Remotor or Rotary Phase Converter

Hi

I will be taking delivery of a replacement lathe shortly. It is 3 phase with a variable speed belt drive. I would like your thoughts on a rotary phase converter or remotor with a single phase motor. The cost is the same for ether option.

Thanks

Tim

Just get the motor
The draw back to rotary phase converter it will run all day cost money to run just rotary phase converter

Have try both ways

Dave

Why not use a Variable Frequency Drive (VFD)? Many are available as single phase input and 3 phase output, with the added bonus of variable speed (frequency). As long as the motor is a 220 to 250V motor you should be able to find a VFD to drive it.

I've got a 3hp on on my mill and a 1 1/2 hp on my lathe - absolutely love them. Single phase, 60Hz 220VAC in, 3 phase 220V out (15-400Hz)
Mike

Check Surplus Center, they had the converters pretty cheap, and sometimes they have pretty good prices on electric motors

I'd choose VFD unless you have more than, say, four machines needing 3-phase conversion. The VFD gives you motor protection, speed control, logic, and quietness all in one package. I have four VFDs in my shop. The manual mill has two: one for the spindle motor and one for the feed motor. The Chipmaster lathe has one, and the bandsaw has one. Only the bandsaw regularly uses the variable-speed capabilities of the VFD. The other machines still have functional mechanical variators. Nonetheless, I don't need to worry about motor starter heaters or relay logic, and I could easily integrate the motor controls into the existing machine pushbuttons, eStops, etc. I do use the VFD speed control occasionally to lower the spindle speed to a crawl, such as when winding springs.

fltenwheeler said:

Hi

I will be taking delivery of a replacement lathe shortly. It is 3 phase with a variable speed belt drive. I would like your thoughts on a rotary phase converter or remotor with a single phase motor. The cost is the same for ether option.

Thanks

Tim

Click to expand...

What size three phase motor? Generally below 3HP Variable Frequency Drives (VFD's) are very economical for converting old equipment. Now you are indicating a variable speed belt drive which is useful even with a VFD. Even with a good VFD and motor it is still useful to be able to do belt reduction to get more torque.

Wizard69 said:

What size three phase motor? Generally below 3HP Variable Frequency Drives (VFD's) are very economical for converting old equipment. Now you are indicating a variable speed belt drive which is useful even with a VFD. Even with a good VFD and motor it is still useful to be able to do belt reduction to get more torque.

Click to expand...

It is a 2HP on a Rockwell 14"x30" lathe.

Tim

Depending on mount you can get a single phase motor for about the same price as a phase converter, the thing to remember is your motor will only make about 2/3 of its hyorsepower, if possible I would remotor

fltenwheeler said:

It is a 2HP on a Rockwell 14"x30" lathe.

Tim

Click to expand...

At 2 HP you should be able to find a cost effective VFD. Unless you go the DIY route, a rotary phase inverters isn't exactly cheap. The only issue you might run into is that drive will likely require 220 VAC input you should be able to find a drive that can take single phase in for that HP range. Automation direct for example has a drive, GS2, that starts at around $250.

There are additional expenses such as a panel box, wire, fuses and etc. Those are expenses though that any solution requires. You could look for a drive that comes with an enclosure which obviously costs more

I just wanted to point out VFD because for whatever reason people don't seem to know that they are very cost effective these days. Below 1HP they compete with the old cheap DC drives very well, often the "better" solution.

Beyond all of the above VFD's offer features that aren't available with rotary converters. This includes soft start, variable speed, electronic reversing (some models), and other features.

Ultimately the choice is yours. VFD's are just one of your options but they do seem to be overlooked often by people buying industrial equipment.

Hi

I have both systems. I have used VFD's for over ten years. I have them on two mills a 1HP and 2HP. I have one on a 2HP 12" lathe. I put one on my 7.5HP air compressor, it is set for a soft start and only run at about 1/2 the RPM so minimal noise. The variable speed feature is real nice. As for the power reduction I have really not noticed it, on the 12" lathe I took a cut that snapped a 3/8" HSS cutter as an experiment. Given I would never take cuts like that anyway for me the power reduction is a none issue. I also have a 10HP commercial rotary that powers any thing that has two motors ie Norton Grinder, or two speed motors ie my drill press.

So from my experience I needed multiple solutions. Good Luck setting everything up and making chips.

Bob

Bob

I have been running on an idler motor started by capacitors similar to:

http://www.k3pgp.org/3phconv.htm

The parts for the capacitor start circuit are under $100.

Old used 3 phase motors are cheap. The old cast iron frame motors in the 3 HP range run in the $25 range in my area.

I just start the idler motor with the capacitor circuit and then have the three phase circuit wired to various receptacle around the shop. At this point I am mainly running a 2 HP lathe and a 1 1/2 HP mill. The idler motor draws almost no current when just idling and when I start the other machines it is instant start. Now I am running just my home hobby retirement shop but I ran a lot more when I owned and operated a metal fabricating shop for several years before I could get 3 phase power.

I made a capacitor start box as above using banks of capacitors hooked to switches so that I could use the same converter for various horse powers. I probably made and sold a dozen of them. Actually it is not necessary to have the banks of capacitors. Just get an idler motor larger than your largest machine motor and everything starts and runs just fine.

For a home shop it is possible to just run an idler motor with a sheave on the shaft and kick it over to get it started. Once it is started it keeps running. I did that on my home shop when I was just using it occasionally before I retired.

As an interesting side note. When I started the fabricating shop 3 phase power was about 1/2 mile away and to run the three phase to the shop would cost me several thousand dollars. Finally when I had several employees it was getting to be kind of a problem so I looked into how much it was going to cost me to run in the three phase. I found out that they could upgrade my existing service for free. Had I know that I would have upgraded the week after I put in the single phase.

TRACKWELDER said:

Depending on mount you can get a single phase motor for about the same price as a phase converter, the thing to remember is your motor will only make about 2/3 of its hyorsepower, if possible I would remotor

Click to expand...

That is not true. Source?

rklopp said:

That is not true. Source?

Click to expand...

It all depends upon how you decode the sentence. I think what he is saying is that you loose horse power when running off a simple 3 phase rotary converter. This is generally true.

rklopp said:

I'd choose VFD unless you have more than, say, four machines needing 3-phase conversion. The VFD gives you motor protection, speed control, logic, and quietness all in one package. I have four VFDs in my shop. The manual mill has two: one for the spindle motor and one for the feed motor. The Chipmaster lathe has one, and the bandsaw has one. Only the bandsaw regularly uses the variable-speed capabilities of the VFD. The other machines still have functional mechanical variators. Nonetheless, I don't need to worry about motor starter heaters or relay logic, and I could easily integrate the motor controls into the existing machine pushbuttons, eStops, etc. I do use the VFD speed control occasionally to lower the spindle speed to a crawl, such as when winding springs.

Click to expand...

I am in the same boat with a 575volt chipmaster. My intention was to connect a 3hp vfd to the line input of the control box at the back and change out the motor to the same voltage as my 230v single phase service. I'm not up on vfds and what you can and cannot connect to them, but I was told that all the vfds want to see on their o/p is a direct connection to the motor, nothing else! I really don't want to hack up the electrics or bypass them. rklopp, can you tell me exactly what you have setup on your chipmaster? Are you running all of the original equipment.

Build a rotor phase simple
When my shop I did both

Dave

I have a 240-V VFD connected directly to the original Brooks Crompton motor, with no disconnect between the VFD and motor. The rotary forward/off/reverse switch controlled by the red ball handle above the headstock is wired to the VFD remote control inputs. The coolant pump motor is abandoned in place. The worklamp is powered separately via a normal wall receptacle.

I have two mills that were originally 575-V. On one, I removed the 575-V motors and replaced them with 240-V 3-phase motors driven by separate VFDs. On the other, I built a 575-V step-up transformer system to power the mill from my 240-V phase converter. That mill has kept its original electrical system.

Unless you foresee more 575-V machines or have a strong yearning to keep the Chipmaster all-original, if I were in your shoes, I'd swap the motor to a 240-V, 3-HP, 3-phase, 4-pole motor and drive it with a 240-V VFD wired directly to the motor, and reconfigure the switches to control the VFD. YMMV.

No one mentioned the fact that on (especially belt) lathes, you get a better finish with 3 phase.

If the 3 phase motor in question is not dual voltage you can still go the VFD path. There are units that take 220/230V single phase in and supply 380V 3 phase out. You do need to get double the wattage though. Eg 1HP motor needs 1.4kW or better VFD.

The VFD path definitely has many advantages as other posters have pointed out.

Ironmanaz said:

No one mentioned the fact that on (especially belt) lathes, you get a better finish with 3 phase.

Click to expand...

This is an old wives’ tale, Snopes-worthy.

I have built many rotary converters, they can be simple or they can be more involved.
Another solution for you to consider, if you are in the states. There are a couple of outfits selling a unit that you just ad in line of your wiring.
One unit called Phazpak, lots of info online. They are in Indiana. very simple to install.
Wire the motor for your voltage and power it up.
Or you can use the phazpak on a idler motor and power multiple motors on other equipment.