Good Ground connections for welding

[Glenn]

When using a metal welding table, clamping the ground to the table work, and makes the entire table the ground. Place the work on the table, hit it with the stinger and go.

For some projects the current does not flow as well as I would like. What is your opinion of making a extension to go from the original grounding clamp to another (secondary) grounding clamp that can be attached directly to the project, or close to the weld zone? This could be nothing more than a set of jumper cables, clamp one end to the original grounding clamp and the other to the work.

Is this feasible to improve the grounding?

[agsolder]

Either way should work, clamping to the workpiece directly or to the steel table-- unless the workpiece itself is not getting good contact with the table. I think a jumper would add to the clutter, introduce new variables (ampacity? good connections?) that might even reduce amperage. Also, that mystery (to me, anyway), arc blow, can be a problem if your ground is too close to the stinger.

[evfreek]

Hi Glen. I think that this is a great idea. I will give it a try.

By the way, conductances add, so this will always lower the resistance. For example, adding pipes to a network (fully developed flow) always improves the rate. Note that this does not apply for incompletely developed flows, for example, adding extra inlets to a naturally aspirated burner.

The arc blow problem is a valid one. Still worth a try.

[Glenn]

I was thinking about two different applications.

One lack of good ground with the table due to dirt or whatever. Attach the extra cable and your good to go. A little help from a friend so to speak.

The other is if you are using some type insulating material between the work and the table such as rubber tires on a lawn mower being repaired. No use disconnecting the "good ground" to the table. Just add a jumper.

My concern was the way the electric flowed and if it would effect the weld or the welding machine. I never did understand how 4-5-or more welders could be connected to a common grounding clamp and one lead going to the work where several stingers were being used. (Large fabrication with several welders working at the same time). When ask how the electric found it's way back to the right machine to complete the circuit, I was told not to worry about it. (grin).

Again the jumper is NOT made from 18 ga lamp cord, but made from REAL welding cable, using REAL welding clamps.

[Covforge]

Don.t make a mistake and leave a grinder or saw where metal can contact the peice or table it will feed down the ground in the cord instead of the ground strap.
We learned the hard way. Fried a portaband.
Travis

[R Funk]

Covforge is exactly correct.

If you use a table for a ground make absolutely 100% certain that is a bullet proof ground from the table to the welding ground.

Or you might be a dissapointed owner of a power tool that used to work.

If the tool is grounded it may be an easier ground path than the table. Thus the 10 amp tool or whatever it is may see a full 150 amps of welding current releasing the factory installed smoke.

Please note: once the factory installed smoke is released it is almost impossible to re-install the smoke and make the tool run again.

The same principal applies if you are welding on a truck bed or other equipment that should be grounded and you lay a power tool down, creating an alternate ground path for the welding current thru the tool.

[irnsrgn]

using an extra ground with 2 more clamps is kind of over complicating things. just move the ground to whatever you are working on its so simple an answer.

[Glenn]

For some reason the welding table is not imparting good ground to the work

So, if the welder and the welding table are stationary (have not been moved is 6 months or more) would it be a good idea to run a grounding clamp to the welding table and bolt it to the table?

Or put a terminal on the end of a short piece of welding cable and bolt it to the welding table. The other end of the short piece of welding cable would have a quick disconnect to fit the welding lead.

I know, KISS and simple is best, and this is getting complicated real fast.

I have checked the lead connections (good contact at the welder, grounding clamp and stinger), used a grinder to get bare metal at the ground connection point, and even wire brushed the slots in the stinger. That leaves the problem at the table / project contact point. Or am I missing something?

[Hillbillysmith]

As long as the wire is heavy enough to carry the required amperage, it will be perfectly ok without dropping the amperage. I have a chart here somewhere that tells the max length for the max amps in both aluminum and copper wires. When i find it, I'll post the chart. It goes up to like 500 feet or something like that.

[jayco]

So you haven't moved the welder or the table in the past 6 months?
Nothing has been changed in the power supply to the welder?
Are you getting adequate voltage to the welder?

We once had a situation in which we thought every appliance in the house and my arc welder were on the 'blink'.......turned out the power company's transformer on the pole was going bad.

If the welder performs properly when the table is not involved with the circuit, one would think the table would be the problem.

"Resistance" could be part of the problem

If the 'route to ground' on the table is excessively long........and the table has sufficient mass, there could be problems.

Resistance is the main reason your not supposed to use a 500 ft. extension cord.

I would try the jumper and see if it helped........I don't think it could hurt anything, and might help diagnose the problem.