# Wiring a bandsaw switch...



## frankp (Oct 29, 2007)

So I got my bandsaw running and decided to replace the switch with a push button 800S from Rockwell Automation. I have a small problem, though. This particular switch is a "locking on" Start button with a momentary Stop so if I press Start, the machine runs and the button returns to its original position. If I press Stop, the connection breaks and the button returns to its original position. The premise is that if power is lost while the saw is running, the blade will not start up again when power is restored.

My problem is, the saw powers on immediately upon plugging the power chord into the wall outlet, and only stops while I'm holding the Stop button. If I release the Stop button, the motor begins again instead of staying off. This is basically the opposite of what I would expect, however, this is the only wiring I have found so far that doesn't cause a short across the switch somehow. It's like the push buttons are backwards, but they are keyed buttons (I checked) so that's not possible. If anyone is willing to spend a few minutes to try and help me figure this out, I'd really appreciate it. Rockwell has been less than helpful because I'm unwilling to pay for a support contract. I won't be buying from them again in the future.

The 220V power is 2 hot wires with a ground (neutral) wire.

I currently have it wired as input (from the power outlet) line 1 to position 1 of the switch with output (to the motor) line 1 on position 2 of the switch. At position 3 of the switch, I have both input and output line 2. Ground (neutral) bypasses the push button switch altogether.

Here's the circuit Rockwell's documentation says works. The "N.O Aux is a 'normally open' contact the closes when the coil (M) is energized." (That's how the safety mechanism is supposed to engage.)


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## rrich (Jun 24, 2009)

Is there more to the circuit diagram?

What is the O.L. thing?


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## woodnthings (Jan 24, 2009)

*The O.L. thing is probably*

The thermal Over Load device. :yes: bill


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## Zircon (Aug 1, 2009)

*start switch does nothing*

As I look at the diagram, it is wired to do exactly what it is doing. Current flows from point 1 to 2, then down to the coil M closing the contacts up to the motor and back out L2. The on switch is not in the circuit. The circuit is wired to be on all the time and you can stop it only momentarily by pressing the stop button. You need to connect the wires to different terminals on the switch to get the on button into the circuit. Other diagrams, picture of the switch?


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## TomC (Oct 27, 2008)

_"The circuit is wired to be on all the time and you can stop it only momentarily by pressing the stop button. You need to connect the wires to different terminals on the switch to get the on button into the circuit. Other diagrams, picture of the switch?"_

_The above statement is not correct. When you power up the circuit nothing should happen because the start button contact is open. When you push the start button the M coil is energized and closes the aux contacts so the M coil stays energized when the start button is released. When you push the stop button you deenergized the M coil and the aux contacts open so when you release the stop button it does not restart because the circuit is open._
_Is there any addition contacts on the M coil that are used to put power to the motor?_
_Tom_


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## woodnthings (Jan 24, 2009)

*If it's wired correctly then?*

Is the switch defective? Your explanation makes sense, so what gives here? :blink: bill


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## TomC (Oct 27, 2008)

I'm not sure if he has it wired correctly or not. I can not understand from his explanation. However, you will notice that the only circuit he shows is for the M coil. It puts 220V across the M coil. The drawing shows the two power line but not where they go (other than to energize the M coil). Normally the M coil closes contacts that put power to the motor and any aux contacts. Therefore any time you deenergize the M coil the contacts open to the motor and the aux contacts open so it will not restart on it own. Also, this circuit should not allow the motor to restart upon losing power.
Tom


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## TomC (Oct 27, 2008)

Frank,
I believe I have figured out how you have the switch wired. Tell me if I am correct. You have line one going throught the stop switch and then at contact 2 going to one side of the motor tand the other motor lead is connect to the other side (can't remember contact #) of the M coil (right hand side of diagram). This would make the circuit work the way you describe. When you power up the stop contacts are closed so you have power at contact #2 and power on line 2 and the motor runs. When you push the stop button you take power away from contact #2 and the motor stops until you release the stop button. If this is the way you have it wired I do not believe the stop contact is designed to handle motor amps. This circuit should only handle the amps needed to energized the M coil. Very minor amperage. Look at the M coil and see if you see any additional contacts such as L1/L2 and M1/M2. These contacts shouls handle the motor amps. That is where you put L1/L2 to the motor. I'm not sure if it will have one set or two, but I think you should get the idea of how this should work.
Tom


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## frankp (Oct 29, 2007)

Zircon, the problem with your assertion is that the current shouldn't flow from point 2 to M until I press the start button. M is supposed to be "open" until I press the start button, but it doesn't seem to be working that way.

TomC, yes you have my current wiring correctly understood. The problem is, the only "coil" I see in the switch is a metal contact between node 1 and node 2 in the device. Node one and node 2 are both connected to the same "hot" line. Between Node 2 and Node 3 is _supposed_ to be "*normally open*", which implies it shouldn't work until I press the start button. The only thing I can think is the saw is actually running at 110 instead of 220, or the switch doesn't work as advertised.

I've been trying to find out from Rockwell whether or not I have a defective switch or there is something missing but, as I said, they won't actually give me any support unless I pay for it, which really pisses me off. 

Either way, I'll try and wire it up again tonight and go through all the options as I did originally. I lost the paper I was writing all the different possibilities on so I'll have to start over. Last time I only came up with two configurations that didn't short the circuit and blow my fuse, one that worked and one that didn't. I don't think I got through all the possible wiring options though.

Thanks for the help, everyone.


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## TomC (Oct 27, 2008)

Frank,
If you have lead 1 connected to terminal 2 and lead 2 connected to terminal 3 *DO Not* push the start button. This will be a *DEAD SHORT* betweem lead 1 and 2. The M coil is a relay that should have contacts for L1 if single pole relay and for both L1 and L2 if it is a double pole relay. 
Tom


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## Boweevil (Aug 27, 2009)

Have you verified if the aux contacts that you are connected to are actually Normally Open? There are often both N.O. and N.C. aux contacts on a motor starter or relay.

The M coil in the schematic is the coil for the motor STARTER or motor starting relay, NOT the motor itself. The line voltage that actually runs the motor should come through the main contacts of the motor starter or starting relay.

There is a section of the schematic that is missing: the section showing the actual wiring of the line voltage to the motor itself.


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## TomC (Oct 27, 2008)

Boweevil said:


> Have you verified if the aux contacts that you are connected to are actually Normally Open? There are often both N.O. and N.C. aux contacts on a motor starter or relay.
> 
> The M coil in the schematic is the coil for the motor STARTER or motor starting relay, NOT the motor itself. The line voltage that actually runs the motor should come through the main contacts of the motor starter or starting relay.
> 
> There is a section of the schematic that is missing: the section showing the actual wiring of the line voltage to the motor itself.


 Boweevil,
From his discription he may only have the push buttoms and have to supply his own relay with its aux contacts.
Tom


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## woodnthings (Jan 24, 2009)

*I've been following this thread and*

Maybe it's just me, but I would ditch this whole switch and simply get a double pole, double throw switch from Grizzly for about $12.00. This is for a bandsaw after all. The idea behind this Rockwell switch is that the IF the power goes out, the tool will NOT RESTART when it returns. WHO cares? If the power goes out in the middle of a cut, you're looking for the flashlight or the way out the door, and hopefully it's daytime and you have a window for light. IF you have any memory at all, you'll know that the saw is still ON when the power comes back and will have shut the thing off by then. I think the safety switch idea is fine for commercial and industrial shops, where union rules and lawsuits are the order of the day, but for a homeowner shop, it's all too much. I've got both types of switches on my tools, and I don't foresee a situation where all this is necessary. UNLESS there is a momentary drop and the power comes back on immediately, still turn off the machine anyway, safety first rule. JMO, :yes: bill


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## frankp (Oct 29, 2007)

woodnthings, if I don't find the right wiring option, that's exactly my plan. I spent more than I intended on the switch and would have just gotten a paddle switch if I'd realized this one would be so expensive. At this point, though, the money's spent and I'd rather not spend more if it's not necessary.

TomC, I think you may be correct in what you're saying to boweevil. It certainly seems like there is something missing from the switch. This is supposed to be the simplest wiring scheme for this switch but I must admit, as an electrical engineer, I feel embarassed that I can't figure out what's wrong.


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## rrich (Jun 24, 2009)

Guys,
I may not be the sharpest tack in the box, however...

I don't see the labeled contacts for the power that is being supplied to the band saw motor. All that I see is the internal circuit for the magnetic mechanism. 

IMHO, if the thermal overload IN THE SWITCH is tripping when only connected to the 230 V phases, the switch is looking for neutral on L2. (i.e. The band saw motor is not connected to the circuit.)

In the diagram there should be additional Ln terminals for switching the power to the motor. In the diagram, the AC should never flow through the shown part of the switch to the band saw motor.

But as I said I'm not the sharpest tack in the box.


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## Zircon (Aug 1, 2009)

*wiring diagram*

My original post described what was happening, not what was supposed to happen. That said, Tom's info is right on. I made a simple diagram that if you follow it, it will work. You should have only been concerned with connecting the line leads and the motor leads to line1 and line 2 and load 1 and load 2. The other connections should have been made at the factory but since you have gotten into the switch, you will have to check them. I left out the motor overload for simplicity. good luck.

When you press start, you energize the coil and contacts A,A,and a close, the motor starts and continues until you break the circuit with the stop button.


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## frostr2001w (May 21, 2009)

Now I see the problem.. YOUR AN ENGINEER!!!.Just kiddingfolks. In reading thru this post I did not see it mentioned, but are you using a full set of prints and a VOM meter?


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## woodnthings (Jan 24, 2009)

*Could it be as simple as:*

Line 1 goes to No. 1 , Motor goes to No. 3 and is hard wired to line 2?
This does not seem like a douple pole switch diagram as posted above.


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## Zircon (Aug 1, 2009)

*IF*

If circle M in the diagram represents the relay coil and if the OP really has a 220V motor starter and not a 110v, then the diagram can be completed as shown where contacts A and A and M N.O. Aux. close when the start button is pressed and it looks just like my diagram above.

If circle M represents the motor, the diagram makes no sense for a 220v setup where you have to disconnect both L1 and L2. L2 would still be connected to the motor.


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## Zircon (Aug 1, 2009)

*start button*

I know what's wrong now. You have points 2 and 3 connected to the two normally closed contacts on the start button. Switch points 2 and 3 to the two normally open contacts as shown in the diagram and you are good to go.


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## rrich (Jun 24, 2009)

Zircon said:


> I know what's wrong now. You have points 2 and 3 connected to the two normally closed contacts on the start button. Switch points 2 and 3 to the two normally open contacts as shown in the diagram and you are good to go.


What isn't shown is that relay coil that is activated with the NO Aux relay. As long as the NO Aux contacts are closed, power is supplied to the coil that is closing contacts A & B. When power is lost or the power to the relay coil is interupted the main contacts A & B are opened.


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