How to Weld a Root Pass and Why You'd Want To - Using Everlast's 300 Amp Stick Welder
Kevin is about to do something he really doesn't like: arc weld (stick weld). He's making a pedestal for his sculpture Wherever You Go, There You Are out of 1/2" steel plate, and needs to make sure the sculpture, which weighs 1100 pounds, is safe and secure.
The pedestal should weigh about the same amount, so cranes and steel-toed books will definitely be involved!
Kevin bought 4 4' x 8' 1/2" sheets of steel, laid them out on his lift table, cut out the panels, top and bottom with his Longevity 62i plasma cutter, picked them up with his gantry crane, got his angles right, and tacked them together to create the pedestal.
Now it's time to come in with a stick welder and some heavy rod and do the root passes, which will penetrate the thick steel and then be topped with welds he can grind for appearance sake.
A friend lent him an Everlast POWERARC 300, a 300 amp stick welder to do the job. "Oh boy!" says Kevin.
This powerful welder is the same size as Everlast's 255EXT TIG welder, but it has a different face. The front has a display screen and amp knob and some indicator lights. The display shows "on," "overtemp" and a "short" light. Below the amp knob is a hot start adjuster for amperage and an arc force adjuster to help with penetration.
Below that are hook ups for the ground, the positive for the stinger and a separate hook up for running 6010 rod, which will provide a little more power. The on / off switch is on the back.
Kevin is going to run some E7018 welding rod from Lincoln, which is 1/8" in diameter. The box says you can run the rod at 90 - 135 amps, so he's going to set the amperage at about 130.
The first pass is a little cold, so Kevin decides to turn up the amperage. The dial has no numbers on it, but this was about half on the dial, so he turned it up to about 3/4s. The amperage had dropped a little bit to 130, so he turned it up to 143.
He welds for just over a minute. The weld shows how Kevin wove back and forth, bobbled at one point, then wove nicely again. He's pretty happy with the beginning of the weld, but will grind down the area with the porosity and reweld it.
After this root pass, which makes sure the heavy metal plates are welded together, he'll come back with a solid pass with a MIG welder on the outside. He's already gotten the exterior weld finished and ground down smooth, and gotten his root pass inside the pedestal, which is good enough, since no one will see it. He turned the pedestal over so he can get his root pass on the next outside joint and the opposite joint inside.
Once that's done, he'll come back with his MIG welder and get a nice cover over the top of the root pass that he can grind down to get a nice rounded edge where the plates join. That's important for outside, which shows, but inside all he wants is penetration and strength.
Then Kevin will weld on the bottom. After that, it's time to weld on the top from the outside. He'll lay down the pedestal, climb in through the bottom and run his root pass inside. He'll also make sure he has plenty of ventilation, use a respirator and blow air inside to get the smoke out while he's working.
He used the stick welder to get better penetration on the thick metal. He wanted to crank it up and get some amperage going. He didn't push the machine beyond 143 amps, though, simply because the welding rod he is using isn't rated above 135 - he was running it a little hot as it was. That welder, though, can run 1/4" welding rod, if you have it, with no problem at all.
Kevin thanks his friend Art for the loan of the toy - he means tool! - and says he'll give him a good report. Now it's time for Caron to go back to work, so you have time to visit his site at http://www.kevincaron.com to see more how-to videos.
(You might want to take a moment, though, to hear Kevin speak in tongues ....)
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