View Full Version : Got the welder pedal done. Grounding question.

10-03-2005, 09:22 PM

I talked to Kevin at Stumpfh welding and he was real clear about how the pedal hooks up to the plug-in. He even went and looked at one in the shop and actually called me back http://bbs.homeshopmachinist.net//eek.gif The wiper goes to the center prong ant the taps go on either side depending on the way the pot is mounted (rotation). That deal on the right is what turns the arc on and the pot controls the current.

I guess I'll fire it up tomorrow with my C25 tank and try welding some steel. This has been a cool project for me!

About the ground... The pedal has a 2 prong plug that is just the arc on/off switch and it has a separate 3 prong plug for the current control that goes straight to the pot. The old Miller pedal that I modified had a 4 prong plug and one wire was grounded to the pedal.

I went ahead and screwed the green wire to the pedal and when I wired in the new plug (I had to change the plug and receptical because I couldn't find anything that would plug into the receptical that came on the machine) I pulled the green wire out to ground it to the machine.

The thing didn't come with the pedal grounded but it was made in 1970. I'm not sure if the pot is grounded to the chassis like one on a car but maybe I should check...

Any advise on this ground deal?


That's the inside of the beast. As soon as I get all the mechanical/electric done I'm going to paint it. Grey or Red? It is a Lincoln but this model came grey.

Sorry for the long post...

[This message has been edited by hoffman (edited 10-03-2005).]

10-03-2005, 10:22 PM
Hi Hoffman,

I don't see any problem with grounding the pedal. Make sure none of the leads to the rheostat are grounded, since your other schematic shows them all floating.

Leigh W3NLB

10-03-2005, 10:27 PM
Thanks Leigh. What do you mean by floating? I was going to check continuity between all the leads and the chassis.

It wasn't designed with a ground so I'm a little spooked about hooking up things I don't understand.

The little dotted lines on my schematic were just showing where wires shot off to another part of the circuit. I'm not sure if that may have mislead you.

[This message has been edited by hoffman (edited 10-03-2005).]

10-03-2005, 11:14 PM
<font face="Verdana, Arial" size="2">Originally posted by hoffman:
Thanks Leigh. What do you mean by floating?
...The little dotted lines on my schematic were just showing where wires shot off to another part of the circuit.</font>

Floating = not grounded. From your basic schematic it appears that all leads to the remote control have or can have voltage on them relative to the grounded cabinet. I was just suggesting a test to make sure none of these were inadvertently grounded.

I assumed that the dotted lines went to undefined circuitry.

Leigh W3NLB

10-03-2005, 11:26 PM
Thanks a lot Leigh. I understand what you're talking about now. I guess it's common for rheostats to be grounded through the mounting stud. I think the friend I had helping me on this one checked that and said that it wasn't grounded.

So if I double check and none of the leads are grounded to the pedal or machine chassis I should be OK to run a separate ground?

It seems pretty strange to me that Lincoln wouldn't have ANY grounding of the pedal even considering the machine was built in 1970.

The later models have a 5 pin connector that screws in and the screwed plug provides the ground via a sort of cable shield arrangement. I think what I'm wanting to do would accomplish the same thing.

Thanks again, I envy you electronic guys!

I just re-read and I'm confused by :

"all leads to the remote control have or can have voltage on them relative to the grounded cabinet"

What do you mean by "Relative to"?

Does that mean that the ground could have a function in the circuit besides just providing a pathway for any electrons that may try to get me!

[This message has been edited by hoffman (edited 10-03-2005).]

George Barnes
10-04-2005, 12:27 AM

It sounds like you are a little ahead of me on this electricity deal, so I'm not sure from your post if this is relavent. The red piece shown in the pic I posted is some sort of micarta like material. That is what the pot is mounted on. So it would appear that the pot is not grounded to the box.

10-04-2005, 12:41 AM
Don't worry about it, If it isn't grounded properly you'll know it.

10-04-2005, 08:49 AM
Is there any danger of the grounded pedel forming a circuit from the torch thru Hoffman to the ground? An old metal cased, gounded drill nearly got me once. An extension cord got wedged in the steel frame of a building I working on and made the whole building frame hot. I was on a stepladder with the drill in one hand and grabbed the steel to steady myself with the other hand. Ouch! The ladder was a 6 footer and there was nothing sharp around the base where I landed. If I hadn't fallen I think would have been stuck there until my heart Stopped. Grounds are not automatically good.