I need to build a power supply to power some 70 volt servo motors for my cnc router project, and I'm trying to get my ducks in a row prior to buying the components. Not having built a power supply before, any input from experienced/knowledegable readers is welcome.

I have a variable transformer that outputs 0-140 VAC and is rated at 4.5 amps and .63 KVA that I am considering (primarilly because I acquired it at auction with some other stuff some time ago, and it is not currently being used) so that I won't have to spring for a toroidal transformer. I'd like to get the full rpm from the servos. They are rated at 2.27 amps at Tc stall. I hope to power two of these servo motors with my power supply.

First, does it make sense to use a variac (since I already have one), perhaps mounted externally so that I can gradually increase the voltage? Second, does the aforementioned variac sound up to the task of powering the two servos? Third, should I stop now and go back to school?

All knowledgeable responses very much appreciated.