# Testing Ground Of South Bend 13 Lathe



## toolman_ar (Jul 5, 2016)

I have a 1940, SB13, that I recently rewired from 440v to 220v.

While testing continuity and tracing wires, I testing the Green ground wire and found it does not create continuity to any part of the machine.

The wire is mounted inside the quick disconect mounting bolts. I don't get a tone even on the bolt it is attached to...

Should I move the ground mount to a different location?

or

Run a wire from the motor case to the ground on the power feed line?

toolman_ar


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## JimDawson (Jul 5, 2016)

I normally run the ground to the disconnect box mount screw, or in modern disconnects, to the ground lug.  Then from there I run a ground to the VFD (if used) and to the motor (from the VFD ground lug).  If you are using a line voltage motor starter switch, there should be a ground to that also.

If you don't have a connection at the disconnect switch, it time to go into it a bit deeper to find the break in continuity.  Right now it sounds dangerous .
.
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## toolman_ar (Jul 5, 2016)

Jim,
I looked tonight and found that with a gental pull the Ground wire popped out.

I tested the stud to the cast iron base and have continuity. 

I am going to get a star washer and proper cable end and reatach the ground.

Then test from motor housing to ground and see what I have. If needed I can add a wire directly from the motor housing to the disconect mounting bolt to tie the two together.


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## JimDawson (Jul 5, 2016)

Sounds like that will work   I normally like a ground wire attached directly to the motor also.  Just a little added safety.


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## toolman_ar (Jul 5, 2016)

My goal this week is to power it up to test and see if everything works. I did not get to see this lathe under power. So I am curious to see what squeaks or rattles.

I will most likely tear down and clean everything. At that time I will replace all the wiring. 

I need different heaters also.

Toolman_ar


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## dlane (Jul 5, 2016)

Clean/solder connections , di grease, shrink wrap, if that doesn't work, knock switch box a few times if that got her goin clean switch contacts
heaters?,
Got a pic of SB 13 ?.


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## toolman_ar (Jul 5, 2016)




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## toolman_ar (Jul 8, 2016)

I got the new cable end and star washers installed.

I can now get a good test from the motor housing, base casting, & motor mount.

This makes me want to test the other machines to ensure they have a proper ground.


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## ChrisW (Jul 8, 2016)

I don't know what your control voltage is, but remember to check your starter coil voltage.


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## jim18655 (Jul 8, 2016)

A word of caution - don't use the box mounting screw to connect the ground. It can work loose from vibration or changes in humidity and it's a NEC violation. Drill a hole in the side of the box, clean off the paint and bond the box to the equipment ground from the panel using a bolt. If there isn't a ground from the panel then the conduit is the ground. I would recommend a bonding bushing to make the connection to the conduit because the knockouts may not be rated for grounding if your voltage to ground is over 250 volts or the lockring could loosen up. This is only a problem on the 480 volt equipment.


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