10-27-2019
Today marked the first day of work on the initial physical prototype. Our work pace exceeded expectations and we completed one side of the frame up to, and including, tack welding. The main goals for the day were to assess best practices for measuring, cutting, and mitering the steel tube, validate the frame jig’s functionality, and lay out all finished pieces to check geometry.
We’re using 1/8” wall steel, which proved fairly difficult to cut with a chop saw. All measurements were all based on technical drawings created from the CAD design and hand scribed, which added a layer of error to the final part dimensions. However, the frame jig held the tubes firmly enough to preserve overall geometry and allow us to fill any tube-tube gaps when tack welding.
While tack welding, we began to notice the bottom tubes were slightly raised compared to the rest of the frame. This can largely be attributed to the thin plywood construction of the frame jig, which flexed under the weight of the steel. For an initial prototype, this slight deviation from coplanar isn’t a huge concern and will likely have minimal impact on riding dynamics. For subsequent prototypes, a significantly more robust and planar jig will be made, likely out of thick CNC-routed plywood.