Each model was designed to carefully probe a single aspect of print quality. While not exhaustive, they test key aspects that are most closely related to perceptions of quality as well as functionality and performance. Each geometry was optimized for minimal material consumption and minimal print time.
Additionally, some probes, like the positive fine feature test and the overhang test, are designed to coax the printer into a failure state (extruder jam or geometry compile breakdown). Testing to failure generates more information than other testing strategies, offers a quantitative framework for evaluating print results, and allows for shareable evaluation protocols. Instead of subjectively evaluating how “blobby” a fine feature test is, you can create features that will reliably push the extruder into a failure state during printing. When the print fails, you can quantify the point of failure by measuring the height of failure with a set of calipers.
It’s often tempting to integrate all test features into one piece of geometry. While in some cases this is viable, combined geometry test prints are incompatible with testing to failure. Failed geometry may interfere with the proper compiling of other model features. Additionally, mixing test features changes the conditions under which the features are printed. For example, overhangs compile best when the previous layer has a chance to cool before the next layer is deposited. In a combination test print, overhang features may have additional time to cool between layers, potentially improving the printer’s performance on the feature. When testing overhangs in isolation, each layer has the same (and minimal) amount of time to cool, making for consistent and challenging conditions for each overhang angle. If the machine can compile all the overhang angles under these demanding conditions, it won’t have trouble with more integrative combined geometries.
In addition to evaluating this year’s crop of desktop 3D printers using more quantitative methods, we are sharing all the test prints and evaluation protocols so that others can replicate our results. The exciting implication is that changes to software, mechanics, and materials can now be correlated with changes in a specific quality performance quantity, providing a methodical, quantitative framework for evaluating and improving print quality.
Please use the “I Made One” button on your file sharing site of choice to share your results! Make sure to include the following information with your photo(s) of your completed test prints:
Andreas Bastian researches, designs, and builds new types of 3D printers. He has worked with FDM, SLS, DMLS, and SLA technologies and aims to make all more accessible. Currently a 3D printing research scientist at Autodesk, he is also active in the e-NABLE 3D printing prosthetics community.