Game developer and eternal learner [David Tucker] just posted a project where he’s making linear flexures on a 3D printer. Tinkerer [Tucker] wanted something that would be rigid in five of the six degrees of freedom, but would provide linear motion along one axis. In this case, it is for a pen or knife on a CNC flatbed device. [David]’s design combines the properties of a 1-dimensional flexure and a spring to give a constant downward force. Not only is this an interesting build in and of itself, but he gives a good explanation and examples of more traditional flexible constructs. He also points out this site by MIT Precision Compliant Systems Lab engineer [Marcel Thomas] which provides a wealth of information on flexures.
Shown in the relaxed state
Shown in the fully compressed state
[David]’s experiments showed that leaf-spring-like segments with a thickness of 0.4 mm provided the desired amount of force. We’re not sure how many iterations were required to arrive at this number — perhaps those mechanically inclined readers can offer up equations to predict the spring force ahead of time for a particular geometry. Even though printing springs of a precise force may be trial and error, at least 3D printers are good at making precise and repeatable thin-walled structures. Also note that since the spring force only needs to act in one direction, pushing into the paper or other working material, the spring design is asymmetric.
This approach is basically a living hinge of sorts, so there c ..
Support the originator by clicking the read the rest link below.
