DIYer Bruno Martini needed a tool to precision cut metal for a CNC mill that he was building. Rather than buy a new set of tools or an expensive machine to get the job done, he decided to make a custom metal cutter using his handy 3D printer and some spare parts kicking around his workshop.
The setup is basically a Stanley hacksaw attached to a DC motor using 3D printed parts. A clamp is used to secure the machine to the table, while a piece leftover wood from a broken Ikea table provides the saw with some stability. The motor moves the saw over the metal, cutting it in the process. It takes a while to cut the metal, but it saved Martini from buying a costly tool or, even worse, from having to cut the metal manually. 3D printing was key to the build, allowing Martini quickly to fix a part that was incorrect. In the first version, the arm that attached the motor to the frame was not long enough. He lengthened the arm in the second version, but discovered it slipped when operating. It took three successive modifications to get it right.
Besides the arm, Martini also 3D printed a bearing holder that provides the pivotal movement of the machine. 3D printing made it possible to engineer this part witch such precision that it came off the printing press and held the bearings with no additional modification. The device also used two 3D printed holders that attached the hacksaw to a pieces of scrap wood for stability. To ensure they would last under this repetitive use, Martini used ABS in his custom delta-style 3D printer to build the parts. Several printed parts also contained 100% infill for added protection against breakage.
Martini demoed his hacksaw, showing how it cuts through a solid steel rod slowly, but surely. When cutting is complete, the resulting metal was machine smooth and did not have any burrs. It can be used right away without any need for filing. In his trial, Martin used the basic hacksaw blades, but in the final version of the machine, he plans to replace the standard blades with a pair meant for metal. Martini shared his project files online at YouMagine so others can download them and use them in their own projects. He also provided a full list of supplies on his website.