converting an old lathe to vfd drive

[Rambozo]

The downside to a 120 volt VFD is you will be limited to around 1HP. The heavy 10" is capable of more, but for most uses 1HP should be fine.

[TheGary]

The downside to a 120 volt VFD is you will be limited to around 1HP. The heavy 10" is capable of more, but for most uses 1HP should be fine.

I found a 110 volt vfd that is rated for 1 1/2 hp and For what I do that would be enough I think. My south bend has the motor in the cabinet so chips would not get in it real easy but with the permanent magnets in the treadmill motor I believe they would keep collecting metal chips until something shorts out. It might take a year or so but I think it would happen. The vfd I found is a cheap chinese made but I think I will gamble on it . Now I need to find a cheap 1 1/2 hp 3 phase motor.

[Rambozo]

I found a 110 volt vfd that is rated for 1 1/2 hp and For what I do that would be enough I think. My south bend has the motor in the cabinet so chips would not get in it real easy but with the permanent magnets in the treadmill motor I believe they would keep collecting metal chips until something shorts out. It might take a year or so but I think it would happen. The vfd I found is a cheap chinese made but I think I will gamble on it . Now I need to find a cheap 1 1/2 hp 3 phase motor.

You will need a special branch circuit to get to 1.5HP 3PH from 120V as the input current required is about 24 amps. 1HP is just under 17 amps so it can run on a standard 20 amp circuit. It's a lot easier to run with 240 input since that halves the current and reduces the wire size required. It all depends on how your shop is wired and what makes the most sense for your setup. You mentioned being able to move things around.
Finding a motor should be easy. 3 phase motors are dirt cheap because they are so simple. One great place to look for new ones is www.surpluscenter.com I'm sure you can find a TEFC motor for under $100 or even half that, if you look around a little.

[TheGary]

your right about the amps . I could install a light 220 circuit cheap since it could be 14 ga. If I go to 220v then I will look for a 2hp and install a 12 ga. circuit.

[Rambozo]

your right about the amps . I could install a light 220 circuit cheap since it could be 14 ga. If I go to 220v then I will look for a 2hp and install a 12 ga. circuit.

Sounds like the best plan.

[Paul Moir]

Automationdirect will sell you a well regarded 1hp drive for $134 w/ free shipping. A motor from them is similarly priced if you can't find one for free somewhere. The 2hp 1 phase pushes you up to a GS2 which is like $250, so that blows the budget. Treadmill motors are pretty popular on the minilathes but I think it would be pretty wimpy for a 10" SB, and DC speed controls seem to me to be pretty pricey for what they are.

That said, 2hp into a 10" lathe seems like a lot. I would think ~1hp would be plenty. My 10" is only 3/4 hp and I've never come close to stalling it, even in a crash! I do ~90% stainless and sometimes in pretty large diameters. I'll betcha 1/3hp was pretty horrid to use!

Nowadays, drives like the GS1 are super-simple to use. Plug in one side to your power, the other to your motor and set up a few basic parameters. Some of the cool things are that you can (often safely and allowed in the motor's datasheet) run your motor at higher than standard RPM, and mess with torque at lower RPM. Pretty much the only thing "ya gotta know" is not to hook the drive up backwards!

[TheGary]

Automationdirect will sell you a well regarded 1hp drive for $134 w/ free shipping. A motor from them is similarly priced if you can't find one for free somewhere. The 2hp 1 phase pushes you up to a GS2 which is like $250, so that blows the budget. Treadmill motors are pretty popular on the minilathes but I think it would be pretty wimpy for a 10" SB, and DC speed controls seem to me to be pretty pricey for what they are.

That said, 2hp into a 10" lathe seems like a lot. I would think ~1hp would be plenty. My 10" is only 3/4 hp and I've never come close to stalling it, even in a crash! I do ~90% stainless and sometimes in pretty large diameters. I'll betcha 1/3hp was pretty horrid to use!




Nowadays, drives like the GS1 are super-simple to use. Plug in one side to your power, the other to your motor and set up a few basic parameters. Some of the cool things are that you can (often safely and allowed in the motor's datasheet) run your motor at higher than standard RPM, and mess with torque at lower RPM. Pretty much the only thing "ya gotta know" is not to hook the drive up backwards!

Thanks for posting the web site. I will get a GS1 for a 1 hp motor. I am still trying to scrounge a 3 phase motor. I will not be getting an inverter duty motor. From my investigation it seems that if you stay with 240 volt 3 phase the insulation break down is not a common problem. It is when you are running 440-480 volt on a vfd that it is of the greatest concern. The other thing is cooling for low rpm running. I think I will incorporate a cooling fan into my motor compartment to help keep it cool at lower rpm. I seldom use the lathe for more than a few hours at a time anyway ( of course that might change when I get it working real good since it will be much more usable when I am done). I am not in a big hurry so it might take some time to get the motor as a freebe. If I do not find one in a few months then I will buy new. Its hard to make myself buy one when in the past I have seen dozens of them thrown in dumpsters at the job sites I have been on.