Old Delta Triple Duty Grinder - wiring diagram wanted

I have a Delta/Rockwell 7" Pedestal Grinder, model 23-105M, single phase, I think this is 40's vintage. It was my grandfather's, was re-wired at some point with a new switch and the lights were taken out of the circuit. Then it was taken apart and stored. I just dusted it off and put it back together but my wiring attempt has gotten enough sparks that I'd really like to find the wiring diagram for it. In my searches I've found the diagram for the 23-294 but that wiring looks nothing like what I've got. It doesn't seem like it should be that hard: I've got two wires from the motor, two from each of the lights and two from the power cord...the switch has been replaced but it looks like it was a basic toggle switch. There are no relays, capacitors, etc., that I can see. Thanks for any help or advice!

Clay

I’ll assume the grinder is 110v? I’m not aware of any 220V devices without three pins, two hot legs and a ground leg. Pretty simple circuit. Plug-switch-motor. Switch can be single or double-pole, all you’re doing is interrupting the circuit either by breaking the current carrying conductor(black wire) or the current return path(white/neutral leg) or both. If the motor doesn’t spin in the right rotation swap the legs and *most* 110v motors will spin the other rotation. Match the same wiring to the lights and you’re done.

If you’re redoing the whole affair, I would recommend upgrading the wire to three conductors and adding a ground leg. Literally can just be a ring terminal somewhere on the main body of the machine. That gives any “loose” electrons an unimpeded path to earth and prevents you getting shocked.

If you’re getting sparks, my first impulse is either A) there’s a short somewhere; decayed insulation, a cut or break in the cord, possibly even some bit of grinding dust giving those electrons a better path than the motor commutator and brushes. Conversely, B)this could be a 220V device and you’ve missed one of the wires and are making your own short. I think A) is far more likely.

Don’t overthink it.




Be safe and stay healthy





Jeremy

Jeremy,

Thanks for the reply - yes, its 110V, and there is a ground on the plug. That all sounds logical which is good! I'll mess with it some more.

I'd be a bit surprised if there wasn't a start capacitor on it somewhere - assuming single phase.
Wiring on these has been beaten to death over at OWWM.org, use advanced search, "triple duty wiring".
I'd post direct links but it looks like there are 57 varieties of these machines.

Many thanks for the search tip, I will take a look over at OWWM And yes, I ran into the same thing, it's the Heinz of grinders!

Pics.

Single phase grinder motors are usually split phase induction since the starting torque requirements are minimal. Dual voltage windings or single? Pics of the motor nameplate would be handy along with the insides of the pickerhead (motor termination box).

Here's the plate:



Don't have one of the terminal box (yet)

Thanks

Key here is whether it rotates absolutely freely when not under power, or if it has some drag to it.

If totally free, it may be a "PSC" motor that uses a capacitor, but no start switch. Many better grinders were made like that, because they are also smoother in operation.

If there IS "drag" then there may be a centrifugal automatic starting switch, and you may be feeling the drag of the centrifugal system on the switch. In that case it might be either "split phase" (resistance start) or capacitor start.

ClayS said:

Here's the plate:

View attachment 310419

Don't have one of the terminal box (yet)

Thanks

Click to expand...

Well I'll be dipped..I have that exact same guy in my shop..complete with lights, guards, tool rests and two cast iron water cups. Got it free, if I recall.

Stuart

Without having any sort of visual on the field wiring, I'm forced to rattle off some guesses blindly.

With two leads coming from the stator core, two from the light fixture, two from the AC power cord and ostensibly a single pole switch, the incoming ungrounded conductor should land on the switch. From the load side of the switch it should get pigtailed to one side of the stator windings and the ungrounded conductor for the light fixture. From there the load side of the stator windings and the light fixture get pigtailed to the "neutral" of the power cord.

Sparking indicates either a short circuit or ground fault. Chances are something is wired incorrectly or you have damaged insulation somewhere in the circuit. Check your connections and look for evidence of arcing. Ohm the windings to ground - and make sure you have a grounded power cord on the thing for that matter. Also ohm the windings themselves - you should have at least 1/10th of an ohm through them unless they have burned up and shorted.

I am looking for such a grinder. If anyone has knowledge of one up for sale or of someone willing to part with one, please let me know. I am not very good at wiring so can't help with that!
Jim.