I've thought about this a lot, myself. Haven't done it, but have run into a lot of different kinds of obstacles, which is why i think it isn't done more often.
1. Most of the old NC machines are big. Or at least big for a hobbyist. They're full size. Some are quite large. So at the very least you're looking at some significant expense in just the relocation and setting the machine.
2. Because they're mostly big, their parts are big. Many of them have rotary parts and tables that aren't coming off without a decent lifting system like a good forklift.
3. They're stripped. Sure, it might be fully profiling 4axis machine, but the knee block or chimney block was the first thing to go. Significant expense, that. Or whatever it is, you'll need some big tooling to get up and running.
4. Huge unknowns! Yuuge! Warped? Tapered? Canted? Binding? You almost never have any way of knowing. Remember, if it was running just fine, it'd still be in service. So something about it caused it to be sidelined. It could be an impossible board repair OR it could be a major mechanical problem. So even if it's in really good shape, it needs taken all the way down and precision inspected. Like the forklift, you'll need a full setup for that level of inspection. Today's lasers are fairly cheap though.
5. The documents are generally gone. These things shipped with phonebook sized manuals, sometimes, giving full schemes and the all the servicing measurements including critical dims. Without that, you're nearly blind.
6. What needs fixed? M A Y B E you can get replacement mechanical parts. M A Y B E you can get direct replacement ballscrews. P R O B A B L Y they used standard interface motors. Never know. The deeper you go, the more you're gonna find.
7. On the off chance you get all the above, it is possible to tie in at several points. You're bringing your own logic, so you choose about their controllers or yours; their amps or yours; their motors or yours; their ballscrews/nuts or yours.. you get the picture.
8. But finally, what has been the biggest problem for me has been the DPO. Generally, they regard their machine, up on 2x4s and covered with filth, to be a treasure. They'll have an unrealistically high price. It seems the longer it sits there, the more they think about the parts it could do when new in 1970, and not why, exactly, it was abandoned. They'll tell you how much a new one "just like this" costs. Usually, with me anyway, it ends with "I'll take it and GIVE it to the scrapyard before I sell it for less!" Maybe my negotiating skills are in need or maybe I live too close to Hall's (very overpriced) Machines. Either way, unless I can get into one for cheap, I'll still keep my eyes on a much newer, still-in-service model and skip the development curve.
Besides, i'm getting too old for that kind of stuff. Time flies too fast.
Wrat
