The goal is to build a CNC router from 8020 aluminum extrusions. There are a number of impressive designs made entirely from MDF, UHMW, plywood and other low cost materials. These have all been a source of inspiration in some way or another. This is not my first CNC machine. I have previously converted a Harbor Freight Micro Mill to CNC, and designed and built a tiny router from 3/8" acrylic (nanoCNC). Both of these machines are too small for some of the projects I want to tackle. I have no intention of restricting the tools needed for building this router to commonly available workshop tools. This is not an Instructable - just a loose guide to building your own and detailing the essential elements of construction. Ultimately the picture below shows where we will end up, but that is jumping ahead a lot. If you can figure out what you need to do looking at the picture, then you can skip the rest of the blog! If you need more detail, read on....
Cutting area in the region of 18 inches X-Axis, 20 inches Y-Axis with about 4 inches of Z-axis travel. The size limitation is physical space in an already crowded garage, the added expense of going larger (extra support to keep things rigid over a longer span, longer lead screws or rack and pinion drive, more torque required from the stepper motors etc. you get the idea) and the additional technical complexities of a large router.
Material Cutting Capability
Must be capable of cutting hardwoods, MDF, plastics, aluminum and other non-ferrous metals. Aluminum requires a rigid machine. This is one of the reasons for using 8020 construction as apposed to MDF or other wood/plastic based construction materials.
It would be nice to be able to achieve 0.005" accuracy with repeatability of 0.002". Just seems like a decent goal.
40 IPM should be achievable. Not going to break any speed records but suitable for my needs.