CNC-related projects

The original parts do make a functioning machine, but each of them is only barely adequate for its job. However, I do acknowledge that this is an inexpensive machine and I would still recommend it as a "good start" for someone who wants to learn by upgrading it.

Since I was inexperienced at first I wasn't aware that some of the limitations causing me to struggle were shortcomings of the machine and not me.

Over time I've improved the machine with:

• an upgraded spindle motor that has a real closed-loop speed control (bought from Sherline) that allows you to select a spindle speed and maintain it through various loads.

  Cutting plexiglass or nylon is impossible with the original speed control since you cannot maintain a slow enough speed to keep the material from melting. If you set it slow enough, as soon as it touches the material the motor bogs down and stops, and then the tool breaks off.

• a new motor mount that is more easily adjustable and much more solid than the original "two toothpicks" scheme.

• tool holders that allow me to preset the depth of the tools to be all the same. Milling a circuit board requires first an end mill for roughing, then the V-shaped tool used to cut around traces, then several drill sizes, then the end mill again to cut out the board. Depth across tool changes has to be exactly right and re-zeroing the Z axis all the time would be tedious. I would not want to be without these holders. These were made for me by Don Panzer of D.P. Design. Don's business card says he specializes in prototypes and small parts and does custom anodizing and machining. These tool holders are his design and they work great and were affordable. He also made a couple custom holders that work with my various miniature Jacobs chucks.

  I contacted Don and he gave permission to link directly to his email address DpDesign@covad.net. He also says he is going to make up a web page just to show off the different MaxNC accessories he makes. I look forward to seeing what else he has come up with.

• high-voltage stepper motor drivers that use a chopper instead of ballast resistors to limit current, allowing rapid speeds of about 32 inches/min instead of the abysmal 10 that the original drivers allowed. More information about my stepper driver setup here. The machine still has the original stepper motors, but they are the optional higher-power motors that were sold by MaxNC at the time.

• simple spring-loaded zero-backlash nuts (my own design) to allow the machining of printed circuit boards. These have now been replaced with plastic zero-backlash nuts and acme leadscrews, but I don't have a new photo yet.

• EMC, the Enhanced Machine Controller: software written originally by NIST and enhanced by many people since then, including me.