Need Assistance: Forward/Reverse Wiring a Lathe Motor

[steveh_131]

Looking for a little help from some of you wiring experts.

I'm trying to wire up a fairly old lathe. I put a new (used) AC motor on it, that the specs claim is reversible. I also picked up a cylinder switch to handle forward and reverse switching.

I ran a 4-wire armored cable from the switch to the motor. Looking back, I'm not sure there are enough wires, but you tell me.

Here are some pictures of what I'm working with. I was hoping someone could give me an idea of how I should go about wiring this thing. Thanks in advance for any help!

Plate on the motor:

Motor's wiring diagram:

Motor terminals:

Switch terminals (there are 3 terminals on each side):

 

[Mr Evilwrench]

Shouldn't be hard if all it takes is switching the red and black between L1 and L2, all you need is a DPDT (double pole double throw) switch, and two wires. It looks like the switch you have rotates, right? If so, connect red to the top (or bottom) and black to the bottom (or top) terminals and the motor to the middle ones. I do have a question, though, why would you want to reverse a lathe?

 

[steveh_131]

Shouldn't be hard if all it takes is switching the red and black between L1 and L2, all you need is a DPDT (double pole double throw) switch, and two wires. It looks like the switch you have rotates, right? If so, connect red to the top (or bottom) and black to the bottom (or top) terminals and the motor to the middle ones.

That was my thought at first, but I don't believe it is that simple.

This is a split phase AC motor, and the wiring diagram for the switch looks like this:

There are multiple windings at work, I believe.

I do have a question, though, why would you want to reverse a lathe?

That is a question for the machinists here. I'm really not sure. I'm helping my dad wire it, but I am certainly no machinist!

ETA: Off the top of my head, taps and dies would be one good reason to make it reversible.

 

[Mr Evilwrench]

Well, often you'll have the rotor windings and stator windings, and a run capacitor to shift the phase 90° to make it run one way or the other. You can switch one of those with an SPDT (single pole double throw) switch, very very easy. So you're saying you have the one in the upper right there? Is there a capacitor?

I always run my taps and dies by hand; they need to go real slow.

 

[steveh_131]

Well, often you'll have the rotor windings and stator windings, and a run capacitor to shift the phase 90° to make it run one way or the other. You can switch one of those with an SPDT (single pole double throw) switch, very very easy. So you're saying you have the one in the upper right there? Is there a capacitor?

Yes, upper right, and no capacitor.

As a split phase motor, there is a start winding and a run winding. The start winding is energized for 2-3 seconds before it's shut off by a centrifugal switch of some sort. The run winding stays energized.

I'm reading that the start winding is the place to reverse the polarity - So based on these wiring diagrams I'm thinking that switch terminals 1 and 5 should go to L1 and L2 on the motor.

Then the red and black wires should be removed from their terminals at motor terminals 2 and 4 and be connected to 3 and 4 on the switch.

Then switch terminals 2 and 6 should be connected to the wall plug - but this leaves the far left motor terminal connected to nothing... Is that just a ground?

 

[bluewraith]

Shouldn't be hard if all it takes is switching the red and black between L1 and L2, all you need is a DPDT (double pole double throw) switch, and two wires. It looks like the switch you have rotates, right? If so, connect red to the top (or bottom) and black to the bottom (or top) terminals and the motor to the middle ones. I do have a question, though, why would you want to reverse a lathe?

On our atlas using reverse is the only way to cut metric threads. Swap the gears around, etc. Since it wasn't really designed to cut metric, you have to reverse out of the cut or you'll never get back to zero.

 

[Mr Evilwrench]

Well, you have a connection diagram there in the upper middle, and it and the motor diagram call out all the numbers. Do it that way, you probably won't have an explosion, at least. Looks like you'll need the 4 wires to the motor and 2 to the power.

 

[Dj15802]

As stated above... To reverse you switch the two hot wires. ( red and black)

 

[Shadow]

Looks like the drum switch you have is for 240 3phase .

 

[Shadow]

Shouldn't be hard if all it takes is switching the red and black between L1 and L2, all you need is a DPDT (double pole double throw) switch, and two wires. It looks like the switch you have rotates, right? If so, connect red to the top (or bottom) and black to the bottom (or top) terminals and the motor to the middle ones. I do have a question, though, why would you want to reverse a lathe?

This !!!

 

[steveh_131]

Looks like the drum switch you have is for 240 3phase .

It will do both, the switch diagram shows how you can use it for a split phase motor as well.

As stated above... To reverse you switch the two hot wires. ( red and black)

I agree with this, but here is my question.

The red and black wires seem to go to the start winding. If I disconnect them from their posts and wire them directly to the switch, will that bypass the centrifugal switch that is supposed to cut off the start winding after a few seconds? Because if that happens, I'll burn up the motor.

So do I run the current directly to the wires, or do I need to run one to that post on the far left of the motor terminals?