Building a good quality machine shop may seem to present a chicken-and-egg problem, at least for anyone not willing to mortgage their home for the money needed to buy all of these tools new. Namely, that building good tools often requires good tools. To help solve this problem, [Ryan] designed and built this CNC machine which can be built with nothing other than common tools, hardware store supplies, and some readily available parts from the internet.
Since it’s being built from consumer-grade material, [Ryan] has the design philosophy of “buying precision” which means that most of the parts needed for this build are precise enough for their purpose without needing to be worked in any way before incorporation into the mill. For example, he uses a granite plate because it’s hard, flat, heavy, and sturdy enough at the time of purchase to be placed into the machine right away. Similarly, his linear guides do not need to be modified before being put to work with a high degree of precision and minimal calibration. From there, he applies the KISS principle and uses the simplest parts available. With this design process he is able to “bootstrap” a high quality mill for around $1500 USD without needing any extra tools than the ones you likely already have.
The RIG-CNC as it is known has also been made completely open source which further cements its bootstrapability, and there is a lot more detail on the project page and in the video linked below. This project is unique not simply for the mill build from common parts and tools, but because this design philosophy is so robust. Good design goes a lot farther in our builds than a lot of us might realize, and good design often results in more maintainable, hackable things that work for more uses than the original creators may have even thought about.