Maybe this isn’t the place to post this but I know this is where the smart guys are and I need answers. Lathe motor single phase 220 volts. Runs fine in reverse but forward I have to spin it by hand to move than it doesn’t have any torque to cut material. Like I said backward is great. What is the problem? I had a rotary switch and contacts look clean.

Recently went through this and after being sold a new motor by the "tech support" if wound up just being a contactor that the members on here helped me diagnose.
The contactor reverses which leg of the 220 the motor starts with, thereby setting the direction of rotation. Also look on ebay & amazon as the MFR was out of stock but plenty were available and cheaper to boot

BTW: I have a nice 2 HP 220 single phase reversible motor for sale

That’s it? No electrical engineers on here today?

Due to the fact that I'm not clairvoyant, what is the make and model of your lathe. Without knowing the particulars of your situation it's hard to give any useful comments.

What the motor is attached to has zero to do with why an electric motor spins great one way and barely the other. I described what the motor is in my first post question. But thanks for reply

Y'know, when you're asking for help even the dumbest questions deserve an answer !! (And I'm by no means saying 6PakBee's question is dumb !)

It has everything to do with it. It COULD BE a simple split winding single phase motor with a starting switch or it COULD be a capacitor start single phase motor, or it COULD BE a capacitor start, capacitor run, single phase motor. With the lathe make and model, someone who was trying to help you could google the wiring schematic and offer some opinions. But as it is, my crystal ball is in the shop for repair so I can't be of any help to you.

The motor did not come on the South Bend lathe, it was installed by previous owner 40 years ago, 220 volt single phase one capacitor (all I can see) with a rotary switch to change direction. This weekend I’ll get it out to get info on tag but first I’ll swap connections on switch to see if there’s a change to rule out the switch.

That helps immensely.

Reversing an AC Motor

It sounds like you have a bad reversing switch. Now that I've seen what you have, all the symptoms you describe of running acceptably in one direction and not running in the other direction unless manually turned indicates that the starting switch and starting capacitor are operational in one direction and not in the other. That typically is a switch problem. Your comment about the motor not having any torque when you manually spin it to start sounds like you have a capacitor start/capacitor run motor. The motor nameplate details will firm that up.

Thanks I’ll get it out from under the lathe this weekend (a job no doubt) has to come out the front door, got a big cabinet against the end. I’m hoping nothing major to motor, capacitors are easy to replace. Motors real dirty too, dust bunnies.

Got some pics, two capacitors front one sparked big time when touched with screw driver.

One more, switch was fine

Capacitors will do that as they store the electrons, cdo be careful as depending on the size of the capacitor the energy stored can be lethal
That capacitor in the lower part of the pic (red and orange wires) is a strong suspect as it appears to have been leaking. Wait for one of the more astute members to verify.
Wouldn't doubt you could swap the capacitors to confirm but also be aware they are polarity sensitive and can blow up if hooked up backwards

Thanks, I’m waiting to hear more before changing anything. Hope I didn’t mess it up when it arced

From your symptoms I guessed that it was a capacitor start, capacitor run motor. If you look at the attached sketch, the way the motor is reversed is that the two leads for the start winding are switched by the directional switch. Sometimes the run winding is switched but that is rare. What I think is happening is that in the direction that operates normally, the start and run windings are connected. But in the other direction one of the leads for the start winding is not connected which leads to a no start and poor peformance. My money is still on your reversing switch.

BTW, shorting a capacitor doesn't hurt it. In fact, if you are working on something with large capacitors it's normal procedure to discharge them rather than get knocked on your butt.

I’ll get the switch off from under the bed to look at it better but It 110 did go thru each contact when rotated each way. Might be missing something and I need to trace wires back to motor, could be a break along the way. Just house wire

110 volts with a 220 motor? If you take readings to the neutral (ground) you can get misleading results at times. What I would recommend is measuring across the winding that is switched and check for 220 in both directions of the reversing switch. I'm going to guess that you won't have 220 in one of the two directions.

There is no 220 on single phase just two 110s to make 220, now 3 phase is different, 220,110,110

Whoa! There most certainly is 220 single phase in a typical service entrance. Water heaters and electric furnaces all use both of the 'hot' leads for 220 volts. A 220 volt outlet such as a NEMA 6-15 or a 6-20 will have both 220 leads and a ground, no 110 volt. My caution is that if you are measuring one side of a 220 volt winding to ground, you may not be accurately accessing the situation.

In Va, my panel box has two leads coming in, both 110, I wired my entire house and work shop. When a 220 appliance needs to be wired up one leg from both sides of 110 makes the 220 plus the common (ground). Now my shop in town has 3 leads, one 220 the other two are 110 (3 phase) plus a ground. Maybe other parts of the country has another setup ?? I have a single phase 220 RotoPhase motor (50hp) to manufacture the third 3 phase leg (220) to run the other machines. Like I said There’s only two legs of service cable (single phase 200 amp) coming into that box. I can take pics if you like. I might be not interpreting what you mean?