Am I in over my head? Machine ID

While not difficult, any motor swap is likely going to involve fabricating some sort of adapter plate as your replacement motor will be smaller than the previous motor. If you can do that just once it'll save you some work. I and others here have had good luck with TECO VFDs. Did you get the pulley from the old motor?
Yes the original pully was with it.
The problem with the VFD is you need to modify the circuitry in the lathe itself since VFD’s need to be directly connected to their loads (motor) without any switches in between.

It’s an awesome setup @mksj can help with it but a static converter is cheap and you can just hook it up to the main power input for the whole machine and start using it.

John
I did some reading on North American Phase Converters website. It states that "A North America static phase converter will only run motor loads. Because it does not produce a constant 3rd leg of power, a static converter will not run a resistive or inductive load." Looking at the lathes electrical drawing it shows 3 phase incoming power going to the main motor and the coolant sump pump. A transformer then reduces voltage to 110V to power the relays and other circuitry. If I were to use a static converter, the transformer would need to be removed from the circuit and 110V power supplied to the remaining circuit, and I would be using the static phase converter strictly for the two motors. I do have a local "scrap yard" that buys surplus industrial electrical equipment. He has 3 phase motors fairly cheap, North American sells just the control panel for their rotary phase converters and the end user supplies the idler motor. This would be an affordable option.

Question: What would be the turning limits of say a 3, 5, and 7.5HP motor? Is it dictated by stock diameter, depth of cut or mass?
At this point the largest project I have planned is a 12"x2" round bending die for building roll cages.

Is the chip pan around anywhere? They slide in and out like a drawer.
Yes it came with a slide in chip pan, and a rear mounted chip catcher, which unfortunately was bent by the forklift operator who loaded it on my trailer :(
 
You can run the transformer without problem IF you are careful to hook it up to the two legs that come directly from the utility. So your three phase is actually made up of 3 wires, two from the utility (call those wires 1 & 2) and one from the phase converter (wire 3) often called the "manufactured leg". As long as you make sure your transformer is on wires 1 & 2 you can run the transformer without concerns, as it always sees the utility voltage This takes a little careful wiring but is how most of these setups are handled.

Machinery's handbook will give you detailed formulas, but 5 HP is a LOT of power for a lathe. Power is determined by
  • Type of cutting tool, which amongst other things dictates cutting speed (SFPM). Higher SFPM means higher horsepower, all else being equal.
  • Related to type of cutting tool is how sharp that tool is. Dull tools require more HP
  • Type of material - stainless teel, or super hard alloys are tougher, more HP
  • Depth of cut and feed rate - deeper cut and higher feed both require more HP
You'd think diameter would factor in. But cutting speed is a linear equivalaent. So at larger diameters, you spin the object at less RPM to get the same cutting speed. With the gearing, you get more torque at lower RPM (effectively like downshifting in a car). So the diameter is a wash.

Generally though, when comparing these level of horsepower 3 vs 5 vs 7.5, you're talking mostly about how quickly you can rough a piece down to size. Hobbiest generally prefer not to get too aggressive about roughing, if for no other reason than that the large, very hot chips are painful if not outright dangerous. I run a 4000 lb Monarch 12"CK (14 x 30 swing) on a 3HP motor. At the time I couldn't find a TECO that went to 5 HP on single phase in. And 5HP on single phase requires more than a 20A 220V circuit, which will run 3HP if you're talking about VFDs. (Rotary Phase Converters are slightly more power hungry, depending on sizing.) But I haven't regretted the lack of HP. Since the Monarch only turns at up to 1000RPM, and yours will spin faster, a 5HP might be worthwhile. Unrelated, but if you're running a lathe that is *not* geared and trying to drive it with a VFD, you would need more HP, but with a geared lathe, you can shift speeds and get plenty of torque.

My first lathe, a 10 x 22, was 1HP VFD drive and was plenty of HP for starting out/learning.

A 10HP idler rotary phase converter will do a good job of driving a 5HP lathe motor, and give you plenty of options for future 3phase machines.
 
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What are your thoughts on using a VFD to strictly convert 1 to 3 phase at 60hz? I'm researching static rotary phase converters at the moment.

To me, a VFD seems overkill for a fixed-frequency drive....or where there are other parallel motors (feed, coolant pumps) that need a constant frequency.

Here's a thread where I initially suggested a VFD, but was schooled (politely and rightly) about static phase converters.
It a good read with a link to a great video.

-brino
 
To me, a VFD seems overkill for a fixed-frequency drive....or where there are other parallel motors (feed, coolant pumps) that need a constant frequency.

Here's a thread where I initially suggested a VFD, but was schooled (politely and rightly) about static phase converters.
It a good read with a link to a great video.

-brino
Missing link?!
 
After some reading I realize that a VFD is not best for this purpose. Plus the band saw I purchased along with the lathe is also 3 phase.
This has me leaning towards a rotary phase so that I can power both (and any future purchases) without rewiring and replacing motors.
 
The inductive loads that North American is talking about are things like ovens. You will have no problem running a lathe off their static converters (at least I don't)....

If you have two or more 3 phase machines it's up to you to figure out what's better. I have my lathe wired so there's an on/off push button that turns on the static converter, folks on here with static converters sometimes need to wire some sort of pilot light so they don't accidentally leave it going because they do consume power even when nothing's drawing a load.

Either way it will be much easier than wiring in a VFD, although I do have one on my Seneca Falls. But that only has to run the motor, there's no other electrical on it.

John
 
If one has multiple 3 phase machines, is it possible to wire them together, so idling one or more, could make it act as a rotary phase convertor for another?
 
I wish he would have measured the voltages with the load motor running, I may do some experimenting once I determin what capacitor size is needed.
The inductive loads that North American is talking about are things like ovens. You will have no problem running a lathe off their static converters (at least I don't)....
A transformer is an inductive load, however I studied the electrical drawings some more and it looks like it takes power from Line R & T. If I wire it so that R&T are fed from L1 & 2 that comes directly from the wall it should work.

The control cabinet is a little busy...

Screenshot_20210525-080118_Drive.jpg



Control Cabinet.jpg
 
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