The air compressor in my jump starter broke its connecting rod. I decided to try rebuilding it. I could easily machine one from bar stock. Since it’s a small part, it could be printed in aluminum relatively cheaply. I’ve wanted to see a printed aluminum part for some time. So far, it seems to be holding up ok.

October 6, 2022: I’ve decided that I don’t really trust the printed aluminum rod. It seems really flexible and that may be contributing to the compressor not pumping like it used to. I’ve CNC machined two replacements in steel. The more robust one will eventually find its way inside and I’ll see how it works. The part pictured in the vise and chuck is not the final part. I miscalculated the size stock I needed to start with resulting in the uncut areas. It was re-cut from larger stock. The holes were spot drilled while the part was still on the mill so they would be accurately located. I waited to drill them through until the part was faced to thickness to avoid deforming the holes.