Do we have any 3 phase guru's in here?

I got a turret lathe from a friend with a 10 hp 3 phase motor, and I need to get it running. After much research, I've decided that I just want an electrician to install/wire the whole thing up. I feel this is a time to hire the guy to do it right and not risk making a mistake myself.

At this size, a vfd is essentially out of the question. I already talked to an electrician that has some experience. I had thought that a 10hp vfd would work assuming that I don't need the full 10 horses the motor is capable of, but he said that just isn't going to work. I need at least 15, preferably 20hp converter. Any 20hp vfd costs as much as a new rotary converter anyways. Being a turret lathe, it has a few different gears to change speed. It's not infinitely adjustable like a vfd would be, but I feel confident that a rotary converter would last my lifetime whereas I'm not so sure on a vfd. In addition, I could probably use the single 20hp phase converter for every 3ph tool I'd ever want to buy rather than getting a new vfd for each individual machine as most people do.

So, my options are to buy a brand new rotary for around $1400, or build my own. I found a 20hp locally on craigslist for $300. I could buy a new 20hp panel for around $500. How janky is this? Do you think an electrician would have any issue doing this route?

I can't help but look at the cost of just getting this lathe turning and wonder why I don't buy an old southbend instead. It's a cool machine, but damn if it isn't over the top for me getting started in machining.


In case anyone is curious, this is pretty close to the lathe I have:
https://www.ebay.com/itm/Gisholt-Lathe-No-5-/262019805640

I see people asking big money for these all the time, but I don't see anyone getting close to this. But shit, I guess if someone wants to buy mine for $3k I'd be more than glad to sell it lol.

I think you need to get a 15 hp VFD
And it will run your 10 hp
No problem
I just purchased 3 15 hp for about $900.00
Each

I recently went through this process getting a 5hp 480v Hardinge HC-T running. For me, the answer ended up being a 10hp RPC from American Rotary to produce 3 phase 220v, fed into an 3 phase auto transformer from Maddox for 480v. This is all done as a sub panel with room for future circuits. 10hp was selected based on the idea that you want to have nominally twice the HP as the load and that was nearing the limitations of the panel supplying this when you figure worse case loading for the rest of the shop.

Total cost was higher then the lowest cost VFD/transformer I probably could have put together from Alibaba. The advantages are the RPC and tranny are from reputable American companies and produces fairly clean 3 phase 220 and 480, as well as whatever else I wanted to tap from the transformer. If I need to run any future 3 phase tools I'll be set with, at worst, another set of breakers and 240v 3 phase wiring.

Downsides, aside from the extra cost, is I miss the advantages of a programable VFD running the tools motor for variable speed and braking, making me dependent on the original CVT transmission and brake. While those work ok, it's not as precise as a VFD and requires some upkeep on my end. The RPC/transformer are not as efficient as a VFD and add to the background hum of the shop. As long as I'm not letting the RPC idle for long periods of time it's not a big added expense. Selling a 480v three phase tool in the future without a turn key VFD already wired and working may be a challenge.

The power feed, threading attachment, coolant pump and work light all run off cabinet power, so adapting those to run off the VFD's output would have been a pain and rewiring those extras to work on a single 220v leg may or may not have been a challenge, but either way I wasn't interested in taking it on.

I guess I need to clarify that this is going into a residential shop. 240V single phase input. All of the vfd's you listed are 3 phase input.

As others have stated, a VFD is certainly capable of running it.  I just set up a Rotary conversion.  Craigslist motor and an American Rotary panel.  I'm no electrician but honestly i didn't even look at never mind read the instructions.  They really do make them simple.   The idler motor noise is not bad, but it still gets annoying.  It will end up in a dog house outside of the garage soon.  

ETA:  you can always do a kick start, pull start or pony motor start idler to get you powered up on the cheap.  I've known guys who set one up 20 years ago and never upgraded.  

A rotary phase converter is pretty simple project if reading a little bit first isn't out of the question. This guy has a pretty nice step by step process on building one

Most VFDs can be run on single phase input even if not spec'd for it but they must be derated bc the DC buss isn't sized for the higher current single phase input will create.

Your electrician is correct that you need a 15 hp minimum, 20 hp recommended. Unfortunately you can't undersize based on the work/load very much because the motor & gear-train in the headstock still take quite a bit to get it all turning.

Pretty easy to build a rotary and easy to get them in phase so they run smoother. I built several 30 years ago. We made them using start caps, appropriately sized mechanical relays and a couple of switches, along with a properly sized idler motor. Some of them I used the machine motor as an idler and used run caps to balance the load. I might make one up for s-n-g. The start caps we used were 8mfd per motor hp and the run caps were 8mfd per motor fl amps. We would provide the 3rd leg necessary for starting via a separate relay fed by the primary relay and activated via a momentary switch which fed the start caps.
Back then we could buy  3ph motors for $3/lb out of a scrap yard. You can also balance your load by running it througha transformer, which your machine should have.

If you plan on buying more equipment, an oversized rpc is the way to go.  I have a 7.5hp american rotary that was hardwired to the lathe and mill.  I added a few recepticals that i could plug my tablesaw, radial arm drill, and other tools into as needed.  I also have a 15hp american rotary that came with my cnc mill.  

When i get around to building a shop, I plan on a 20-30hp rpc with its own panel and permanent wiring branching off from there as if power came from the pole.

Everyone told me that a RPC will be loud...  I forget mine is running sometimes.  Its not loud at all.  Its only 2 or 3 hp, but it is not loud at all.  I called a local motor place and told them what I needed, and they built it larger than what i needed.  Really simple set up.

Bigger = louder

The shop my dad bought his Powerturn lathes from has a shed out back with a 100 hp and 60 hp synced up. Dad has a 70 hp. They aren't "loud" per se, but they do have a constant droning sound that can get annoying if you're always trying to talk over it. Many shops put them in a shed out back but it's not a requirement.