Mon
Jan
14
2008
Homebrew CNC Wooden Prototype
Unfortunately, I don’t have many pictures of this machine. In fact, I have no photographs. What you see here on the site is frames extracted from a video clip. It is hard to stop a project, pull out the camera and document what’s going on, but I’m working on it. Anyone who has tried to build a CNC machine knows that there is a pretty large learning curve. For me this was more like a learning wall. Not only was there the intellectual challenge of understanding all the systems, but I had no decent tools to manufacture anything precision. This was the primary reason for building a machine out of wood. Wood seems to be about 1000 times more forgiving than steel or aluminum and so it was a great place to start. The machine was built around a THK linear actuator that I aquired on eBay. Any homemade CNC machine should be built around the linear components since these are by far the most expensive part of any machine.
From the side view here you can see the gantry offset designed to maximize table usage. The gantry setup proved to be quite rigid despite its wooden construction. The weak spot would prove to be the Z axis.
The Z axis was pretty flimsy at first. In fact, what you see here, is the second attempt at making something “decently rigid.” Decently rigid is a title this machine never earned. Slight pressure could easily deflect the axis 1/4 inch or more. While not rigid, it did serve the purpose of a prototype, namely, identify the need for much more rigidity in future models.
The clamping table was nothing more than 1/4 – 20 nuts countersunk into a piece of 3/4 inch MDF in a one inch grid pattern. It actually worked quite well.
The CNC machine housed a 12vdc power supply imbedded in the table which powered some stepper motor chopper drivers from camtronics. These in turn drove my 1.4V 3.8A Vextra stepper motors. These proved to be plenty powerful. The startup torque was enough to really get the machine shaking during a cutting cycle. The speed was anything but steller. The poor performance was due to overly tight pitched ball screws and the low voltage power supply. After building this machine, I was hooked. It was time to move on to bigger and better.
