Motion Systems
This article makes the switch into an intermediate understanding of 3D printers. This guide would be useful when building your own custom 3D printer or studying the mechanics embedded deep in the system.
To understand how 3D printers work, we first need to explore their different motion systems, which control the movement of the Toolhead (Printhead) and sometimes the Build Plate. Below is a list of common types.
Cartesian Systems: Cartesian printers utilize three linear axes—X, Y, and Z—each with its own motor, enabling controlled movement along each dimension. For example, the build plate might shift along the X axis, allowing back-and-forth positioning, while the toolhead moves along the Y and Z axes. This setup provides precise control over where and how each layer is laid down.
Cartesian XY: A subset of Cartesian printers where the toolhead moves in both X and Y directions, allowing it to access any position over the build plate. Many desktop 3D printers use this configuration, with the Z-axis controlled separately. This approach is not limited to one type of printer, as different designs can still fall under the “Cartesian XY” category as long as the Toolhead moves in X and Y.
Bed Slingers (Cartesian XZ): Another Cartesian subset, bed slingers, are printers where the toolhead moves along the X and Z axes, while the Y-axis movement is handled by the build plate itself, which shifts forward and backward. This design, which is commonly found in budget, home 3D printers, provides stable layer stacking while maximizing build area. This configuration does not allow for high speeds, however, due to the weight of the bed that needs to be moved.
Core XY: This is a complicated subset of Cartesian that uses belts and stepper motors to move the Toolhead, but only does so in a very specific manner. This subset also dictates that there must be two (2) motors that control the X and Y movement. The complicated array of belts and pulleys makes it so that the two motors combine to move the Toolhead in an unconventional way. If both motors spin in the same direction, the Toolhead will move on the X axis. If they spin in opposite directions, the Toolhead will move on the Y axis. If only one motor spins, the Toolhead moves diagonally. This is one of the most commonly used motion systems in advanced home machines, due to its ability to move very quickly, decreasing print time.
Delta Systems: A lesser seen type of printer subset where the Toolhead roams on all axes, by using 3 ‘arms,’ each with its own specified motor. It can be extremely fast, and some current deltas, like the FLSun T1, are rated for higher top speeds than popular Core XY printers like the Bambu Lab P1S, though real-world speeds are much closer. However, it is incredibly tall, double the height of the average Core XY machine, which is great for printing tall items but can be difficult to find a place for in your home.
Polar Systems: A rare setup where the printhead only moves on the Z axis (vertically), and the Build Plate spins while sliding in a straight line out from its center, so there are no real X and Y axes. On some polar designs, the printhead does the sliding instead. These printers are uncommon due to their unconventional nature, which leads to lack of software being created and also more expensive parts.