A bit OT, but I figured I would ask a quick question for you far more experienced welders...my bench top is solid aluminum. Can I ground my welder to it when welding steel? How about the steel frame of the table?
It may get a little hot and if your part is not well grounded to the table it may even burn holes in it.
I wouldn't. If it arcs between the aluminum and the object your welding it will pot mark your aluminum top. Hook the ground to what your welding for best results.
But there is no conductivity issue or reaction I need to worry about? As for grounding the part to the table, would the chance for burn through be the same as with steel if poorly grounded or more since its Al?
It all depends on the surface of the piece your sit on the table. If it is nice and flat, heavy and has good surface contact then you'll be fine. If you have a piece that sits up on sharp points then you might have a problem. I have an aluminum plate I often set up work on to be welded and I clamp to it not the work piece, but I do clamp the work piece to the plate - that why I use it as it is set up for clamping smaller pieces for precise welding. Every now and then I run a large DA over it to clean it up. Don't use an anodized plate, won't work that.
Well you are not going to have a problem with conductivity at all aluminum is a good conductor. You won't get aluminum transfer to the steel if that is what you are wondering, we used to use aluminum sheet between the electrodes and the steel when spot welding to keep the steel from blowing out at the spot weld. Aluminum and steel melt at very different temperatures, approximately 1200 degrees for aluminum and 2700 degrees for steel. If you get a liquid pool in your steel the aluminum will already be on your foot and burning a hole in your sock. What normally happens when you are using an aluminum table top that is your welding ground for steel is that places where the steel is not making good contact the aluminum will blow out or pit.
In my experience dirt will be your issue. Normally small Pieces of metal or dirt will prevent a good ground to your piece. This will force the steel to focus in a very small area of the table and cause a divot burn on the aluminum.
Thanks for all the input fellas. The aluminum top IS anodized...so that obviously changes things. Looks like my best bet is to simply ground to the work and if the work is small, use a plate like oj mentioned...I don't want to ruin my work surface!
Anodized is not good. Even with the table grounded to the welder, I run a 10ga wire with allagator clips to the material and table as backup, sometimes there is no place to hook the normal ground clamp to it or it has to move into differernt posissions
Whether you want to or not you will ruin an anodized surface when you use it for a welding surface. Even if you ground the metal you are working on. Anodizing is a surface finish, you will scratch the hell out of it when moving around welding projects and you will burn spots into the surface from hot welding spatter balls. Anodized aluminum is NOT what I would use as a welding table.
Sometimes you can become the ground if the current is looking for a place to go. I like to use the work piece whenever possible. Small pieces, I've bolted to bigger pieces for a real solid ground.
Just make it a habit to always ground as close to where you're welding as possible. Someday the current may take a path you hadnt planned on, like through a bearing or arc through a small gap etc and cause you other problems. Good Luck.
I always like to put the "ground" as you call it on the part that I am welding and as close to the weld as possible. It's called the "work lead" not a ground.
Well electricity does take the path of least resistance, we are made mostly of salt water and salt a water is an excellent conductor.
Give up on keeping your Aluminum top pristine especially when you weld on it. My fabricating table has a thick steel plate top and when the welding "BBs" get in the way I grab a grinder with flap wheel and dress it down. I attach the negative lead as close to the part being welded as I can and I keep a wire brush handy to clean off the area where I attach it. I'm not a pro by any stretch but my work is pretty good.
I was welding outside under a race car on jackstands one damp night. I was laying on my back on a cement driveway. As soon as I struck an arc I felt a trickle of current between me and the ground. The car had a ground cable attached to it. Grabbed a piece of plywood, laid on that and all was well.
I was welding boat trailers in the mid '70s in a factory that had mostly buzz boxes, we had welding screens between the jigs and all the jigs were linked by grounding straps so that you could string a lead to any jig in the shop if you wanted to. One day this fella was welding spindle ends into the axles and decided that he was going to sit down so he found this metal stool. Once we all cranked up I heard this war whoop and we all stopped to see what was wrong. Burned his butt pretty bad.
Two issues I had welding, both TIG and both on aluminum. First, about 7 years ago, after welding for about an hour, I looked at my digital watch, the time was something like 57:84. The watch was toast. I wear hearing aids and last year I was welding a piece and when I was finished I noticed a loud hissing. At first I thought there was a leak in one of my air hoses. I looked all over my garage and then removed one of my hearing aids and the hiss went away. I talked to the tech at the company and he told me that it was probably the high frequency from the welder that toasted it. We gotta be careful and make sure all our equipment is properly grounded including welding benches.
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