OK, so just Googled KBAC VFD and this popped up! Well I can't figure out how to get a screenshot to work on this but here is the search.
https://www.google.com/search?q=KBA...e..69i57.1884289j0j7&sourceid=chrome&ie=UTF-8
So on that search, there is 5 different units across the top and five different prices and more if you click on the arrow on the right side. So what are we looking at here??? What is recommended???
The KB drives come in two basic flavors: 3-phase input and Single Phase input. For we mere mortals, our houses only have single phase. So in the Single Phase offerings, you can choose to run your VFD off 110 or 220. Using 110VAC input limits you to 1Hp I believe, but it may be 1.5HP The 220VAC input single phase models go up to 3HP if I'm not mistaken. So, all that determines the model number you're after.
Also I got to ask what is the big advantage to a variable frequency AC drive?? I mean I may see some of the advantage especially with handle material but how much can you slow down grinding steel till you aren't really cutting any more!!
Two big things:
1. It allows you to change motor speed on the fly. All you have to do is turn the knob to speed up or slow down. This doesn't sound like a big deal until you have it, then all of a sudden you get control over your grinds like you never imagined. You can get past splice bump for the most part, you can control your heat better, you can speed up to hog off material and then slow down, which is awesome when you are doing handle shaping.
2. High torque at slow speeds. A VFD can run your motor at slow speed, but give it all the juice it needs for constant torque. If you've ever used a DC drive, you probably noticed that as the motor slows down it loses power. A VFD solves that problem. You get full torque across the speed range.
Obviously, you don't need a VFD to make knives. But man is it nice. As soon as my drill press motor goes out that will get a 3ph motor so I can run it off my grinder's VFD. Ditto for my bandsaw.