Nozzle grootte en de impact bij afdrukken

Nozzle diameter is a much-discussed problem on 3D FDM printers.

Most 3D printers come standard with a 0.4mm nozzle. This means that the outlet of the printed plastic strip has a diameter of 0.4 mm.

The minimum layer height that we can define for our printer is NEVER determined by the nozzle diameter, but by the fluidity of the filament, or the minimum movement of our printer's Z-axis.

Colloquially, this is referred to as the ‘magic number’ of a 3D printer.

If we look at the best-selling FDM printers, they all use a stepper motor and screw shaft to define the Z-axis.

The minimum movement of the Z-axis is therefore determined by the number of steps the motor can take within 1 rotation and the pitch of the propeller (spike).

The most commonly used stepper motors for Z-axis drives have a step of 1.8°, which means that the minimum turn-on action is 1 command for the stepper motor of 1.8 degrees, or that the motor requires 200 steps to perform 1 full rotation.

Looking at the threaded rod used on the Z-axis, this is usually (on the most common printers like Creality) an 8 mm pitch screw. This means that if we were to put a nut on that screw and turn the screw a full rotation, the nut would have moved 8 mm along the threaded screw.

The minimum movement of our printer Z-axis is therefore 8 mm / rotation divided by 200 steps / rotation = 0.04 mm / step

The maximum layer height, on the other hand, is indeed determined by the diameter of our nozzle:

If we were to define layer heights above 70% of the nozzle diameter, the layers would no longer adhere as well, due to the rounding on the printed filament.

As we saw in the previous chapter, the diameter of the mouthpiece will determine the maximum low-frequency height that can be selected while still having good bass fixation.

Because the layer height can be directly related to the speed at which a print is finished (the thicker the layers, the fewer layers need to be printed for the same item), the nozzle diameter will have an even greater impact, as the wall thickness will also change with the nozzle diameter:

For the same wall thickness (let's assume 2.4 mm walls), the number of walls for different nozzle diameters would be:

Nozzle diameter	Wand dikte	Aantal wanden
0,2 mm	2,4 mm	12
0,4 mm	2,4 mm	6
0,6 mm	2,4 mm	4
0,8 mm	2,4 mm	3

As we can see in the table above, the thicker the nozzle diameter, the fewer walls we need to achieve the same wall thickness and thus print those items much faster.

Examples of slicing with different nozzle diameters and layer heights:
In the table below, we perform an exercise where we slice the same part, using the same basic settings regarding print speed, infill percentage, and wall thickness in mm. The top and bottom are always printed with 4 layers (will also vary in thickness due to layer height).

We will only change the nozzle diameter and the layer height and see what impact this has on the total print time.
REMEMBER: a thicker nozzle diameter will also have an impact on the printed infill, because the infill lines have the width of the nozzle diameter and are therefore thicker when using a larger nozzle diameter:
The layer height will always be a multiplier of 0.04 (the magic number for Z).
Example table of a print at 50 mm/s:

Nozzle diameter	Max  Layer Height  (0,7 * Nozzle diameter)	Layer Height	Wall thickness (mm)	Number of wall lines	Print duration
0,2	0,14	0,12	2,4	12	5 h 30 min
0,4	0,28	0,12	2,4	6	3 h 05 min
0,4	0,28	0,12	2,4	6	2 h 02 min
0,4	0,28	0,28	2,4	6	1 h 36 min
0,6	0,42	0,2	2,4	4	1 h 33 min
0,6	0,42	0,28	2,4	4	1 h 13 min
0,6	0,42	0,4	2,4	4	0 h 58 min
0,8	0,56	,02	2,4	3	1 h 18 min
0,8	0,56	0,28	2,4	3	1h 01 min
0,8	0,56	0,4	2,4	3	0 h 48 min
0,8	0,56	0,56	2,4	3	0 h 39 min

When using the same layer thickness but changing the nozzle width, the print time will change because we need fewer walls as the nozzle diameter becomes thicker.

IMPORTANT INFORMATION: Every layer adhesion weakens your piece, so more print layers also mean a stitch that will break somewhat easily in the horizontal direction.