# FWD/REV Switch Wiring



## jbolt (Feb 26, 2017)

I have a 220v gear motor left over from my CNC mill conversion that originally was used as a power Z drive. I want to re-purpose this motor to my heavy duty drill press to move the table up and down.

The motor was originally switched via contractors and momentary switches. I would like to know if the rotary switch that was used for FWD/REV on the mill motor could be used for this gear motor instead of the contactors. I can fit the rotary switch in the existing electrical box on the drill press.

This is the wiring diagram on the grear motor. It has three wires, red, white & black. Looking at the original terminal block the red & white wires had a 6uF capacitor bridged between them.




Here is the original rotary switch from the mill. It has 2 wires in marked 2L1 & 2N1 and 4 wires out marked U1, U2, Z1, Z2.




I rung out the wires so here are the load paths.

FORWARD

2L1 ---> U1 & Z2
2N1 ---> U2 & Z1

REVERSE
2L1 ---> U1 & Z1
2N1 ---> U2 & Z2

My mill did not come with a wiring diagram for the rotary switch. I found one for a Griz mill and it looks like the spindle motor is a 6 wire motor.




So is it possible to use this rotary switch on the 3 wire gear motor? If so how would it be wired? Do I need to keep the 6uF capacitor?


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## CluelessNewB (Feb 26, 2017)

I think you have a rather simple capacitor run motor.  If I am correct you can reverse it by moving just one connection.   Yes you will need the 6uf capacitor. 
Below is a book diagram of they type of motor I think you have:



And here is my assumption of what I think your diagram is.   I assume the thing I have the red arrow pointing to is the 6uf cap.  To change directions you disconnect the power going to "CW" (my red X)  and move it to "CCW" (my blue wire)


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## CluelessNewB (Feb 26, 2017)

Oh I don't read or speak Chinese but Google translate helps!   I believe that is in fact the capacitor.


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## jbolt (Feb 26, 2017)

Good call on using the translator!. The symbols by the wires are colors. The red and black translate. Top is red and bottom is black.

I found a manual that shows the wiring of the gearmotor using the contactors so it looks like you are correct. I just need to figure out the switch.


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## CluelessNewB (Feb 26, 2017)

As for the switch, were your measurements done with all those jumper wires connected?   If yes your switch may work by removing some of them.   If you measured with the jumpers removed I haven't been able to figure out any way it will work.   A simple double pole, double throw center off switch will work.


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## jbolt (Feb 26, 2017)

I measured with the wires jumpered but it was easier just to rewire the switch.

I rewired the switch to this. I believe this is correct though I'm not sure how the capacitor works when bridged between the CW and CCW wires but that is how it was previously wired.


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## jbolt (Feb 26, 2017)

I verified the switching works as wired above with a MM. 

WITHOUT the motor hooked up and the capacitor bridging the red and white wires out of the switch, the voltage on the common wire (black) drops to zero volts and the white or read lead depending on switch position (FWD/REV) goes to 240v? I'm not sure if this is correct or a condition of the motor being disconnected?

I need someone confirm the placement of the capacitor before I hook up the motor.


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## CluelessNewB (Feb 26, 2017)

I think your diagram above is fine.


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## jbolt (Feb 27, 2017)

Thanks for your help Rich. I have installed and working.


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## markba633csi (Feb 27, 2017)

Looks like it would work fine,  you probably could connect line 1 direct to motor common and double up on the other contacts for reliability.  Does the motor have a center off position? Otherwise you would need another switch for on/off. 
Mark S.


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## CluelessNewB (Feb 27, 2017)

markba633csi said:


> you probably could connect line 1 direct to motor common



It's a 220V motor so no you don't want to direct connect.


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