Renovating a Hardinge HLV-H

[aafradio]

I had to finish the worklight before I could post these :)

What a difference a day makes... (with apologies to Dinah Washington...)

I'm bidding on a couple of low power (100W) VFDs to run the coolant pump and speed change motors at the moment, with the intention to completely rewire the control box.

Actually, the spindle motor VFD will also run the small motors quite well without complaint, Bill. I don't know how you intend to use your VFD, but I use mine 99% of the time to generate 60Hz (50 Hz in your case.) The remaining 1% is for a virtual backgear for slow threading or large faceplate work in stainless or other tough steels at 25-30Hz. That big super balanced motor is on a 5 hp frame and won't take overspeeding lightly.

The plan is to use the interlocked pair of contactors (currently used to control the speed adjust motor) as a new speed selector relay. This new relay pair will only change speed (thus disconnecting the VFD) when the VFD is stopped.

I may have misunderstood the logic you described, but I believe I might rethink that approach. You absolutely want the ability to raise or lower spindle speed while the tool tip is cutting! I can't count the number of times just a small change in speed has stopped tool system resonance (skreeeeech) and resulting finish problems when turning a part or threading. I wouldn't give up that unique capability that Hardinge designed into the lathe for a thousand bucks.

Here's a suggestion - just bypass the control transformer (feeding it from straight 415v), and hook up the VFD feeding everything else and give it a try. You won't have to change anything that way except the wires to the control transformer. Leave the high/low speed lever in the position you will use most of the time. Use a separate on/off pushbutton for the VFD like this one:

Try it...you'll like it...