Posted by Sherman in Idaho [72.47.153.61] on Thursday, February 12, 2015 at 20:07:47 :
In Reply to: Re: Look on publicsurplus.com posted by Randy On Long Island [63.117.245.30] on Thursday, February 12, 2015 at 19:19:09 :
Actually, that's really the thing to look FOR. Most home-shop guys won't buy a 3-phase machine, so they sell cheap, but if you've got any kind of a bone yard of motors, or any sort of surplus place nearby, you can pick up a suitable single-phase motor for much less than the difference in price between a single-phase and 3-phase machine at auction. A drill press rarely needs more than a 1 horse motor, and every one I've seen had a standard motor mount (not a custom job like the old Bridgeport milling machines, for example). Also, it's not hard, if you're handy with electricity, to make a capacitor box that will start a 3-phase motor and then run it on single-phase. It will have less power but it's often adequate. When you do that, you lose the smoothness of torque that a 3-phase motor provides, but it's no worse than any other single-phase motor.
Lastly, VFDs have gotten so cheap these days that you only have to put a portion of the money you saved on the machine towards a VFD. A 1 horse VFD is only about $140, and that not only gives you 3 phases from a 1, but lets you dial down the speed without having to change the belt pulley, and it includes lots of protection against various faults and overloads. Unlike changing the belts, you don't get increased torque at lower speeds with a VFD, but usually that's okay.
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