8” Dayton grinder issue

[goodshow1923]

Hey all. As some know I picked up an 8” Dayton grinder. The outward appearance was very nice. However it did run rough (see yesterdays post). Anyway I took a chance and picked it up. Sure enough bearing on the left side was shot. A new bearing later and the machine just hums. I can see it try to turn from torque but just won’t go. I tried to help it by hand still no luck. Everything is smooth and aligned when spinning by hand but still nothing.
I used wd 40 to get it apart. Is it possible I soaked something I shouldn’t have? It’s model 4z909b. Any help is appreciated.

 

[LopezBart]

start capacitor disconnected? Or problems w/ switch on start winding?

 

[goodshow1923]

start capacitor disconnected? Or problems w/ switch on start winding?

Thanks Lopez. I’m in the bottom now. Trying to figure this out without a diagram. Looks like power goes to the start winding switch then to the capacitor. So I’m thinking I should get 120 out of the start winding into the capacitor and then out of the capacitor to the coil. Does that sound correct? Sorry, hope that wasn’t too confusing.

 

[exmaxima1]

Is the bearing fully seated? If there is any binding the grinder may not have enough start up torque to overcome it.

Also, is there any chance that you reversed the polarity of one of the windings? If it's a 120/240 voltage model there will be 2 sets of windings that must be configured correctly.

 

[goodshow1923]

Thanks Lopez. I’m in the bottom now. Trying to figure this out without a diagram. Looks like power goes to the start winding switch then to the capacitor. So I’m thinking I should get 120 out of the start winding into the capacitor and then out of the capacitor to the coil. Does that sound correct? Sorry, hope that wasn’t too confusing.

Ok. I have 120 coming out of the winding. 120 into the capacitor but 43 coming out. I assume the out should be the same as the in?

 

[goodshow1923]

Is the bearing fully seated? If there is any binding the grinder may not have enough start up torque to overcome it.

Also, is there any chance that you reversed the polarity of one of the windings? If it's a 120/240 voltage model there will be 2 sets of windings that must be configured correctly.

They both look to be evenly seated. I didn’t get into the electrical. I simply removed the “armature” and replaced the bearings. Went back in the way she came out. And feel free to speak in basic electrical because that is one thing I know little about.

 

[RTM]

Got an meter which will test capacitors? Maybe the cap took affront to your fixing the bearing and decided it was his day to die. (I'll show him)

 

[micromind]

Did the rotor (armature) get installed backward (right is left and left is right)

The way to tell is when you spin the nut in the direction of rotation, it should loosen. If it tightens, it's backward.

 

[micromind]

If you power sit up and spin the shaft, does to run ok?

 

[goodshow1923]

If you power sit up and spin the shaft, does to run ok?

No. Tried helping it out but no luck.

 

[goodshow1923]

Did the rotor (armature) get installed backward (right is left and left is right)

The way to tell is when you spin the nut in the direction of rotation, it should loosen. If it tightens, it's backward.

Gotcha. No I marked it before the tear down. Nuts are correct as well

 

[goodshow1923]

Got an meter which will test capacitors? Maybe the cap took affront to your fixing the bearing and decided it was his day to die. (I'll show him)

RTM should I be getting the same voltage out of a capacitor as in? I would assume if anything it should be a boost right? I’m getting 120 In and 43 out.

 

[micromind]

Is it 115/230 (120/240) or 115 (120) only?

What is the rating on the capacitor (especially MFD (µfd)?

 

[goodshow1923]

115 only. Capacitor shows 150 mfd

 

[micromind]

That means the motor is almost certainly capacitor-start and not permanent-split capacitor.

Being single voltage, there should be 4 wires coming from the motor into the bottom part of the grinder. 2 of these are the run winding, the other 2 are the start winding.

Most likely, the white wire of the incoming cord is spliced to 2 of the winding wires, one end of the start and one end of the run.

The black wire of the incoming cord should go to one side of the on-off switch.

The other side of the on-off switch should go to the other end of the run winding and very likely one side of the capacitor. The other side of the capacitor should go to the centrifugal switch which is inside the motor. The other side of the centrifugal switch will go to the other end of the start winding.

If the above is true (it might not be, there's more than one way to start a single phase motor......) then it is likely that either the centrifugal switch is stuck and does not energize the start winding or one of the winding wires got broken during the disassembly/reassembly process.

The test;

Unplug the cord. Withe the switch off, set your meter to 200Ω. Short the probes together, it should read less than 2Ω. Now, read resistance across the 2 prongs on the cord. It should read open circuit (most meters will read O/L). Now turn the switch on. The meter should read something less than 50Ω. If it still reads open (O/L) then the run winding is open somewhere.

If it reads less that 50Ω, remove one of the wires from the start capacitor, preferably the one that goes into the motor. This should have no effect on the resistance reading. If the resistance increases, the start capacitor is shorted.

If the resistance stays the same, then read resistance from both cord prongs at the same time to the capacitor wire that goes into the motor. If it reads open, then either the centrifugal switch is stuck open or the start winding is open. If it reads low resistance then something else is wrong and we'll need to dive a bit deeper into it............

 

[goodshow1923]

That means the motor is almost certainly capacitor-start and not permanent-split capacitor.

Being single voltage, there should be 4 wires coming from the motor into the bottom part of the grinder. 2 of these are the run winding, the other 2 are the start winding.

Most likely, the white wire of the incoming cord is spliced to 2 of the winding wires, one end of the start and one end of the run.

The black wire of the incoming cord should go to one side of the on-off switch.

The other side of the on-off switch should go to the other end of the run winding and very likely one side of the capacitor. The other side of the capacitor should go to the centrifugal switch which is inside the motor. The other side of the centrifugal switch will go to the other end of the start winding.

If the above is true (it might not be, there's more than one way to start a single phase motor......) then it is likely that either the centrifugal switch is stuck and does not energize the start winding or one of the winding wires got broken during the disassembly/reassembly process.

The test;

Unplug the cord. Withe the switch off, set your meter to 200Ω. Short the probes together, it should read less than 2Ω. Now, read resistance across the 2 prongs on the cord. It should read open circuit (most meters will read O/L). Now turn the switch on. The meter should read something less than 50Ω. If it still reads open (O/L) then the run winding is open somewhere.

If it reads less that 50Ω, remove one of the wires from the start capacitor, preferably the one that goes into the motor. This should have no effect on the resistance reading. If the resistance increases, the start capacitor is shorted.

If the resistance stays the same, then read resistance from both cord prongs at the same time to the capacitor wire that goes into the motor. If it reads open, then either the centrifugal switch is stuck open or the start winding is open. If it reads low resistance then something else is wrong and we'll need to dive a bit deeper into it............

Micromind thank you so much for that lengthy tutorial. Everyone on this forum has been nothing but helpful. But that is above and beyond. This newbie certainly appreciates it. Especially on the electrical side. With your help I had the confidence to dive a little deeper into the wiring. Fortunately for me it was corrosion, I assume, on the capacitor leads. I cleaned everything up and put back together and she fired up. Still has a slight noise while running. It was getting late and was happy to see it up and running. I will be working more with it today. I can’t tell you how happy I was/am when she came to life. I have a few other projects to attend to today but hope to clean her up a bit more. If so I will post some pics to a new thread. Thanks again all, very appreciative.

 

[micromind]

I'll go ahead and speak for the majority of us here.......I really enjoy helping someone through something somewhat complex and hearing that it worked. There's something magical about it that I just can't describe.