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Posted by David Sherman [24.32.202.83] on Saturday, April 17, 2010 at 14:50:06 :
In Reply to: Re: OT New/Old purchase posted by Kaegi [24.113.81.122] on Saturday, April 17, 2010 at 13:03:58 :
Correct. If you only need 1 HP or less, you can get the 120V version. I would recommend using 240 for 1 HP, though, just because of the voltage drop in the wires. It's safe either way, but a 1 HP motor is definitely peppier when run on 240V. They're usually switchable internally. Drill presses are usually only 1/2 HP, though, and there's no noticeable difference in performance between 120 and 240 with them. I think I'll try one of those VFDs on my old Craftsman drill press before I use it on anything else, because that's where the variable speed and reversibility would be nice.
VFDs do not give you an increase in torque at lower speeds, like pulleys do, though. They're constant-torque devices rather than constant-horsepower devices. I have another drill press that I keep the pulleys set for very slow speeds, though, for drilling big holes in metal, so I use the Craftsman for smaller or more precise stuff where it has plenty of power.
Remember, all VFDs must drive 3-phase motors. The input can be single phase, but the output is always 3 phase.
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