Design: This iteration was properly designed in 3D CAD before being fabricated; previous iterations were just done on-the-fly with the parts I had on hand, with "upgrades" bolted on along the way. I didn't base the design off of any existing mills, though it undoubtedly bears some similarity to a number of them.
Parts: A while back I decided to just "do it right". That means nice ballscrews, real linear bearings, and a whole lot of metal keeping things rigid. Most parts were sourced from eBay, except the metal stock. I got that from my local discount metal store.
Fabrication: I built the whole thing myself, using a mill and a drill press, plus a whole lot of time. I'm really not a great machinist, so setting up the cuts and aligning them took forever. Once the CAD was done, it was probably a couple months of work to get the machine put together and running.
What's been upgraded since the first version: Everything except the steppers (which might benefit from an upgrade, but are mostly fine).
- Third spindle (Dremel, nicer Dremel, real 1.5 kW spindle)
- Third Z axis (drawer slides, bushing-based linear stage, custom-built with linear bearings)
- Third power supply (24V, 48V, new 48V after blowing up the first)
- Second set of bearings on X and Y axes (drawer slides to linear bearings)
- Third set of leadscrews (1/4-20 hardware store threaded rod, ACME rod, ballscrews)
- Second mechanical frame (first one was a cut up tabletop, now 3/8" aluminum plate)
So a long-running project to get to this point!