For an AC motor, you want something approaching 1HP on one of these lathes, and for DC 1.2 would be ideal. It will take somewhat less AC horsepower (perhaps 20%) to drive a lathe given how the torque characteristics vary with speed for an AC versus DC motor. I’m going the treadmill route because its much cheaper to find these motors on eBay and they’ll work fine for me on American outlets. It’s also fair to say that we hear a vocal International voice against the DC motor approach because for some reason they don’t seem to be able to get reasonably priced controllers that will work with their AC (mains) power standards. It’s fair to say the latter is closer to industry practice. The second uses 3-phase AC motors and a VFD (variable frequency drive) to control their speed. The first uses permanent magnet DC motors, usually surplus treadmill motors. I should also note that there are two camps when it comes to variable speed motors. Be sure to read their web articles too and you’ll learn a lot.
I didn’t invent this mod, I’ve largely copied the work of others. Highly recommended!īefore I get too much further, let me say I was really inspired by all the lathe modification articles I read. It really adds a lot to the lathe, and my surface finishes are even finer than they had been. Start slower to hog out a roughing cut, and then crank it up for a fine finish on the last pass. If chatter sets in, change speeds and it goes away. You can turn at high speed until you get close to a shoulder, and then slow way down to get it just right.
Having now completed the modification, I have to say that it is fabulous! Being able to change speed at the twist of the dial is a dream come true. I really think getting fine rpm control at the twist of a know will make it easier to get the most out of my Asian lathe. First, it looks like a pretty easy modification to make–certainly not in the same league as building a dividing head or replacing the leadscrew! Second, there is a lot of bang for the buck. Reading over the various potential modifications, I decided the DC motor needed to come fairly early in the process for several reasons. Lathe Modification: Variable Speed Treadmill DC Motor