We, being the home shop machinist, sometimes have three phase equipment in our shops that we would like to run. Being a "home shop", we typically have single phase power. That presents a problem for us, but there are options. The first is to change the motor for a single phase motor. This can be a bear as the frame sizes between motors are totally different, and there is usually considerable work needed to mate the new motor up to the existing mounting configuration. The motors can be expensive as well if you are buying a new one. The second option we have is to install a static phase converter. They work well, but have some drawbacks. The motor is only good for 2/3 of the rating, so if you have a 3HP motor, you are effectively getting 2HP out of it on a static converter. For our needs, this probably will do just fine. They range in price, but for a 1-3HP model, they run about $125.00. The third option is to install a rotary phase converter. This is a better option from the stand point of you are getting the full rating out of the motor rather than just two thirds. However, they come with a price tag. A 3HP model runs about $550.00. The fourth option is to get a VFD (Variable Frequency Drive) that has a built in phase converter. These unit have an advantage over the above option in that you can adjust the speed of the motor with the drive, yet retain the rating of the motor (to a certain degree). This is an attractive option due to the cost versus flexibility of the unit. One of these VFD units for a 3HP motor will run about $195.00. _________________________________________________ There is a story behind all of this, so here we go. I rescued a 10x50 mill from a business several years back. I won't get into details in this post, but the electrics were shot, and it needed some TLC. It has a three phase 3HP motor on it, and I had to have an option of powering it up in the home shop environment. I took the cheap road and bought a static phase converter. It worked fine. The mill ran great, and life was good. Except for one thing. When the motor was cold, it had a hard time starting. If it were cold enough, it wouldn't turn the motor over to start without some human assistance. Still, it was a workable situation, and after running the motor for a couple of minutes, it was good to go. Somewhere along the way, I heard of the VFDs with the built in phase converters. So, I looked into them, and found they were fairly inexpensive. I bit. The thought was that I would put in on the milling machine to see if there would be a benefit. It came in, and I installed it in a temporary fashion. Upon initial power up and a little bit of program setup, I cranked up the mill and played with it some. Well, I played with it for about a minute. That was all it took. I immediately made the installation permanent, and ordered a remote speed dial for it as well. The following week, everything was here and installed, and I now had a mill with a spindle that has infinite speed control from about 4 RPM to a little over 5000 RPM. Once this mod was done, it made it a totally different machine! With the fine speed control, finishes were better, the power is better, and there aren't any pesky belt adjustments needed for typical machining operations. And the cold motor troubles are history. Looking back, if I had it to do over again, the VFD would be the way I would convert the power. In my opinion, the flexibility of the speed control coupled with the relatively low cost is hard to beat!