# Another Wiring Job



## tonlin (Feb 10, 2015)

Can anyone guide me in attempting to wire a forward-reverse-neutral switch to an electric motor for a 1938 South Bend "heavy" 9 lathe?

I have included pictures of the motor and switch, however, please note that neither the switch or motor have wiring diagrams (it appears they were removed by a previous owner).


As you can hopefully see in the pictures, the switch is partially broken (if anyone has an extra they can part with, I surely need it). )


The motor is a reversing 1.5 hp General Electric, single phase, 115/230 volt, 1,725 rpm older unit.


I know nothing about the switch except that it is designed to go "forward, reverse and neutral", I think.   

I am ignorant when it comes to electricity so please be elementary with any step by step instruction. :talktogod:







Thanks, guys.


----------



## RJSakowski (Feb 10, 2015)

The switch is a drum switch or motor reversing switch.  McMaster Carr sells them for about $35 (cat. no. 7065K21).   Single phase a.c. motors have a set of start windings and a set of run windings. The run windings are split into two halves, one on each side of the motor.  For 110 operation, the windings are wired in parallel, for 200, they are in series.  Reversing a single phase a.c. motor is done by reversing the leads of one set of windings.  The drum switch does that.  The pictures below are of the drum switch on my old Craftsman lathe showing the left and right sides.  You may be able to repair your switch.  I a brazed a broken contact some forty years ago and it is still going strong. The repair is circled in red.


----------



## jim18655 (Feb 10, 2015)

A picture of the motor data plate and wiring diagram for the switch and motor would be helpful.


----------



## tonlin (Feb 11, 2015)

jim18655 said:


> A picture of the motor data plate and wiring diagram for the switch and motor would be helpful.



Thanks, Jim, I have attached a picture of the motor plate but as I mentioned in my OP, the switch wiring diagram is missing, so I am flying blind on it.

Appreciate the help, thanks!


----------



## tonlin (Feb 11, 2015)

RJSakowski said:


> The switch is a drum switch or motor reversing switch.  McMaster Carr sells them for about $35 (cat. no. 7065K21).   Single phase a.c. motors have a set of start windings and a set of run windings. The run windings are split into two halves, one on each side of the motor.  For 110 operation, the windings are wired in parallel, for 200, they are in series.  Reversing a single phase a.c. motor is done by reversing the leads of one set of windings.  The drum switch does that.  The pictures below are of the drum switch on my old Craftsman lathe showing the left and right sides.  You may be able to repair your switch.  I a brazed a broken contact some forty years ago and it is still going strong. The repair is circled in red.
> 
> View attachment 94653
> View attachment 94654



Thanks, RJ, appreciate your pictures!


----------



## jim18655 (Feb 11, 2015)

Isn't there a wiring diagram on the motor?


----------



## tonlin (Feb 12, 2015)

jim18655 said:


> Isn't there a wiring diagram on the motor?



No, Jim, its long gone, unfortunately. That's why I'm doing this the hard way! :noidea:

TJ


----------



## RJSakowski (Feb 12, 2015)

TJ,

Have you gotten any further help with the motor wiring?  If not, I can give a go with you.

Bob


----------



## tonlin (Feb 13, 2015)

RJSakowski said:


> TJ,
> 
> Have you gotten any further help with the motor wiring?  If not, I can give a go with you.
> 
> Bob



Thanks kindly, Bob, because I have gotten no further. Definitely could use your help. 

Right now, I have the motor and switch with no wiring whatsoever. 

I know I have to choose a supply cord of some sort, preferably something that is rated for 115V since my goal is to stay away from 240V for this lathe, if possible. It was wired for 115V originally, I think. 

So, if you can guide me on the size of the supply cord, I can pick that up and all I will then need for the project will be (as of yet unknown) individual wire(s) between the switch and motor. Am I correct?  

TJ


----------



## RJSakowski (Feb 13, 2015)

tonlin said:


> Thanks kindly, Bob, because I have gotten no further. Definitely could use your help.
> 
> Right now, I have the motor and switch with no wiring whatsoever.
> 
> ...



Hi TJ  
Last things first.  A 1-1/2 hp motor requires about a kw (750 w/hp) which would mean a draw of about 10 amps @ 110 volts.  Depending of the length of cord, AWG 14 should work.  For connections between the motor and the switch, it depends on how your lathe was wired.  My wiring ran through conduit so solid wire worked fine for it.  It is easier to work with than stranded, also easier to come by. For sanity's sake it would be best to have different insulation colors.  Green should be reserved for ground and white for the neutral wire.  Red and black are usually used for the hot wires.  You may be able to buy or beg the needed wires from a local electrician.  If you can't come up with the different colors, at least stick with the ground, neutral, hot wiring convention and attach labels to each end of the wire for ease of identification.  A paper or tape label protected with a clear heat shrink makes for permanent markers.

  A few questions.  Does the motor run now?  Do you have a multimeter or continuity tester.

  Single phase ac motors come in two flavors; capacitor start and capacitor run.  They both have two sets of windings, a start winding set and a run winding set.  Each set is split into two halves one on either side of the armature.  On a capacitor start motor, the start winding is switched off once the motor reaches a certain speed.  This is usually done with a centrifugal switch mounted at the back end of the motor.  You can identify this motor by the switch plate or, if it runs, by a clicking sound when the motor revs up and when it winds down.  The motor doesn't know which way to turn without the start winding.  The start winding provides an out of phase current which biases the magnetic field to start in the desired direction.  To reverse the direction, the wires of the start winding are interchanged which reverses the phase and the magnetic field bias..  This is what the drum switch does.
  A capacitor run motor operates in the same manner with the difference being the start winding is not switched out.  This is usually done to develop more torque.

  The start windings are usually wired in series and in series with the start capacitor.  For a 110/220 motor, the run windings can be wired in series or in parallel.  Capacitor run motors may have a series capacitor as well.

  The first step in wiring the motor is to identify the type. Most motors have an plate on the back of the motor that provides access to a terminal board.  If you remove the plate, you should be able to see if there is a centrifugal switch.  If you don't have an access plate, you may have to pull the end cap off the motor to access the internal connections. 

  Your motor also has two capacitors in the housings mounted on top of the motor.  Because of this, I would guess that you have a capacitor run motor. If you remove the covers, you will have access to the wiring.  Usually, the capacitors are connected with a screw terminal or a  spade connector.  I counted six wires coming out of your motor.  You would have to have some internal connections to give you the 110/220 and reversing options.  I suspect that the capacitors are connected internally so you would have to access those connections in order to identify winding pairs.

  [FONT=&amp]This is a lot to digest but it will give you a start anyway.  As you progress, we can go into more detail.  

Bob
[/FONT]


----------



## tonlin (Feb 16, 2015)

RJSakowski said:


> Hi TJ
> Last things first.  A 1-1/2 hp motor requires about a kw (750 w/hp) which would mean a draw of about 10 amps @ 110 volts.  Depending of the length of cord, AWG 14 should work.  For connections between the motor and the switch, it depends on how your lathe was wired.  My wiring ran through conduit so solid wire worked fine for it.  It is easier to work with than stranded, also easier to come by. For sanity's sake it would be best to have different insulation colors.  Green should be reserved for ground and white for the neutral wire.  Red and black are usually used for the hot wires.  You may be able to buy or beg the needed wires from a local electrician.  If you can't come up with the different colors, at least stick with the ground, neutral, hot wiring convention and attach labels to each end of the wire for ease of identification.  A paper or tape label protected with a clear heat shrink makes for permanent markers.
> 
> A few questions.  Does the motor run now?  Do you have a multimeter or continuity tester.
> ...



Thanks much, Bob. Let me digest some of this, look at my motor's wiring and other items you mentioned, and then get back to you with more questions. Sure appreciate your help!
TJ


----------



## tonlin (Feb 24, 2015)

tonlin said:


> Thanks much, Bob. Let me digest some of this, look at my motor's wiring and other items you mentioned, and then get back to you with more questions. Sure appreciate your help!
> TJ



Ok, Bob, here is what I have found since you gave me some guidance:

1. I have attached pictures of the capacitors, windings and inside of the back end of the motor. I cannot determine if I have a centrifugal switch or not by looking and don't want to run power to the motor until I am sure I know how to connect properly.
2. Note the motor has seven wires coming out of it instead of six.
3. What gauge wiring should I use between the motor and the switch? (I will run all wiring through conduit).
4. Should I use 10 or 12 gauge wire for the power supply cord since I want it about 10 feet long?
5. I have both a continuity tester and multimeter but hardly know how to use either.

Are the pictures and info enough to determine what I have?

Thanks,
TJ


----------



## tonlin (Feb 24, 2015)

Bob, Here are more pictures.


----------



## tonlin (Feb 24, 2015)

tonlin said:


> Bob, Here are more pictures.
> 
> 
> 
> ...



And some more pictures.


----------



## RJSakowski (Feb 24, 2015)

The easy one first.  The National Electrical Code lists 20 amps for 12AWG and 25 amps for 10AWG when sheathed in rubber insulation.  Also 10 AWG has a resistance of about 1 ohm/1000 ft.  At 20 amps and for a 20' cord, there would be a voltage drop of about .4 volts which is a drop in the bucket at 120volts.  12 AWG wire has a resistance of about 1.5 ohms/1000 ft so the voltage drop would increase to .6 volts, again not significant.  From a safety and power loss standpoint, there would not be a problem with 12 AWG wiring both for the line cord and your internal wiring.  10AWG cords are rather cumbersome and it is more difficult to route and make connections.

You have a capacitor start motor.  The spring bronze arms on either side of the bearing open the switch when the motor revs up.  The wiring connected to the switch contacts is in the start circuit.  It is hard to determine anything from the photos of the wiring although it looks like the red wires run to the capacitor.  Trace those wires.  One should go to a winding and the other to the switch.  You need to find the other end of the winding.  A multimeter on the resistance scale  will show a low value resistance between the winding side of the capacitor and the wire connected to the other end of the winding.

The diagram shows a 120/240 volt capacitor start motor wired for 240 volt operation.  For 120 volt, point 1 would be connected to 3 and point 2 would be connected to 4.  Point 5 in the forward run position  and point 8 in the reverse run position would be connected to point 3. All of those points should be available outside the motor housing.

I would label the wires and note how they are connected now.  Then separate them all and try to identify the windings. 

There is an alternative way to reverse a motor and that is to connect the switch contact connected to point 4 to point 3 and the start winding point opposite the capacitor (point 5 in the first diagram) to point 4.  This also reverses the phase of the current in the start winding, running the motor in reverse.

Clear as mud?

Bob


----------



## tonlin (Feb 24, 2015)

RJSakowski said:


> The easy one first.  The National Electrical Code lists 20 amps for 12AWG and 25 amps for 10AWG when sheathed in rubber insulation.  Also 10 AWG has a resistance of about 1 ohm/1000 ft.  At 20 amps and for a 20' cord, there would be a voltage drop of about .4 volts which is a drop in the bucket at 120volts.  12 AWG wire has a resistance of about 1.5 ohms/1000 ft so the voltage drop would increase to .6 volts, again not significant.  From a safety and power loss standpoint, there would not be a problem with 12 AWG wiring both for the line cord and your internal wiring.  10AWG cords are rather cumbersome and it is more difficult to route and make connections.
> 
> You have a capacitor start motor.  The spring bronze arms on either side of the bearing open the switch when the motor revs up.  The wiring connected to the switch contacts is in the start circuit.  It is hard to determine anything from the photos of the wiring although it looks like the red wires run to the capacitor.  Trace those wires.  One should go to a winding and the other to the switch.  You need to find the other end of the winding.  A multimeter on the resistance scale  will show a low value resistance between the winding side of the capacitor and the wire connected to the other end of the winding.
> 
> ...


----------



## tonlin (Mar 2, 2015)

Bob,

Here is some more information if it helps you guess what I have going on with my situation.

My seven wires coming out of the motor are marked as such:

Pink- P1
Black- T5
Brown- P2
Yellow- T2
Orange- T3
Yellow/Black stripe- T4
Red- no markings

Thank you,
TJ


----------



## RJSakowski (Mar 3, 2015)

tonlin said:


> Bob,
> 
> Here is some more information if it helps you guess what I have going on with my situation.
> 
> ...


TJ,
From what I have seen for other GE motors, the main windings are most likely T1 (red?)-T2 and T3-T4 and the P1-P2 wires probably go to a thermal protector.  You need to identify pairs of wires.  This is done with the ohmmeter setting on your multimeter.  First, note which wires are connected.  Then separate all the wires.   The intent is to find out which wires correspond to the points in the schematic sent on 2/24.

I have attached a test matrix.  Print it out and write in the resistance that you measure between each pair of wires.  The boxes with X's can be ignored.  When you finish, you should be able to identify the windings in the motor.  There should be two pairs with the same resistance value.  The thermal protector, if that is what it is, should have a near zero value between its leads.  A wire with infinite resistance to all other wires is probably connected to a capacitor and the start winding.

You should also measure resistance from  the capacitor leads to each of the wires. and to the centrifugal switch.  

It is a tedious job but in lieu of a wiring diagram, about the only way you can safely wire up the motor.    If you don't feel up to the task, another way is to take the motor into an electric motor shop and have them work it out.  It may cost you a few bucks but it will save your sanity.  Once you figure out how to make the motor turn forward and reverse it should be fairly easy to wire up the drum switch and get you making chips instead of connecting wires.

Bob


----------



## tonlin (Mar 3, 2015)

RJSakowski said:


> TJ,
> From what I have seen for other GE motors, the main windings are most likely T1 (red?)-T2 and T3-T4 and the P1-P2 wires probably go to a thermal protector.  You need to identify pairs of wires.  This is done with the ohmmeter setting on your multimeter.  First, note which wires are connected.  Then separate all the wires.   The intent is to find out which wires correspond to the points in the schematic sent on 2/24.
> 
> I have attached a test matrix.  Print it out and write in the resistance that you measure between each pair of wires.  The boxes with X's can be ignored.  When you finish, you should be able to identify the windings in the motor.  There should be two pairs with the same resistance value.  The thermal protector, if that is what it is, should have a near zero value between its leads.  A wire with infinite resistance to all other wires is probably connected to a capacitor and the start winding.
> ...



Thanks much, Bob. I will get to work on this and if I can't handle it, I will default to a local motor shop for help. 
TJ


----------



## tonlin (Mar 24, 2015)

tonlin said:


> Thanks much, Bob. I will get to work on this and if I can't handle it, I will default to a local motor shop for help.
> TJ


Hey Bob and others,

After much time spent (wasted?) as well as frustration, I finally faced the fact that my electrical knowledge is too limited and went to a local motor repair shop. Of course, I won't be able to sit down for a month now, but at least this little project is finished so I can move on after I heal up.  Thanks for all your effort to help me through this, sure appreciate it!
TJ


----------



## RJSakowski (Mar 24, 2015)

I'm glad you got it sorted out.  Do yourself a favor and make a wiring diagram now that you have it wired correctly.    did you get your drum switch sorted out too?

Bob


----------



## tonlin (Mar 25, 2015)

RJSakowski said:


> I'm glad you got it sorted out.  Do yourself a favor and make a wiring diagram now that you have it wired correctly.    did you get your drum switch sorted out too?
> 
> Bob


Hi Bob,

I had to buy a new drum switch, apparently my old one either couldn't be repaired or the shop just didn't want to do it. They never really answered me directly on that question. In fact, they really didn't want to do the job (too small) but felt sorry for me in the end and worked it in.

TJ

TJ


----------



## RJSakowski (Mar 25, 2015)

tonlin said:


> Hi Bob,
> 
> I had to buy a new drum switch, apparently my old one either couldn't be repaired or the shop just didn't want to do it. They never really answered me directly on that question. In fact, they really didn't want to do the job (too small) but felt sorry for me in the end and worked it in.
> 
> ...


Well now you can settle into cutting metal instead of stripping wires!


----------



## tonlin (Mar 25, 2015)

RJSakowski said:


> Well now you can settle into cutting metal instead of stripping wires!


Hey, that's the ultimate goal anyway! Look out now, I'm ready to do some damage!
TJ


----------

