0.25mm should be possible with any FDM printer with this nozzle.
Nozzles with a thickness of more than 0.8mm proved to be less suitable for printing braille in tests and first quality deteriorations occur from a diameter of 0.8mm.
Nozzle material
Brass nozzles
The most common print nozzles are made of brass and are therefore robust enough to print most filaments. Compared to alternative materials, brass is inexpensive and its excellent thermal conductivity makes it a very suitable material. Almost all 3D printers come with brass nozzles as standard. Brass nozzles can be heated up to about 300°C.
Coated nozzles
To protect the soft brass from abrasion and to reduce friction between nozzle and filament, brass or copper nozzles are also available with nickel or chrome coating.
This coating also increases the temperature resistance to about 500°C.
Although these nozzles have advantages over the normal brass nozzle, they are not as hard as hardened steel and are therefore not suitable for permanent use with abrasive materials.
Stainless steel nozzles
Stainless steel nozzles are hard and therefore have better wear resistance. They also prevent the print from being contaminated with lead, which can sometimes be the case with brass nozzles. For truly food-safe 3D prints, a stainless steel nozzle must therefore be used.
Compared to brass, steel is less heat conductive and more expensive. The temperature resistance is around 500°C.
Hardened steel
If abrasive materials such as wood, carbon or metal fibres are to be printed, a hardened steel nozzle should be used. Hardened steel is about 10 times more wear-resistant than brass.
However, the material has a lower thermal conductivity and is more expensive to purchase. The print quality of steel nozzles is also often inferior to that of brass nozzles.
Brass ruby nozzles
Nozzles with ruby tips belong to the luxury class of 3D printer nozzles. Usually, ruby nozzles are brass nozzles with a ruby at the tip. Since the bore in the ruby can be manufactured very precisely, there are only small diameter tolerances, which means high quality.
Compared to the other types of nozzle, the ruby nozzle is the most expensive. Brass ruby nozzles have an extreme temperature resistance of around 500°C.
Recommendation
Since abrasive materials are rarely printed in our particular field of interest, a brass nozzle is almost always sufficient. These are cheap to buy and can therefore be replaced from time to time without any problems. Ferrous materials can be printed with a hardened steel nozzle. However the extruder drive must also meet the necessary requirements with regard to abrasion.
