Re-powering a Hardinge HC

I have a Hardinge CHNC I and if I'm not mistaken the HC is the same basic lathe? Do you have a photo of the machine? My CHNC does 6000 RPM so depending on the motor and VFD you select and the RPM you want that would dictate the ratio needed. For example if you need 6000 RPM and you have a motor that can take 120 freq and go say double the rated speed of 1800 that would give you 3600 RPM so almost 2 to 1 ratio to get 6000 but that just depends on your needs.

A 5 HP motor would require 3 phase power either from the grid or from a rotary phase converter which is easy to make but VFD's don't like getting power from a RPC IIRC.

JT

I would suggest that 6000 rpm is so rarely useful on a lathe that you might want to gear for slower to get a larger cut on larger work.

My lathe is rated for 3000 rpm but the macros that I generally run top out at 2500 (inherited from a previous lathe) and this bothers me so little that I have not changed it.

If you make a _lot_ of tiny parts then perhaps it makes sense to gear for 6000, but even with carbide tooling 6000rpm is only needed on parts smaller than 4mm diameter (in steel)