3 Phase Motor and VFD??

[Dan Cannon]

Hello All,
I am looking at a used lathe in great shape, but would surely want to convert it to VS rather quickly if I get it.
From my search on this and other sites, it seems that going to VFD with a 3phase AC motor is the preferred way of doing this. Treadmill motor is a much cheaper option, but I don't seem to get as much positive vibe from that.
Anyway, when looking at my options, it seems there is a huge range of prices for 1HP 3Phase motors. Is there something I'm missing, do I need anything particular? Some motors (on ebay) are around $65-$100, while others, seemingly simlar are well over $200. Why the differnece??
Does anyone know of a good source for a motor?
Also, I found a VFD for just over $100 at dealerselectric.com/mfg-subcat-item.asp?cID=28&scID=164&mID=-1. Anyone ever buy from them, seems like a good deal?

Finally, those really are the only 2 items I need, correct? It sounds like I might need someone much better versed in electronics to set it up for me, but as long as I know the components necessary to get VS.

Thanks for the insight. All of this will have to be considered before I pull the trigger on this lathe.
thanks!

Dan

[Greg Ketell]

There is currently a 2HP motor and VFD in the classifieds. $399 for both.

[Steve Harder]

Here's a link to my article that has some details on VFD and 3ph motors.

http://www.woodturnersresource.com/extras/projects/1624_vs/index.html

[Dennis Ford]

You are right about the wide range in motor prices. There are several factors at work here.
* nominal speed - slower speed motors cost more than 3600 rpm motors. It does matter, a 1 hp 1750 rpm motor running full speed will outperform a 2 hp 3500 rpm motor running at half speed (assuming that the motors are equally efficient etc.)
* enclosure type - TEFC (totally enclosed fan cooled) is more desirable and more expensive than ODP (open drip proof)
* frame size can vary and affect the price, you want one that will fit your machine.
* efficiency, service factor and brand also affect the price.

Be sure to get a motor that will run on the voltage that you have available, there some that only run on 480 and a few that only run on weird (to those in US) voltages.

[Dan Cannon]

Thanks for the input guys. I spent a lot of time looking over all the options last night, including what you all posted, and I get a feeling I'm in for more money than I had hoped for. I'd want to do it right, but it's hard to justify spending more on the VFD conversion than the lathe itself. We'll see, I'll let this one stew for a bit...
Thanks again,
Dan