# ok to replace a 3 position drum switch with a 3 button momentary switch?



## richl (Nov 8, 2013)

i just burned up a starter/run capacitor on my south bend mill yesterday, part of the reason is the drum switch is a bit funky, if you turn it fully to the right or left it engages the motor and remains in a starting state, you need to give the switch a gentle turn slighly in the opposit direction to get the continous run safe stsate... else you burn up a starter/run capa,citor.

I see 3 position drum switches on ebay, as well as more modern looking forward reverse stop momentary switches... will the momentary switch work in this application or do i need to look up drum switches for this application?

thanks for the help!

rich


----------



## epanzella (Nov 8, 2013)

richl said:


> i just burned up a starter/run capacitor on my south bend mill yesterday, part of the reason is the drum switch is a bit funky, if you turn it fully to the right or left it engages the motor and remains in a starting state, you need to give the switch a gentle turn slighly in the opposit direction to get the continous run safe stsate... else you burn up a starter/run capa,citor.
> 
> I see 3 position drum switches on ebay, as well as more modern looking forward reverse stop momentary switches... will the momentary switch work in this application or do i need to look up drum switches for this application?
> 
> ...


A momentary switch is, well, momentary. It only passes current while you're holding it. Let go and the party's over.


----------



## Tony Wells (Nov 8, 2013)

Without seeing a schematic, I cannot give a solid answer, but I would be very surprised if the drum switch had anything at all to to with any switching of capacitors. They generally are used only to provide a method of arranging the windings to give you a forward and reverse. It's not impossible that in one position or the other that the coil leads that are routed up to the drum are not making good connections, and you are not getting the proper windings to be energized. 

If you have lost a capacitor, or a winding has burned out, look for other problems and stick with a replacement drum switch. I don't believe there is a way to substitute a pushbutton for a drum switch, unless you mean a complete start/stop station with reverse. You could build that, but you would need some contactors and a control transformer, unless you wanted to use heavier switches and high voltage coils in the contactors. It would be far more of a project than simply replacing the drum.


----------



## Tonym47 (Nov 9, 2013)

Tony Wells said:


> Without seeing a schematic, I cannot give a solid answer, but I would be very surprised if the drum switch had anything at all to to with any switching of capacitors. They generally are used only to provide a method of arranging the windings to give you a forward and reverse. It's not impossible that in one position or the other that the coil leads that are routed up to the drum are not making good connections, and you are not getting the proper windings to be energized.
> 
> If you have lost a capacitor, or a winding has burned out, look for other problems and stick with a replacement drum switch. I don't believe there is a way to substitute a pushbutton for a drum switch, unless you mean a complete start/stop station with reverse. You could build that, but you would need some contactors and a control transformer, unless you wanted to use heavier switches and high voltage coils in the contactors. It would be far more of a project than simply replacing the drum.


Check out E&E Controls Brewster N.Y. on line catalog it has schematic for what you are looking for


----------



## furpo (Nov 9, 2013)

Push Buttons would be fine as long as you put a forward/reversing motor starter in also!
It is done all the time in industrial equipment


----------



## HomeMetalMan (Nov 9, 2013)

Unless Rich you are conversant with obtaining the individual components and then interconnecting them, then purchasing a ready made starter is the way to go, albeit expensive. They do have the advantage of having the facility of adding remote push buttons in addition to those on the starter itself. Particularly useful for adding an emergency stop. Also, they will not restart automatically when the supply returns after a power failure.

As Tony says it is unlikely that the failed capacitor is due to your drum switch and will not be switched by a starter as above, other than the power being switched on and off the motor as a whole.

For a typical US supplier see here http://ab.rockwellautomation.com/Motor-Control/IEC-Reversing-Starters#/tab2  There is of course a large number of other suppliers.

Harold Hall


----------



## rdhem2 (Nov 9, 2013)

I also do not think you drum switch had anything to do with the start capacitor failing.  The switch you refer to is in the motor, called a centrifugal switch actuated by the spin of the rotor.

A 3 position momentary switch will not come close to doing what you want.  As already mentioned they are well, momentary.  You desire a maintained device.  Also pushbuttons are rated pilot duty, meaning they will not handle the continuous current flow desired by your motor.  In place of a drum switch, which does not provide any overload protection for your motor, you would use a manual or magnetic motor starter.  These starters do provide motor over current protection.  Remember, the breaker or fuses protect the wire.  The starter protects the motor.

In place of a motor starter they make motors with factory installed THERMAL OVERLOAD PROTECTION.  These leads in the motor are marked as P1 and P2.  They can be connected directly into the motor circuit or used as a signal in a control circuit.  Either way, you get motor shut down when it draws excessive current.


----------



## richl (Nov 10, 2013)

Thanks for all of the replays... good information here to think about. I ordered the capacitors , I will probably look into replacing the drum switch with another drum switch. I will be keeping an eye on this.... hopefully I will not be replacing more expensive parts.

Thanks for all the great information!

Rich


----------



## bkcorwin (Nov 10, 2013)

You could probably rewire the system so n place of the motor you used a couple of contactor's. Then you could not we momentary switches


----------

