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Error correction layer shift in 3D printing

Shifted layers in 3D printing

Most 3D printers use a controller that does not allow any feedback on the position of the print head. Put simply, this means that the 3D printer simply tries to move the print head to a certain location. However, the printer control cannot recognize whether a precalculated position has actually been reached. In most cases, this works quite well without you noticing any negative effects, because the built-in stepper motors are strong enough to pass small obstacles (e.g. a small drop of filament) without impairment. However, if you interfere with the movement of the print head (e.g. by pressing it a little), you will find that the printer control does not notice this. As a result, the 3D printer starts its work at a different point than the precalculated in the gcode. Once a shift in the layer occurs in 3D printing, there is unfortunately no way of correcting this error afterwards. However, by observing the printing process, you may be able to intervene early on before an error actually occurs in the print image.

Print head moves too fast

At very high speeds it can happen that the stepper motors of your 3D printer are overloaded and therefore no longer perform the exact number of steps than would be necessary for an exact movement. So if you try to run your 3D printer at faster speeds than the motors can process, you will typically hear a click as soon as the motor does not reach the desired position. When this happens, all subsequent parts of the 3D printing will be offset in relation to the parts previously printed. You can see this from a more or less prominent step within the component. This effect can only occur after the stepper motors have been running for a while and become very hot as a result. You would only notice the error with larger or more complex components, not with small, simple objects.

If you think that the print head of your 3D printer is moving too fast, try to reduce the printing speed by 50% and watch the printing result afterwards. Reduce both the printing speed and the movement speed in your slicer software. The print speed controls the speed of movements in which the extruder is actively extruding plastic. The speed of movement controls the speed of fast movements in which no plastic is extruded, i.e. the printhead "jumps" from one point to the next. If one of these speeds is set too high, shifts in the layers can occur. In theory, you could also change acceleration settings in the firmware of your 3D printer. However, we strongly advise you not to do this if you do not know exactly what to set there and how. In the worst case, you will lose your warranty claims or your 3D printer will fail completely.

Mechanical or electronic problems

If the shifts in the layers persist even at low speeds, this could indicate mechanical or electronic problems with your 3D printer. Most 3D printers use toothed belts to drive their axes, which are made of neoprene or polyurethane and usually have a layer of fiberglass for stabilization. Over time, these belts stretch a little, resulting in poor belt tension, which in turn affects printhead positioning. This is particularly the case when the toothed belt becomes so loose that it occasionally skips the teeth of the drive. The effect is quite similar to the lost steps effect of the stepper motor. Conversely, a belt that is too tight is also a possible cause that a stepper motor cannot generate enough force.

Therefore, first check the tension of the toothed belt. These must be tight enough to prevent skipping in the drive gear. On the other hand, they have to be loose enough that the stepper motor can still move. In the next step, check whether the pulleys that are attached to the stepper motors are tight. Usually the pulleys are fastened with a small grub screw with a hexagon socket. Check for each (!) Belt pulley whether it can be turned on the motor mount without the motor turning. If this is the case, carefully tighten the grub screw until the pulley can only be moved together with the motor.

If all mechanical sources of error are excluded, electronic problems can still be considered, which lead to step losses in the stepper motors. The following sources of error are mentioned as examples, but they are not a complete list of all possible electronic error sources:

  • Insufficient voltage supply to the stepper motors
  • Overheating of the drivers
  • Leakage currents on the circuit board

Unless you happen to be an electronics technician, you should have electronic sources of error checked by an expert. Knowledge of the electronic components, how they work and their necessary power supply is required here. Therefore contact the manufacturer of your 3D printer after excluding all mechanical sources of error and if you suspect electronic problems.