Don't assume that all CNC and milled-out pieces are engineer-designed an machinist-made. My team, for one, has a core of machinists who are trained on manual mills and lathes, with a specialized group of three people (including me) who are trained on the CNC mill. Our sponsorship from a nearby machine shop consists of them letting us use their tools, with the stipulation that they're too busy to make parts for us. All of our parts are student-designed and manufactured, but they're very high quality.
However, if you accuse our robot of being engineer-designed and built, we'd be flattered
Very nice sprocket btw. I count only two bolt holes - that enough? Are the holes made by waterjet too?