I've completed the conversion of my lathe from 3 phase power supply to using a single-to-three phase VFD and as a reference for others thought I'd post some basics. With much appreciated assistance from MotionGuru, I was able to retain the Whacheon's original Forward/Reverse lever (switch) and also the foot brake function.
Externally, the lathe looks the same as before. I was able to make all relay necessary changes inside the original control box. Of course, the VFD is mounted away from the lathe on the wall, but the lathe itself looks the same.
The lathe came with a very nicely wired and labelled box that contained the usual Fwd and Rev contactors as well as a control relay. In basic terms, I disconnected the contactors and replaced them with 4PDT 'ice cube' relays. At first, I used the original control relay and it worked fine but the relay had a good hum to it...so I used a third ice cube relay in its place and it is stone quiet now.
I could have 'hollowed out' the control box easily enough, but I chose to leave all the original relays in place in case someone ever wants to return the lathe to normal 3 phase.
The lathe runs off 240v. but the controls are all 120v. I used the original Power switch to handle the controls (as original) and the original coolant pump switch to turn the VFD on/off by means of a magnetic contactor. I don't use coolant so the pump switch was available....
There are four separate cables running to/from the lathe's control box...the 240v VFD feed, the 120v control (and DRO) power, the magnetic contactor leads, and the VFD 24vDC wiring. They look a little messier than I like but that is for a reason...the VFD feed and control cables are kept away from all others.
The VFD is a WEG CFW700 which thus far has performed flawlessly. It has a ton of programmable features. I have it set to accelerate in 6 seconds and coast to a stop. I did have it set to decel in 6 seconds but the motor would be 'in competition' with the foot brake. I'm going to look into using an encoder to stop the lathe, though, as I can set it up to always stop with my chuck key in the same position.
The photos show the relays in the control box and the lathe up and running with the VFD in the background. You can see taped to the wall are all the VFD manual programming pages!
Externally, the lathe looks the same as before. I was able to make all relay necessary changes inside the original control box. Of course, the VFD is mounted away from the lathe on the wall, but the lathe itself looks the same.
The lathe came with a very nicely wired and labelled box that contained the usual Fwd and Rev contactors as well as a control relay. In basic terms, I disconnected the contactors and replaced them with 4PDT 'ice cube' relays. At first, I used the original control relay and it worked fine but the relay had a good hum to it...so I used a third ice cube relay in its place and it is stone quiet now.
I could have 'hollowed out' the control box easily enough, but I chose to leave all the original relays in place in case someone ever wants to return the lathe to normal 3 phase.
The lathe runs off 240v. but the controls are all 120v. I used the original Power switch to handle the controls (as original) and the original coolant pump switch to turn the VFD on/off by means of a magnetic contactor. I don't use coolant so the pump switch was available....
There are four separate cables running to/from the lathe's control box...the 240v VFD feed, the 120v control (and DRO) power, the magnetic contactor leads, and the VFD 24vDC wiring. They look a little messier than I like but that is for a reason...the VFD feed and control cables are kept away from all others.
The VFD is a WEG CFW700 which thus far has performed flawlessly. It has a ton of programmable features. I have it set to accelerate in 6 seconds and coast to a stop. I did have it set to decel in 6 seconds but the motor would be 'in competition' with the foot brake. I'm going to look into using an encoder to stop the lathe, though, as I can set it up to always stop with my chuck key in the same position.
The photos show the relays in the control box and the lathe up and running with the VFD in the background. You can see taped to the wall are all the VFD manual programming pages!