Trying to fix my grinding wheel....

[massimofinance]

This was my fathers grinding wheel and I really want to repair it. I know I could buy some garbage at home depot, but want to use the old retro well made tools. The wire was frayed from where it connects to the board. There is a switch. I bought a replacement cord and the replacement has three wires. For the life of me I cannot figure out how to connect the wires. Everything I try does not work. Some wire male connectors sticking out from the board have red or blue paint dabs.

It's an old general motors model. Any tips are appreciated.

 

[joed]

Re: Trying to fix my grinding wheel....

Some basic wiring info that should help solve the issue.
Green wire is ground. It connect to the metal frame of the unit.
Black wire is hot. It should connect through the switch.
White wire is neutral.

Not sure why there is a board in a grinding wheel. Can you post pictures?

 

[massimofinance]

Re: Trying to fix my grinding wheel....

Thanks a lot, here are the pictures. Any further help is appreciated.

 

[rockyrude]

Re: Trying to fix my grinding wheel....

there is a crimp-on/solder-on connector that you need to add to your new wires. if i understand the pictures correctly, the white wire connects to the blue dot and the black wire connects from the switch to the red dot.

 

[massimofinance]

Re: Trying to fix my grinding wheel....

Thanks very much- the replacement cord has a green cord and two white cords.

just so I understand: the replacement cord has 3 wires- one gree two white. green grounds on the frame of the grinder. one white goes straight to the blue dot on the board. The other white goes to the switch and to the red dot (I know you said black to the switch, but the replacement cord has 2 white wires).

Does the switch get grounded?

 

[rockyrude]

Re: Trying to fix my grinding wheel....

i have never seen a three wire cord with two whites, this isn't a 220v grinder is it? a 220v cord has one prong turned sideways. you can't use a 220v cord for 110v.

 

[massimofinance]

Re: Trying to fix my grinding wheel....

Hi, no, I bought a 110v replacement cord. It is a regular three prong plug where the middle plug is round.

 

[j_martin]

Re: Trying to fix my grinding wheel....

Does it hum when it doesn't work. Might have a bad starting switch. That's a split phase motor, with 2 windings. One is used for starting.

The start switch should be built into that board. It's operated by a centrifugal operator on the armature. Closed till speed is reached, then it opens.

 

[foodfisher]

Re: Trying to fix my grinding wheel....

If one of the white wires has some raised ribs running it's length, then that is the white/white the plain one is black.

 

[stackz]

Re: Trying to fix my grinding wheel....

Does it hum when it doesn't work. Might have a bad starting switch. That's a split phase motor, with 2 windings. One is used for starting.

The start switch should be built into that board. It's operated by a centrifugal operator on the armature. Closed till speed is reached, then it opens.

this. the backside of that board is the stationary switch. with as junky as it is inside that motor its probably fried. I had to replace one on a pool pump motor after bugs got in it and zapped it. did you not take pics of the wiring as it connects to the board?

if not, you will be playing a guessing game. at this point I'd just write the info on the motor down and go grab a new replacement from grainger for like $100-150

 

[bigdee]

Re: Trying to fix my grinding wheel....

You said it had a switch? where? How many wires are on it? can you post pics? Some old grinders had a MANUAL start switch that you held momentarily until grinder came up to speed. Can you check ohms between terminals 1&2 and 4&6....if I had to guess 1&2 is winding A and 4&6 is winding B. Was there anything connected to terminal 5? Most grinders do not have a centrifugal start/run switch but use a current sensing relay to drop out the start winding.

 

[massimofinance]

Re: Trying to fix my grinding wheel....

Thanks all for the help. The old wire was literally falling off the motor when I got it, so I never had a chance to write down what went to what. I bought a new switch and hooked it up, trying a few different combinations. None did anything. One makes the machine hum, but the wheels don't move. What does this mean? Hoping to get it fixed. Thanks.

 

[mla2ofus]

Re: Trying to fix my grinding wheel....

Does it hum when it doesn't work. Might have a bad starting switch. That's a split phase motor, with 2 windings. One is used for starting.

The start switch should be built into that board. It's operated by a centrifugal operator on the armature. Closed till speed is reached, then it opens.

I think J Martin has nailed down the problem you have. If it just hums the centrifugal switch isn't working as it should. Don't know what part of the country you live in, but that's just a 1/3 HP motor typical of what's used on swamp/ evaporitive coolers. If your local Lowes or HD carries swamp coolers they probably have that motor on the shelf and they're not too high priced.
HTH,
Mike

 

[bigdee]

Re: Trying to fix my grinding wheel....

. One makes the machine hum, but the wheels don't move. What does this mean? Hoping to get it fixed. Thanks.

That is a good clue. what # terminals did you connect to? I overlooked your third picture....that is not a very old motor (maybe in the sixties). Your motor is a 4-pole because the rpm is 1725 and it also has a start winding and a run winding. You found one set of windings when you made it hum. Do you have an ohmmeter? What kind of grinder is this?

 

[massimofinance]

Re: Trying to fix my grinding wheel....

Thanks for the response. It's a general motors delco grinder. I do not have an ohmmeter. No other connections get a hum or any kind of response. Yes, the 60s makes sense because my father came here in 1967 from italy. As for the # terminal, I have no clue. There are no real markings. Thanks again.

 

[stackz]

Re: Trying to fix my grinding wheel....

Thanks all for the help. The old wire was literally falling off the motor when I got it, so I never had a chance to write down what went to what. I bought a new switch and hooked it up, trying a few different combinations. None did anything. One makes the machine hum, but the wheels don't move. What does this mean? Hoping to get it fixed. Thanks.

humming like this?
http://www.youtube.com/watch?v=iDVLZ5RtRSo
have you tried spinning it manually like I did in the video? thats how I knew the stationary switch inside the motor was bad. and yeah, ignore the cockroach at the beginning, they are bad in my area and why my switch went bad :facepalm:

by the way, this is an example of what the backside of your stationary switch probably looks like. you cant really see it because its still mounted inside the motor.


the terminals you're looking at in your pics are the backside of this pic.

 

[j_martin]

Re: Trying to fix my grinding wheel....

Makes sense to me. The run winding would be on two of the terminals. The start winding would be on 2 (maybe one shared with the run winding) but connects through the centrifugal switch.
1. If it's smoky, or the thinner layer of windings is obviously burnt, yer toast.
2. Take the terminal board out. On the back side of it is a switch, probably coin silver contacts. You can file them clean if they are not completely fried. They are operated by a flying weight thingie on the armature, and are closed until the motor is spinning, then they open.

The motor type is called split phase induction motor. You can google it and get all the theory you want on it.

Even if you can't find a replacement switch, you can wire a double pole double throw switch to start it. You need one that latches one way, and spring returns from the other way. Center is off, spring end is start, and powers both windings. Stay on end is run, which only powers the heavier running winding.

Figuring it out without an ohmmeter would be durned near impossible.

 

[sschefer]

Re: Trying to fix my grinding wheel....

While I understand your reasoning for wanting to keep it and make it run, why don't you pay your dad a bigger compliment and follow in his footsteps. Bets are that he would watch the sales at HD and replace it with a Ryobi for 39.00 when they go on sale. I bought one a while back for sharpening tungstens when I'm TIG welding. I liked it so much I went and got another one to replace and aging sears model that was my dads. That thing had a 20amp motor on it and didn't perform any better than the Ryobi's.

Not saying Ryobi is a great product or anything but for the price it's darn hard to beat.

 

[bigdee]

Re: Trying to fix my grinding wheel....

Makes sense to me. The run winding would be on two of the terminals. The start winding would be on 2 (maybe one shared with the run winding) but connects through the centrifugal switch.
1. If it's smoky, or the thinner layer of windings is obviously burnt, yer toast.
2. Take the terminal board out. On the back side of it is a switch, probably coin silver contacts. You can file them clean if they are not completely fried. They are operated by a flying weight thingie on the armature, and are closed until the motor is spinning, then they open.

The motor type is called split phase induction motor. You can google it and get all the theory you want on it.

Even if you can't find a replacement switch, you can wire a double pole double throw switch to start it. You need one that latches one way, and spring returns from the other way. Center is off, spring end is start, and powers both windings. Stay on end is run, which only powers the heavier running winding.

Figuring it out without an ohmmeter would be durned near impossible.

The start windings will have a slightly higher resistance than the run windings. The difference in measured ohms is small but it will differentiate the two. The manual switch method is an alternative method that was once used on really old pedestal grinders. Another alternative is a current relay rated at 1/3 hp @115 volts. This motor has NEMA data on it so it is not all that old.

 

[massimofinance]

Re: Trying to fix my grinding wheel....

So I fixed it and thought I'd post as to how I fixed it. The buzzing sound was the engine trying to start! All I did was spin it, and it kicked right up. No problems now! starts fine now. I did not want to buy a new one ever and was going to fix my fathers tool no matter what. Thanks all who offered good advice!