One of these 5 Axis Moving Table CNC Machine - Diversified Machine Systems (but older)? I doubt these sell for under $100k, even used, so if you can get it running for $20k it's probably worth doing. Did the previous owner tell you what, if anything is wrong with it? Is that an active counterbalancing cylinder, or just a gas strut? It's normal for these things to be disassembled for shipping, so the fact that things are in pieces is not a really bad sign by itself. If it's been sitting around a while, it's also normal for a few things to get lost, if it's been decommissioned a while. Did it ever have a tool-changer? The motors are probably fine, although I'm sure DMS would be happy to upgrade them for you. The computer is likely to want upgrading more than the motors, though; that's probably where DMS will be most useful. I'd say put it back together yourselves, hook it up, and see what it does. Who knows - maybe it will fire right up and work okay.
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