Service Learning Week 3 - Geometry for manufacturing from 3d scans

A common problem with 3d scanning is that the geometry you get from it isn't great for manufacturing. 3d scanners generate a cloud of individual measurement points which are converted into a mesh of triangles. That's all fine and dandy if you want to 3d print a part or render it in a computer generated scene, but what if you want to generate some real parametric design files that you can modify easily in a program like SolidWorks? Also what if you want to prepare the models for manufacturing on a 2.5 or 3 axis milling machine? Well that's the topic for this week.

The solution comes in reverse engineering software like Geomagic which Monterey Penninsula College are currently evaluating. Geomagic mixes aspects of 3d scanning software with aspects of CAD software like Solidworks to allow for easy tracing of models. That converts them from a cloud of points or mesh of triangles to a clean structure of shapes like circles with defined radii, fillets, and other parameters that are easy to modify.

To see what this kind of workflow might be like I setup a trial version of geomagic on a PC at MPC. Then I scanned an old pulley with their high end roland 3d scanner. This point cloud and incomplete mesh was imported in to Geomagic which allows you to perform operations to close gaps, smooth bumps, and trim excess data from the raw scans. With that work complete you get a finalized sealed up mesh which can be used for tracing.

Tracing the general pulley shape from the side created a new model of the pulley which is the kind of geometry you need for regular CAD programs that are for mechanical engineering instead of art/sculpture. The pulley could then be imported in to a large assembly, modified to fit different belts or shafts, and manufactured with CAM software. Overall Geomagic provides a great solution for converting these kinds of models and I look forward to examining the software more and providing a purchase recommendation to the school.