Regarding size -- it all depends on what type of machining you are doing. Is this a vertical or horizontal milling machine you're after? The most popular garage machines are vertical milling machines. Usually pre-owned Bridgeports are where you get good prices. Then, back to size matters -- you should get the largest machine that your budget will handle. For example, a Bridgeport with a 42" table -- or if you are not earning a living on this machine, foreign machines like Enco or Jet can also be found at bargain prices. I'm a little concerned about your 100amp box because the machines at our home are run on 220 single phase and many of the used machines for purchase may be set up for 3 phase where you need a phase converter which may be able to operate on your 100 amp service. Hope this is helpful.
Because I don't check this forum every day, if you'd like to contact me directly, my email is daveblood2011@gmail.com.
Because I don't check this forum every day, if you'd like to contact me directly, my email is daveblood2011@gmail.com.