Grounding an ungrounded motor.?

[whiteb01]

Is it as simple as changing the cord and running the ground wire to the motor housing?

[DLB]

Is it as simple as changing the cord and running the ground wire to the motor housing?

That is how simple it is on an early Mark. You are talking about a Model 10, right? If everything is metal to metal between motor and headstock that will work. Someone with a Model 10 will likely answer with whether it is better to attach the ground to the motor Vs. headstock.

- David

[whiteb01]

Is it as simple as changing the cord and running the ground wire to the motor housing?

That is how simple it is on an early Mark. You are talking about a Model 10, right? If everything is metal to metal between motor and headstock that will work. Someone with a Model 10 will likely answer with whether it is better to attach the ground to the motor Vs. headstock.

- David

It is a Model 10ER. I've taken it apart and everything seems to be metal to metal.

Thank you.

[JPG]

Two devices may create a shock hazard - motor and power switch.

I would direct wire the power cord ground to the motor and a jumper from the same attachment point on the motor to the headstock (or a large(1/2") ring connector around the switch mounting shank).

The added jumper eliminates possible conductivity failure through all the interfacing surfaces between the motor and the switch. The ring connector eliminates conductivity failure between the switch shank and the headstock.

A switch with a plastic mounting shank eliminates the need for the jumper.

[chapmanruss]

When I restore a Model 10E or 10ER I end up replacing both the switch and the power cords. I have not done as JPG suggests only because there is barely enough room on the switch threads to have the on/off plate and the nut. The Headstock casting is simply too thick to add additional washers or ring connectors. I do replace the power cord all the way into the motor and add the ground there. Being that the Model 10's are all metal it will ground the entire unit.

[jsburger]

I do the same as Russ (almost). The cord is replaced all the way to the motor and the ground wire is brought out with a ring tip and attached to one of the motor mount bolts. The paint is removed from the motor mount flange and the SS motor mount casting in that area. I check resistance from the ground wire to the quill shaft to be sure everything is grounded. As Russ said, the entire model 10 is all metal so there should be no problem where the ground is attached. Grounding directly to the motor should not be a problem unless paint gets in the way between the motor mounting flange and the SS motor mount casting.

[whiteb01]

I replaced the cord all the way to the motor. Pulled the motor apart and cleaned it good while I was at it. I grounded to the motor mount. Thanks all.

[NewfieDawg]

Glad I dropped in today. I have a 1958 Greenie that I bought as a basket case. The seller told me that the motor (a GE 3/4hp DoM circa 1956) ran OK, but he had hooked up a different capacitor that was resting on the motor and the motor pan. To make a long story a little shorter, I've replaced the bearings on the motor, the quill and the Gilmer drive shaft. The cord on the unit is your basic 50s type two wire cord. I was going to replace it with a 16 gauge 3 wire cord. I'd figured that I could tap a ground screw onto the motor body. Was not aware the I may need to run a jumper to the switch though. It has been a learning experience. Grew up using a 10-ER that Dad traded up for back in 1961. Then he traded up for a MKV in 1981 which I am still using. The Greenie will get put back to work after I finish cleaning up the bench and way tubes.

[beeg]

Use at least a 14ga replacement cord.

[DLB]

...I'd figured that I could tap a ground screw onto the motor body. Was not aware the I may need to run a jumper to the switch though...

Standard OEM wiring on grounded Mark 5/V is a ground connected to the motor body only, no jumper to the switch. When everything is assembled the metal parts are grounded via metal to metal contact. I think the jumper suggestion you refer to was specific to the Model 10 family. As mentioned above, going smaller than 14 AWG can cause or contribute to startup problems.

- David