SpringFit: Joints and Mounts That Fabricate On Any Laser Cutter

Joints are crucial to laser cutting as they allow making three-dimensional objects; mounts are crucial because they allow embedding technical components, such as motors. Unfortunately, mounts and joints tend to fail when trying to fabricate a model on a different laser cutter or from a different material. In our survey of 200 models found online, 65% of models we downloaded from an online re-pository did not fabricate properly because of this. We trace this issue back to the way mounts and joints hold objects in place, which is by forcing them into is slightly smaller openings. Such “press fit” mechanisms unfortunately are susceptible to the small changes in diameter that occur when switching to a machine that removes more or less material (“kerf”), as well as to the changes in stiffness, as they occur when switching materials. Thus the issue with downloaded models. We present a software tool called springFit that resolves this problem by replacing the problematic press fit-based mounts with what we call canti¬lever-based mounts and joints. A cantilever spring is simply a long thin piece of material that pushes against the object to be held. Unlike press fits, cantilever springs are robust against variations in kerf and material; they can even handle very high varia-tions, simply by using longer springs. SpringFit converts entire models by replacing all contained mounts, notch joints, finger joints, and t-joints. In our technical evalua-tion springFit successfully converted 11/14 models from the web which fabricated in acrylic and wood and across different laser cutters. SpringFit is a first step towards what we want to call “portable” laser cutting.