Pete, when buying a used machine it's all about who you gonna call, how ya gonna fix it, and where ya gonna get da parts?
As several have said, focus on more commonly available machines. I'd also consider focusing on machines that there are dealers for in your area, or at least close enough you're willing to drive over and chat them up if you need a part or some advise.
I think it's great that you're moving up after have converted your own machine. The knowledge you gained doing that should be invaluable.
Haas and Fadal have a reputation for being simple and easy to work on. The Matsuuras get brought up time and time again for being brutally solid machines that people make a lot of money with and that seem to last forever.
Something high end like a Mori Seiki I'd want to be real sure the machine is in solid shape. Replacing its spindle bearings or a ballscrew will shock the heck out of your budget.
Remember to hold back some budget for the usual suspects:
- 3 phase converter
- Tool holders and other tooling
- Set of books if it doesn't come with full docs
- New CAM to make it sing (see below)
BTW, was fiddling around with the G-Wizard Editor to see what kind of time savings a VMC might get you just for the heck of it. I started with a fairly complicated part program I had, one with 6 or 7 tools, but just 2 1/2D.
I dialed in a 60 second manual tool change, a 6K rpm spindle, and 100IPM rapids. The GWE simulator said it would run in 25:32.
I then went to a 3.8 second chip to chip tool change, which is the Haas Super Mini spec, time went to 18:58.6.
Then I cranked rapids up to the Haas spec, 1200 IPM and got 15:02.5.
Last step, crank up the feeds and speeds on the assumption you've got a CAM package that'll do an HSM (constant tool engagement angle, trochoidal, or what have you) tool path. Final number was 5:30.8.
So you just might be making parts 5x faster on the back of the envelope anyway, LOL.
Obviously every part is different, but it's fun to play with the numbers in the simulator (found a few bugs in the process, DOH!).
Don't underestimate the role of the "digital tooling" as well as the machine.
I look forward to seeing this come together for you. It seems to be a good time economically to buy a used machine.
Cheers,
BW
Try G-Wizard Machinist's Calculator for free:
http://www.cnccookbook.com/CCGWizard.html