Many Tormach customers start out by designing and building homemade CNC devices. Whether they’re retrofitting a manual mill or piecing together components to make a lathe. This week, we stumbled onto a metal lathe made out of concrete on Instructables. In fact, one of our founders, Greg Jackson, had a thesis in college that focused on adding concrete to drill press columns and cataloging the rigidity changes. While concrete can provide some similar properties to casting – some commercial machines even use a polymer concrete cast frame – it can fall short in a number of ways. Concrete has a tendency to heat up during the mixing and pouring process, which leads to cooling and shrinking as the material dries.