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Grounding question, making a temporary table with saw horses

Posted: Thu May 23, 2019 7:01 pm
by Aaron W
New to welding, so I'm going to have lots of questions.

I was able to pick up a 19x26" piece of flat plate 1/2" hot rolled steel at scrap value which I am going to use to make a portable welding table.
Being new I already have few projects ahead of making a table (like a cart to make the welder more portable). In the mean time I was planning on making an adhoc table using the plate of steel over a couple of saw horses, or possibly putting it on an old metal shelving unit.

Am I correct in thinking that the connection between the table surface and the physical ground doesn't matter, only that the tabletop, work piece and the ground clamp have a good connection back to the machine?

I mean theoretically I could mount the table on power pole glass insulators or copper ground rods sunk 8 feet into the ground and it wouldn't matter so long as that ground clamp from the machine has a good connection to the table, right?

I have a lot of plans for the welder so would really like to not cut the relationship short by electrocuting myself. :D

Re: Grounding question, making a temporary table with saw ho

Posted: Thu May 23, 2019 7:06 pm
by cj737
Your ground clamp only needs a path to the work piece. If that is via contact with the table, then it's fine.

Re: Grounding question, making a temporary table with saw ho

Posted: Thu May 23, 2019 7:24 pm
by Aaron W
Thanks, thought so but less painful to ask, than to find out I was wrong.

Re: Grounding question, making a temporary table with saw ho

Posted: Thu May 23, 2019 8:53 pm
by cj737
Aaron W wrote:Thanks, thought so but less painful to ask, than to find out I was wrong.
Life’s best lessons leave scar tissue :D

Re: Grounding question, making a temporary table with saw ho

Posted: Thu May 23, 2019 10:12 pm
by weldin mike 27
You are correct, but be aware tat the optimum ground, or earth as we call it in Australia is directly to the part. The issue with being on a steel table that is grounded is that if there is a gap or dirt on the table top, the welding current has to jump across and cause an arc strike, that could be damaging to precision parts. Hope this helps

Re: Grounding question, making a temporary table with saw ho

Posted: Fri May 24, 2019 2:13 am
by tweake
direct to part is best. i have accidentally welded a part to the table before. nothing major but its another thing thing that needs cleaning up later.
the other way to to connect to a third hand (that has brass feet).

Re: Grounding question, making a temporary table with saw ho

Posted: Fri May 24, 2019 9:13 pm
by Aaron W
The welding class I took was held in a high school metal shop that was probably built in the 1950s. The stick weld work benches were pretty rough, and cupped in places so I have experienced arc from the piece to the table and parts sticking to the table a few times.

My first projects are mostly square steel tubing, so I don't think having good contact will pose a problem, but also easy enough to clamp directly to the part for these projects if it does become an issue. Only real benefit to clamping the table instead of the part is not having to clamp and unclamp the parts as I go. Pretty minor time advantage for one off parts I'm making for myself.


I am looking at other options for clamping when I get to some of my smaller, less conveniently shaped projects.

Re: Grounding question, making a temporary table with saw ho

Posted: Mon May 27, 2019 6:27 pm
by Aaron W
Well I ran my first current through the machine and neither the machine or my hair are smoking so that is a good sign.

The operator needs some work, but my first MIG welds don't look too bad and will only get better with practice. I clamped one leg of the work to the table with the ground clamp.

Thanks for the help.

Re: Grounding question, making a temporary table with saw ho

Posted: Wed May 29, 2019 6:43 am
by motox
make a third hand with copper ends. eliminates arc strikes

Re: Grounding question, making a temporary table with saw ho

Posted: Sat Jun 01, 2019 1:44 pm
by loudandgreen
I was about to ask a similar question. I'm glad there's quicker/smarter people. Thanks to the OP for beating me to it lol.