Originally Posted by
gicos
Yes, Galene, finally someone who sees the advantages. I let go a Simmons 2 HP with copper rotor for a great price because I couldn't seem to get any thoughts from those who know more. I asked in another forum how much I could expect to lose in power by hogging out a rotor for the bigger shaft (without getting into the squirrel cage) but it's near impossible to tell without just doing it. I figured I'd loose at least 1/2 HP or more, so starting with a 2 HP motor seemed about right to bring it down to 1 - 1 1/2 HP after modification. 1 1/2 HP we know is the limit for a VFD on 110V.
In a former life I was a mechanic, but never an electrical engineer. I'm no newbie to electricity but motor eddy, flux paths, and so on is its own discipline. I'm still with the idea, but it's going to have to be over a longer term than I wanted. You're absolutely right. Calculate the cost of headstock, pulleys, belts, mounting hardware, etc. and it becomes obvious that it's not so expensive to have an integrated solution. And mobility just doesn't mesh with the vernacular of a traditional lathe.
Victoro, yes the bearing are expensive, about $150 each. But, consider that many spindle bearings are over $100 each and it doesn't sound so crazy. The setup would definitely require a good VFD. Shrink the VFD down to where it can be bolted onto or integrated with the motor and you've really got portability. Judging from how fast things are progressing these days I don't think we're that far off from seeing integrated VFDs. The push for electric cars, motorcycles, and bicycles is really accelerating things. Other possibilities include DC motors. Look at the Astro motors that happily spin all day at 7500 rpm putting out 6-8 HP (for the affordable 3200 serioes). Yes, an expensive proposition, but it shows what can be done with high rpms and small motors. The case configuration wouldn't work with a hollow shaft, it's just proof of concept.