lathe motor

37 chief · Mar 24, 2021

I have a question for the electric people smarter than I am. I have a lathe with a one hp 220 three phase drive motor. I purchased a phase converter box with capacitors already wired. All I need to do is connect the power wires. The box is marked 220 power in three ph going to a idler motor, and 3 ph going to my lathe motor. I think I was wired for dummies. Every thing is marked very plane. After all that. Here is my question. The box says it is for 5 hp. My idler motor is 3 hp. Will I have the right amount of three phase to run my 1hp lathe motor event tough the converter box says 5 hp, and the idler motor is 3 hp? I tried to call the company, they must be out of business. That's what happens when something sits on the shelf for a few years. Thanks for any help. Stan

Jeff NWOH · Mar 24, 2021

I would assume (you know what they say about assuming) that it is set up for a 5 hp idler motor. Generally, your idler should be 1.5 times the size of the largest motor you want to be able to start with it. You can run anything smaller than that without a problem. You can also get away with starting larger motors if they have no or relatively small loads on them at startup.

Whether or not your box will be happy with a smaller idler, i can't say for sure. I doubt it would hurt anything to try and I would speculate it will probably work.

RWT · Mar 24, 2021

I built my own idler a few years ago for a 5 HP lathe. Since I built it it is balanced.

I also run my 1 HP mill on it with no problems. It is probably not balance as well but it is not a problem. Previous to this mill I ran a 1/2 HP mill on this set up.

To comment further, my 5 HP lathe starts fine on low speed with the 7 HP idler. Most of the time if I want to run on high I bring on another 5 HP of idler. It's 5 because 3 wouldn't do the job. There is a more capacitance with the 5.

I run the mill on the 7 HP idler. I should rig it so the 5 HP runs without the 7 but I haven't done it yet.

Anyway, you won't have any trouble running the 1 HP.

RT

Geo-TH,In · Mar 25, 2021

Before my dad passed in 1985, he made phasers for farmers.
There were 2 types. One used only capacitors. The others used capacitors and a 3 phase motor(rotor)
Each type you have to be balanced for load, use the right amount farads. Each used a 3 phase contactor. If you plan to use the rotor type(a second motor) you have to get rotor going before the connect it to you 1 hp motor.

I would think it would be easier and cheaper to replace the motor with a 220v single phase.

Its been almost 40 years since I built my last phaser for my dad.
George

lathe motor

37 chief

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Jeff NWOH

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RWT

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Geo-TH,In

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