MIT 2.77 FUNdaMENTALS of Precision Product Design

Design Modules for FUNdaMENTALS of Precision Product Design

This page serves as a portfolio of my work completed in Professor Alex Slocum's 2.77 FUNdaMENTALS of Precision Product Design course at MIT. For more information about the course please visit  the course website.

two aluminum plates one with three sets of two dowel pins and the other with three balls, each having a magnet in the center

kinematic coupling

In this module I designed, manufactured, and tested a kinematic coupling. Kinematic couplings are exactly constrained interfaces where six points of contact uniquely constrain six degrees of freedom of motion. My coupling used common materials including steel balls, dowel pins, and neodynium magnets to achieve positioning accuracy better than 10 μm (the limit of my measurement resolution.  

elastically averaged coupling

In this module I designed, fabricated, and tested an elastically averaged coupling. The coupling was designed to allow repeatable and precise alignment between two plates. While I did not have a specific application in mind, this coupling would be useful for precisely mounting any number of machine components and will likely be adapted for use in my T-Base mill project. My design requirements for the coupling were repeatability better than 10 microns (the extent of what is measurable in the lab) and high stiffness. Here high stiffness means stiff enough to stay in place while a more permanent bond between the plates is made with an adhesive or rivets or bolts.  
Orange Acryllic Plates Used for Elastically Averaged Coupling

elastically averaged coupling - Measuring accuracy

This week I revisited my elastic averaging coupling analysis to include an analysis of coupling accuracy. My last elastic coupling prototype did not have reference features for measuring coupling so I revised the coupling to include those features and tested accordingly. The redesigned elastically averaging coupling (EAC) prototype includes a ¼” hole through the center of both the top and bottom plate. The sole purpose of this second prototype was to measure the improvement in repeatability gained by utilizing elastically averaged couplings. Thus, last week’s requirement for high stiffness was relaxed and the design was modified to be made from acrylic.