I've been lurking around this site for some time and have always wanted to build my own machine. I shied away from starting a build because I questioned the longevity of an epoxy granite frame, though some of the machines I've seen built have been impressive, and because I had no interest in making my own steel frame because of the machining required after. My main interest at the time was building a VMC, until I saw a Datron in action. I then started researching about making CNC gantry machines with a granite base, and that's when I stumbled upon @fox3d 's granite gantry machine, can be seen here:
https://www.cnczone.com/forums/epoxy...54358-cnc.html
I was surprised at how well the machine cut with his spindle set up. Shortly after, I found myself looking into large surface plates, needless to say I was blown away by cost of some of these plates. Once they go above 18"x24" the price sky rockets. I then started looking at some featured at auctions, and out of curiosity I wondered how much these large surface would plates sell for. I placed a $1 bid and about a week later, I received an email notification that I had won a 36"x48"x8" surface plate and that had a few days to pick it up. I was completely taken by surprise and now had to figure out how I was going to move this 1,000lbs+ monster piece of granite.
Once I got the surface plate home, I began taking measurements and started modeling it in SW.
This is what is what I have so far:
25mm Hiwin rails on X, Y and Z.
Ball screws: TBD
Control: Centroid Acorn? I would like to rigid tap, and be able to run HSM tool paths without the control slowing down.
Spindle: Jianken is up there on my list, but still researching, so I am open to suggestions. I'm thinking 15k-20k spindle with ATC. I mainly plan on using a 1/4-3/8" end mills, maybe 1/2" once in a while. I would like to be able to drill 1/2"-9/16" max, with 0.159-.3125" being common.
Gantry: 6" x 12" x 63" long, 0.250" wall tubing.
I plan on only cutting aluminum on this machine, so the machine will be fully enclosed to keep chips and coolant inside.
Machine travels: X - 48", Y - 30" and Z - 12"?, these specs may change as the design progresses.
Any recommendations for sources for ground ballscrews, Hiwin rails and servo motors are welcomed, and what places/brands to avoid is also appreciated. Any feedback and input on the machine design is also welcomed. If you think I am making a mistake, please point it out.
Here is my machine in its current design stage: