Peter covered your basic question extremely well, as always. Just to offer some additional points for thought, I often hear the HLV-H machines rated at 1.5 hp, but a careful reading of the manual and wiring diagram on mine indicates ratings of 1 hp in high range and 1/2 hp in the low speed range. That assumes full torque loading, which only occurs briefly when you are hogging a 10" stainless steel ring at a really aggressive feed rate.
I think the mixup occurs because the motor manufacturer (GE for mine) puts 1/.5hp on the motor nameplate. A 1 hp VFD runs mine quite well, and that takes into account the expected derating since it is a nominal 3 phase input model.
The wiring diagram contained in the door of the "electrics" shows the coolant pump to be rated at 1/10 hp. The speed change motor is 1/20 hp, and the power feed motor is 1/15 hp. BTW, after much research, there is no way I would ever try to swap one of the spindle drive motors for a general purpose motor with a lower voltage. The fact that they are balanced to .0005 ounces is one of the carefully planned contributors to the mirror finish possible with the Hardinge lathe.
If you don't wish to 'build it yourself', an equally viable option is picking up a 440v VFD like I did. There is a company selling brand new GE AV-300i 440v VFDs on the bay at the moment for about the same order of magnitude you can spend on capacitors and other parts to put together a rotary unless you buy used parts. I just bought a 2hp model at a "buy it now" price of $90 simply to have a spare, though I think the current price is somewhere around $165. These units sell about ten times that from GE... They are 3 phase input, so some derating is necessary. The seller asked if I wanted some more, as he had about twenty to sell, and sounds like he would negotiate. The 440/480v units typically go quite reasonably throughout the year, though.
I initially picked up a 3kVA 240/480v transformer off the bay for $25, but have since found a 2 kVA 'lighting' transformer for $10 at a hamfest, so they are available quite reasonably. I ended up selling my rotary converter recently - the sound of silence is delightful!
There are some other advantages in using a VFD. One is its ability to provide a virtual back gear for the Hardinge. If you need to turn something *really* slowly, it's a cinch with the VFD. You can get 30 rpm with a 15 Hz drive frequency, though I would be careful about running it that slow for more than a brief period with the unventilated drive motor. (That lack of a back gear has been a perennial complaint about the Hardinge.) Another advantage (at least with modern units like the GE AV-300 and AF-300) is the delicate treatment of the drive motor they offer. They constantly monitor the operating parameters of the motor and treat it with kid gloves, shutting it down at the slightest deviation from normal operating parameters. Hard to get that from a rotary converter, and given replacement cost, I'd like that motor to be around for a looooong time.
Best regards,
Mike
