Looking for an older CNC mill to refurbish/retrofit

I'm starting a search for an older CNC vertical/knee mill for my home shop and thought I'd introduce myself and ask for advice before buying something.

I'm currently looking at an older Wells-Index CNC mill, but I'm not committed to a particular machine yet.

My objective isn't to gut an old machine and replace everything. I would like to retain the original mechanical and electrical hardware where practical—including DC servos, feedback devices and possibly the servo drives/amps. The obsolete CNC control is another matter, it's a 70s vintage Bosch and going in the dumpster (or I might make it into a coffee table .  Thinking about LinuxCNC/Mesa.

Typical work will include aircraft instrument panels and other aluminum parts, but I also want a real mill capable of occasional work in steel.

I'm comfortable with electrical/electronic troubleshooting, software configuration, and I can spell Linux. My main concern is driving the old servo amps and are they serviceable and/or repairable.  I think the old brushed servo motors are OK. 

I'd appreciate advice from people who have restored or retrofitted older industrial CNC mills: What machines from this era are worth saving, and what should I inspect before buying?

Thanks in advance
 

Aircraft Instrument panels are larger than most knee mill tables.
Bridgeport Series II Interact have larger tables. Older Series II units have steppers.

It seems you need higher spindle speeds—8,000+ RPM. I have a thread on the forum about a Mori Seiki retrofit. I also work primarily with aluminum, and this mill would be too slow for my parts. That’s why I plan to build a DIY mill with a high-speed spindle; it will produce my aluminum parts faster and consume less power.

forum.linuxcnc.org/12-milling/49821-mori...ofit?start=20#349146

NoSmoke wrote:

I'm starting a search for an older CNC vertical/knee mill for my home shop and thought I'd introduce myself and ask for advice before buying something.
What machines from this era are worth saving, and what should I inspect before buying?

Thanks in advance
 

It's really dependent on your location.

Some makes/models just aren't available in certain locations.  @tommylight's suggestion of a Maho is fine if you're in Europe, but not in the US.

You'll want to find something local - if not, the transport costs will likely double the cost of an old machine.

And location also dictates - to some extent - the electrical supply you have to work with.

Power, at least in the US, is the primary bottleneck for many home-machinists.  You can hire riggers, build a giant workshop, pour a thick concrete pad... but if you don't have enough amps to your house/location (or your breaker/service is near capacity) then it will be very expensive to upgrade your electrical system to handle a 3-phase converter.  In this case you might still be able to run a Bridgeport-ish sized mill, but you will have to budget for a phase converting VFD as well as single-phase servo drives.

So...

Location?
Budget?
Power availability?  (i.e. what phase/voltage/amps do you have - or can get w/in your budget?)
Maximum work envelope?

Much of the USA is very rural, and in many places it can be more economical to buy and install a large generator than to get a large 3ph service from a utility.

Todd wrote:

Much of the USA is very rural, and in many places it can be more economical to buy and install a large generator than to get a large 3ph service from a utility.

All the farms around here can get 3ph drops pretty easily - or already have it.  It's really the suburbs and cities/towns that have an issue in this region (NE Ohio).

But I've no idea if those farms have "large" services or just enough amps to run some irrigation pumps and conveyors/fans/elevators.

I'm also NE Ohio (Wayne Co.) and I didn't think most of the farmers right around me had 3ph. But maybe that has more to do with the fact I'm on the edge of Amish country.

Todd wrote:

I'm also NE Ohio (Wayne Co.) and I didn't think most of the farmers right around me had 3ph. But maybe that has more to do with the fact I'm on the edge of Amish country.

They got the 0ph power.

I'm in Ashtabula, and our Amish have F350's, $10k kick-scooters, and 3 phase power that seems to be disconnected only when the Elders are around.

We have all flavors of Amish here. From ones like you describe to Swartzentruber Amish that will only use a couple kerosene lanterns on their buggies (they won't even use a smv triangle.) The ones like you describe may have a 50kw (or bigger) genset for their wood shop to run big CNC routers and other wood working equipment, but those wires run to the English city; das ist veboten.