Few Hackaday Readers would disagree with the classic phrase: Necessity is the mother of invention. That statement is certainly no exaggeration when it comes to this mini 3-axis CNC Machine. The builder, [Jonathan], needed a way to prototype circuit boards that he designed. And although he admittedly doesn’t use it as much as he intended, the journey is one of invention and problem solving.
[Jonathan] started from the ground up with his own design. His first machine was a moving gantry style (work piece doesn’t move) and ended up not performing to his expectations. The main problem was alignment of the axis rails. Not becoming discouraged, [Jonathan] started on version 2. This time around the work piece would move in the X and Y directions like a conventional vertical milling machine. The Porter-Cable laminate trimmer would move up and down for the Z axis. It is clear that the frame is built specifically for this project. Although not the prettiest, the frame is completely functional and satisfactorily stiff for what it needs to do.
Each axis is driven by a surplus stepper motor and transmits power via 1/4-20 threaded rod lead screws. Bearings mounted in polypropylene bearing blocks are used to axially locate the lead screws. This is important because the stepper motor bearings are not designed to take axial load. Flexible couplings made from plastic air hose compensate for any mis-alignment between the motor shafts and lead screws.
An entertaining problem (for us readers) was encountered after some time of machine operation. Wood and PCB dust mixed with the grease used to lubricate the axis rails. This combination of materials turned into a glue-like substance making the axes difficult to move. A complete disassembly was required to clean out the gunk. Dry film lubricant proved to be a better choice for this application.
[Jonathan] encountered very common problems that face most CNC machine builders. His solutions were simple and effective and that is what makes this build great.