Sharp corners are often specified in product design to maximize the interior volume of
a component, facilitate mating between components, or for aesthetic reasons. However,
sharp corners in 3D Printing should be avoided for many reasons related to product
Relative to product performance, sharp corners will result in a stress concentration that
may cause many (and especially brittle) materials to fail under load. Furthermore, a box
with sharp corners and tall sides may not have the torsional stiffness of a rounded box
with shorter sides.
Some common guidelines for filleting and chamfering corners are provided in Figure 1.0. As
shown, the fillet radius on an external corner should be 150% of the wall thickness. To maintain
the same thickness around the corner, the fillet on the internal corner is set to 50% of the wall
thickness. In most modern, solids-based design programs, these fillets can be readily achieved
by filleting the outside edges prior to shelling of the part. These fillet recommendations are
only guidelines. In fact, even larger fillets should be used if possible.
Figure 1.0 [D.Kazmer. Injection Mold Design Engineering. Hanser]
Another important thing in designing 3D Printable Parts is direction of laying the layers in terms of strength. In Figure 2.0 is this described how it should be.
In fact, the part should be set that the force is in the direction of the layers, not the norm of the layers.