Millrite with 3/4 HP 3 Phase

[mgraham1930]

I am looking for some advise on my Millrite. I do not know much about electrical but my Millrite has a three phase 3/4 HP motor and I only have 110 V house power where I want to use it. Is it possible to somehow use the current motor or to replace the three phase with a single phase 110V. Would I be able to find a 110V motor with the same mounting pattern and shaft length and diameter.
Any recommendations or advise would be greatly appreciated.
Thanks
mgraham1930

 

[JST]

A picture would help with the motor replacement questions... most not having a Millrite won't know what type/style the motor is. I assume it is a C-face that mounts by a flange. Those are not so common in 120V motors, but do exist. May not be particularly cheap.

There are other options....

You could add a step-up transformer, and use a "static phase converter". It allows about 60% power, but you likely are not going to run that machine hard, at least for a while.

You can also get a VFD that takes 120V input and produces 230V 3 phase output. Probably not super expensive, might be comparable to a 120V motor, depending on the mounting required.

Those are the easier options other than a new motor.

 

[dalmatiangirl61]

Can you get 220v single phase to it?

 

[memphisjed]

Vfd is easiest solution. Bonus you get speed control. Not the cheapest or most feature rich, but a solid choice for simplicity and control.

https://www.amazon.com/KB-Electronics-KBMA-24D-Enclosure-Frequency/dp/B01AOCJT0K

 

[wood2steel]

I agree with Dalmatian, if you were able to get that machine in its place you can surely get a 220 v line to that area; add a VFD and you are good to go. Thats a nice mill. Get her running. Don't dare mess with changing the motor. Too many new issues to deal with

 

[memphisjed]

Why the need for 220? It is a 3/4 horse motor, plenty of 110 vfds in the sub horse range. 110 single phase in 220 3 phase out. Pure magic.

 

[dalmatiangirl61]

Why the need for 220? It is a 3/4 horse motor, plenty of 110 vfds in the sub horse range. 110 single phase in 220 3 phase out. Pure magic.

From what I've seen, the 220v 1ph to 220v 3ph vfd's are more common. What will the amp draw be going from 110v to 220v 3ph? And who stops with just 1 machine? Bite the bullet and run 220v 1ph into the shop area, now his choice is static converter, rotary converter, vfd, and phase perfect. And lets not forget about bypassing all the machine controls, I like my knobs and switches

 

[memphisjed]

And lets not forget about bypassing all the machine controls, I like my knobs and switches

You are allowed to keep all** the switches and knobs. The kB I referenced even has nice dial and toggle switches, No led screen gibberish or input control wiring to get backwards at least twice.
Maybe not all**, drum switch goes away unless you want to get into wiring for retro look.

 

[jim rozen]

My vote is for a 120 volt input vfd in this case.

 

[jbacc]

Why the need for 220? It is a 3/4 horse motor, plenty of 110 vfds in the sub horse range. 110 single phase in 220 3 phase out. Pure magic.

I agree, I have a 3/4 horse 3 phase motor on my Clausing 15" Drill Press running off 120 single phase power and a VFD. Works great.

 

[Nmbmxer]

Single phase motors on mills and lathes suck, don’t do that. You’ll lose the ability to plug reverse and won’t be able to power tap. If you flip it to reverse without it completely stopping it can jump a phase and keep going in forward.

Using a 120v to 240v vfd is much better. Often making a small pendant near the knee for the low voltage switches is handy. If you have a quill handle instead of the wheel a momentary button for reverse is super handy for tapping holes.

 

[rons]

Easy to buy a VFD with a voltage doubling circuit inside (120 to 240v). A 1Hp VFD would be cheap.