# Solved ---- Help Reversing Motor



## Muskt (Jan 29, 2016)

Hello folks.  Several years ago, I fabbed a grinder to use for my TIG Tungstens & Carbide cutting tools (Last Photo).  (It uses diamond lapidary plates--works exceptionally well.)  I finally decided that it would be much more efficient if the motor could be reversed.  Attached are two photos pertaining to the proposed task of reversing the motor.

FIRST and VERY IMPORTANT--The motor will run in either direction by reversing the yellow and blue leads as shown on the data diagram (First Photo).  I did it.  I just do not understand how to do it via a switch--if it even can be done.

NOW, I am comfortable working with electricity.  However, I am not comfortable about allowing the magic blue smoke to leak out of the motor--Hence my asking for help.

Can any of you advise me if it is possible using the DPDT switch (Second Photo)--or do I need some other type of switch.
If it is possible, could you post a sketch that I (remember that I'm electrically challenged) can replicate with wires out in the shop.

Thanks a bunch
Jerry in Delaware


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## T Bredehoft (Jan 29, 2016)

You have a double pole, double throw switch.

Unplug the grinder motor.  You may have to introduce permanent jumper wires to be able to reach from the motor to the switch.

Start by hooking the yellow wire and the blue wire to the center terminals, one on each side. (nos 2 and 5) Having established that, affix a wire to the lower left terminal, and also connect it to the upper right terminal ( 6 and 1) with a tail long enough to reach the No. two terminal on the motor.. Ditto the lower right, upper left terminal (3 and 4)  to reach the No. 4 terminal on the motor.

Put the switch in the center (off) position.  plug in the plug, watch for magic smoke. If none appears, quickly throw the switch to one side and aback to center (off). Note which way the wheel is going and write it down.  The other way on the switch the wheel will go the other way.

Good luck, it's really pretty easy.


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## derf (Jan 29, 2016)

If the motor is a capacitor start, you may have to use 2 switches, One for off/on and the other for reversing. Wiring through the fw/off/rev will still energize the capacitor when in the off position.


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## Muskt (Jan 29, 2016)

Thanks to both of you.  

First, my DSU  (Designated Spousal Unit) just informed me that we are going out to dinner--No Shop Work This Evening.....
I will try the wiring tomorrow.

Second, the motor has no external caps on it.  It is an old "furnace duty" motor, what ever that is.

Thanks, again.
Jerry


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## David S (Jan 29, 2016)

Jerry.  To add to what has been stated, I would put in a separate switch as an on - off switch.  I am sure you could use a centre off dpdt switch as a center off. but if you inadvertently moved it past off while running things may not be nice.

This way you can use the single ON - OFF switch to do just that.  And when OFF then change the direction switch.

David


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## T Bredehoft (Jan 29, 2016)

David is right, you need a separate ON OFF switch upstream from the DPDT.


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## davidpbest (Jan 29, 2016)

You can do this with a single switch that is 3-position DPDT non-momentary like this one:

*http://tinyurl.com/gpvgysx*
*
David*


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## T Bredehoft (Jan 29, 2016)

QUOTE="davidpbest, post: 365775, member: 40077"]http://tinyurl.com/gpvgysx[/QUOTE]

Those spade terminals would be a snap to wire, rather than trying to snake wires from one end to the other, just crimp them on the female spade terminals.


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## Muskt (Jan 30, 2016)

HMMmmmm...........
Confusion is rampant, now.

I understand how to wire the switch as Tom said in his first post--No problem there.

If I do not install a second switch (in the supply line), some portion of the motor will be energized any time it is plugged in, I think???

Davidpbest says that I can do it all with one switch (which is what I currently have, except that mine has screw terminals)--at least that is what I think he said.  OR, does he mean to use an additional DPDT switch as an on-off switch?

I am not trying to be obstinate, I just don't want to burn up the motor or the shop.

Thanks, 
Jerry


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## CluelessNewB (Jan 30, 2016)

Yes as others have said you will need a second On/Off switch along with the DPDT switch you have for reversing.  Here is a diagram.   Note that  line power is coming in from the left side of the diagram.  Your On/Off switch should switch the black (hot) wire.   I have not shown a ground wire but the motor and any 
metal boxes you use for the switches should be grounded.


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## davidpbest (Jan 30, 2016)

A DPDT 3-position switch has a center position that is OFF.   A normal 2-position DPDT switch does not have a center off position, and thus is sending power from the center terminals to the terminals on the end corresponding to the toggle position.  3-position switches come in two varieties - momentary (which means it is spring loaded to return to the center off position when released - this is NOT what you want), and latching or non-momentary (which means it will lock in any of three positions: right, center-off, left).   All switches can be had with screw terminals or quick slip clip-on connection lugs.   Is this clear now?


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## Muskt (Jan 30, 2016)

SUCCESS!!!!!
No magic blue smoke--Worked first time.
I did wire in a line On-Off switch as several recommended.

Davidpbest===Thank you for your concerns & help.  I now do understand the switch.  The DPDT switch that I had (and used) was not the spring loaded variety, and it is the 3 position type. 

After getting it running, I (very quickly) placed the DPDT (reversing) switch in the center (Off) position.  I wanted to see what would happen.  The motor slowed as though it were going to stop until it reached the RPM where the centrifugal switch wanted to cut back in and just clicked on/off a couple of times.  I guessed that that was not good for the motor, so I pulled the plug.  I will need to remember to leave the reversing switch in one of the "run" positions, and not in the "Off" position.

Anyway, I am quite happy with the operation of my Grinder, and will need about an hour to reassemble the whole unit to get it usable again.

Thanks to each of you who generously offered your help & knowledge.  This is a great group, & I am very glad to be a part of it.

Thanks again
Jerry in Delaware


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## T Bredehoft (Jan 30, 2016)

As happy as you are with your setup, we're happy to have been able to easily help you solve your problem.  If not retired teachers, we've had aspirations in that direction. You're Welcome.


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## davidpbest (Jan 30, 2016)

Ditto what T Bredehoft said.


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