3D Printer Layer Thickness

Layer Thickness

One of the more important aspects of 3D Printer shopping is understanding layer thickness and how it translates to model quality.  Each layer in a 3D Print job represents a 2D cross section of the model.  The model is usually comprised of hundreds if not thousands of layers.  As these 2D cross sections are layered one on top of the other, the 3D object begins to take shape.  The thickness of these layers defines the vertical resolution of the 3D model.  Keep in mind this can be confusing depending on how the part is initially oriented for the build.  Models can be arranged in any fashion on many 3D printers, yet some require support structures that demands the model be oriented on a 4th independent plane.

Vertical vs Horizontal Resolution

In 3D Printing, there are currently 2 different types of resolution to measure the quality of the prototype.  First the horizontal resolution, or the dpi of the 2D cross sections.  This is measured in exactly the same way that a laser printer’s resolution is measured.  2nd, the Vertical resolution, or layer thickness, determines what degree of stair stepping will exist in the finished part.  Unfortunately to date, no one has come up with a formula to capture true resolution of a 3D printed part because dpi and layer thickness are 2 separate incompatible measurements.  This measurement which has yet to be defined could be labeled “Volumetric Resolution”.  Also remember that the stair stepping will occur differently depending on the build orientation of the part.

Stair Stepping

Assume for the sake of demonstration that you were to print 2 pyramid shaped objects and use the pyramid base as the true base for the print orientation.  Both pyramids are the same height, however each pyramid has a different layer thickness.  I liken it to the difference between a MesoAmerican step pyramid and and the Great Pyramids of Giza.  The step pyramid takes far less time to construct however it has thicker layers and so looks less like a true pyramid.  The Egyptian pyramids on the other hand took much longer to construct and have a thinner layer thickness. (if they were the same height)  This higher resolution (ie layer thickness) pyramid is then the one with the least stair stepping and most closely resembles a geometric pyramid.

Essentially, the smaller the layer thickness, the less stair stepping will be visible in the finished part.  But that also means a longer print time.  Many 3D Printers allow you to change the layer thickness settings before each build.

3D Printed layer thickness concept part3D Printed Layers