[Chris Duncan]

Looking at a 1996 Matsuura MC-800VF, VMC

The only problem is the transformer on the power pole is only 25kVa (single phase) and the machine is rated 37kVa in the book specs and 41kVa, 200-220V, 118A on the metal plate on the back of the machine. The transformer was installed 1.5 years ago with a subsidy, to upgrade would mean full cost which is out of budget.

The RPC manufactures recommend a 40hp RPC for this machine.

Is it possible to run a smaller RPC that would work with the 25kVa transformer? Can I just run the machine at a reduced rpm/rapids/feed etc and get away with it? Can the machine/control be damaged if it goes over the available power?

the reason I'm asking is I put some money down without checking the transformer, assuming it was sized for multiple residences, which it's not. Otherwise I would just go to a smaller machine. But this one is low hours, a good price, and has a large envelope, plus I would lose the money down.

I'm not cutting Inconel at max rapids/feed. Mostly aluminum low volume prototyping.

[Chris Duncan]

So this leads to another question. Cart before the horse scenario.

Working from the other direction, fitting the machine to the existing available power. With a 25kVa transformer and 200 amp residential service, what is the largest maximum RPC that you could run?

[Jim Dawson]

Chris, you're correct, you have to start with the available power. That really sounds like too much machine for a residential service. The spindle HP is the controlling factor, and the RPC need to be sized to run the spindle. I have 100 amps, 240V, single phase available to my shop. So I limited the mill spindle HP to 7.5 running on single phase, and the lathe to 10 HP running on a 15HP RPC. You have to have enough power left over to run lighting, air compressor and other stuff.