I just did it recently..... hooked up two 3hp grinder motors to a single KBAC 29D. I've not gotten around to a tutorial yet, but it's a fairly easy thing to do. The toughest part was to find was a 9 pole toggle switch, which I never found, but purchased this one: http://www.surpluscenter.com/Electrical/Switches/Toggle-Switches/4PDT-CO-TOGGLE-SWITCH-15-AMPS-11-3221.axd . (its a 12 pole switch, but you only use 9 of the poles for this application)

The thing I'm not sure about is doing it with different HP motors....both the motors I have hooked up are identical Leeson 3hp motors. I would ASSUME that as long as the VFD output is correct for the LARGEST size motor being used, another, lesser HP SHOULD be OK to be hooked to the other side of the toggle..... BUT I CANNOT BE SURE, AND MAKE NO GUARANTEES!

I'll try to explain in words how I did it. On the VFD there is a spot for a forward/reverse switch, which had a rubber plug in it. I took out the rubber plug, and placed the above toggle switch in it's place. On the back of the toggle switch there are 12 poles....you only use 9 of them. On the inside of the VFD you have the power coming into it from the wall/wiring, and there are three terminals/wires where the power goes out to the motor the VFD is running. I wired those three wires into three poles in the middle/back of the toggle switch. I kept track of the wires as I connected them, and then simple used three poles on one side of the back of the toggle to one motor, and three poles on the other side/back of the toggle to the other motor. I had to rotate the toggle switch 180 degrees in the VFD hole when I was finished....because the switch wasn't pointing towards the motor it was powering....just a DUH on my part.

I learned something very quickly....YOU MUST ALLOW ONE MOTOR TO COMPLETELY STOP TURNING BEFORE SWITCHING THE POWER TO THE OTHER MOTOR. OTHERWISE YOU WILL NOT ONLY WRECK THE TOGGLE, BUT YOU WILL ALSO DAMAGE THE INTERNALS OF THE VFD. I didn't do this the first time, and had to put in a new toggle switch.....nothing bad happened, just the toggle would not longer work to that particular position. (good thing I ordered two of them) <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

I'll see about getting a tutorial built and put up on my website soon. Pics will make it very clear.

I did it when I got my belt grinder I won't talk about my previous belt grinder the disc and belt grinder are both 1hp . I think that toggle switch Ed showed might be the same one I used I have a remote potentiometer because I needed to enclose my vfd. I'm happy with the setup sometime I will break down and get a more powerful grinder motor. I should have used a bigger box (alot of wires) for the toggle switch.

Gilbert

Just wanted to share.....since I just did this mod, I decided to put up a webpage on my site with details (sorta) of how I did it....

http://www.caffreyknives.net/1_VFD_2_Motors.html

Thanks Ed and Gilbert! Great info... I knew it could be done <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//cool.gi f' class='bbc_emoticon' alt='B)' />

Ed

I run my surface grinder and my 2x72 grinder with the same VFD. I went the cheap and easy way. I simply put a female outlet in my vfd panel and plugs on my cords. I simply plug in what I want to use. the nice thing about this is that I am not limited to 2 pieces of equipment. I use heavy duty twist lock plugs.

Brian

Another very cool idea! Thanks Brian!

This is great info-thanks for posting how you guys did it. I've wondered myself how to use mine for another machine at some point. For now, my disc grinder runs off of my KMG, so no need yet to run something else....yet.... <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

Jeremy