Machine tools are expensive. To cut metal — even relatively soft metal, like aluminum — you need an extremely rigid frame. Physics and the economics of market forces being what they are, manufacturers achieve that rigidity using several hundred or even thousand pounds of heavy iron (or steel, if they’re fancy). The cost of the material alone, plus shipping all of that weight, quickly becomes substantial, and that’s before you get to the actual precision manufacturing and control electronics. But Chris Borge found a cheap workaround that let him design this DIY metalworking lathe that should cost about $100 to build.
The Open Lathe V1 is one machine in a series that Borge is designing. All of the machines in this series take advantage of poured concrete to achieve great rigidity at a low cost. The idea to use concrete for machine tool frames isn’t a new one. It seems to pop up every few decades, before disappearing again into obscurity. That is likely due to the complexity involved in creating forms into which builders can pour the concrete. And that’s where Borge’s design philosophy really starts gaining traction. His machines use 3D-printed forms that anyone with a basic 3D printer can fabricate.
This is Borge’s second attempt at designing a lathe constructed in this way. The first worked, but was difficult to construct and performed poorly—to the point where substantial spindle deflection is plainly visible in the video, even under a relatively light load. This new design solves both of those problems and seems to perform very well.
The brilliance of this design is in how the forms (hollow 3D-printed containers to hold the concrete) keep the other parts, like the spindle mount, in place while the concrete dries. Those complex forms would be virtually impossible to fabricate without 3D printing, but now they’re almost trivial with hobbyist printer models. And after the concrete is completely dry, the forms remain to give the lathe a nice appearance.
The cost to build the machine, which Borge estimates at $100-150 AUD (about $66-100 USD) is a result of filament, concrete, non-printable parts like the tailstock, and the motor. A complete BoM and build tutorial aren’t yet available (Borge is working on those), but the STL files are already on Printables.
Of course, this isn’t a high-precision machine and it may not satisfy machinists that work with lathes costing thousands (or tens of thousands) of dollars, but it is very affordable and should be good enough for most hobbyist needs.
