As the subject says, suitable for a 3hp lathe. And in the essence of Locost........

Big capacitor(s) !

The motor will provide 80% of full power and be easier to stall but once running you will be okay.

Alternative is to build a rotary convertor (Big capacitor and a free running 3 phase motor) like this.

http://www.metalwebnews.com/howto/phase-converter/phase-converter.html

I run a 24" 3hp power hacksaw with a bunch of capacitors only from Ebay for £10, kept adding capacitors until it started cleanly, then removed some until it ran smoothly (motor grumbles if you over do it when its up to speed)

A power hacksaw has a heavy initial load when starting, you may not need additional capacitors to start a lathe.

Use ex amy oil cooled AC capacitors, get 10 x 22uF as a starting point and keep bolting them in.

Regards Mark

Not good with electrics and that build plan made myhead hurt

What's the big capacitor option ?