Ovidiu Predescu's Weblog

Make your own hardware parts

Some time ago I was looking at a way to build some hardware parts for a small project I want to do at home. I found the emachineshop solution to be fairly expensive and with huge lead times, sometimes in the order of months.

I did some more research into how can one like me, with only software experience and a limited understanding of mechanics, build his own parts. Learning to use an old fashioned mill to make your own parts doesn't sound too enticing: you cannot install such a machine in your garage as they tend to be really huge, heavy and noisy.

The manufacturing industry is using the so-called CNC machines - Computer Numeric Control. Using relatively simple instructions in a custom programming language called RS274 (or G-code), you can tell a machine what to do. You can design a part using a CAD application, and have the application generate instructions for a specific machine in the RS274 language.

The RS274 language is interpreted by a computer which then drives stepper motors on the CNC controlled machine (mill, lathe, router etc.). Usually these programs and specialized computers cost thousands of dollars. However the Linux CNC project maintains EMC, a free-software implementation of the RS274 language, that runs on a Linux system and can drive motors through a special driver attached to the parallel port. I found one company, Sherline Products, that builds and sells CNC mills and lathes driven by EMC. You can buy such a mill for less than $2,000. For the ultimate system, their 8620 package gets you a mill and a lathe for some $4000 (if you don't buy their computer).

As far as software is concerned, it would be really cool to be able to draw your part in an application and see it in 3D, then tell it to generate the G-code for the machine to build it. SolidWorks appears to be one such application, although very expensive. I'm still looking for such an application, especially one running on MacOS X rather than Windows.