Getting started with O/A

[jimgood]

Originally Posted by olcarguy

Rebar is hard to weld at the best of times, made with cheap **** steel. Get some pieces of scrap plate or sheet, not galvanized, and try that. Cut some blanks about 2" by 4" try putting a bead down without using any filler. When you have mastered that try a t joint and a lap joint.....

That's kind of what I fugured. I just wanted to try my first weld on the cheapest scrap I had. Even with the #0 tip, I was able to melt chunks out of the rebar. It was 3/8" rebar BTW.

[jimgood]

If anybody has time, please check the weld at the bottom of page 3 of this thread. I'm quitting for the day, but I'm going to practice some more tomorrow. I have some more 1/8" sheet I can practice on.

[weldtoride]

Your welds are looking good. It looks like you have good torch control. When your welds on the rebar cracked, had you cooled them, or did you let them air-cool?

Your butt weld on 1/8 steel looks good from the topside, too. As for the penetration, are you using filler rod, and ifso, what size? A too-large rod can cool the puddle. If you are butting it without any gap, you shouldn't need much filler at all.

Originally Posted by MAStuart

Please dont weld or heat things on cement. It can explode .

Ditto, it can turn any moisture to steam, there is always some moisture in concrete. You have molten steel in the 1500 degree range and water boils at only 212, so more than enough heat. Welding on concrete can pop half-dollar sized chunks loose, they don't just come loose, they are steam-powered and moving fast. Invest in a few firebicks, they should be less than $2 each. (Regular brick has the same safety issue as concrete.)

Keep asking questions, and keep reading, especially about safety concerns, some aren't so obvious, like the concrete issue.

[chopperrr]

Originally Posted by weldtoride

Ditto, it can turn any moisture to steam, there is always some moisture in concrete. You have molten steel in the 1500 degree range and water boils at only 212, so more than enough heat. Welding on concrete can pop half-dollar sized chunks loose, they don't just come loose, they are steam-powered and moving fast. Invest in a few firebicks, they should be less than $2 each. (Regular brick has the same safety issue as concrete.)

Keep asking questions, and keep reading, especially about safety concerns, some aren't so obvious, like the concrete issue.

Wow, good to know this. I read a few books but they did not mention this. Thanks guys!v Good thing nothing happened so far...

[jimgood]

Originally Posted by weldtoride

Your welds are looking good. It looks like you have good torch control. When your welds on the rebar cracked, had you cooled them, or did you let them air-cool?

Thanks. On the rebar, I only let it air cool for a couple of minutes then ran water over it. It just occurred to me that by welding on top of the cement, the moisture was probably steaming up into and around the weld area. That probably doesn't help. The block was very damp.

Originally Posted by weldtoride

Your butt weld on 1/8 steel looks good from the topside, too. As for the penetration, are you using filler rod, and ifso, what size? A too-large rod can cool the puddle. If you are butting it without any gap, you shouldn't need much filler at all.

I wasn't using any filler. The two pieces were stock 1/8" x 3" and their was very little gap between them. I was forehand welding with the torch at about a 45 degree angle and the cone about 1/8" from the seam. The cone was about 1/4" long; very well defined.

When I first started, I was only letting the weld pool get about 1/8" in diameter before I'd start to move it. Sometimes it would split along the seam and I'd move the torch around trying to herd the two pools back into one. By my third try, I was letting the pool get to about 3/8" before I'd start to move and it was better.

[jimgood]

Today I'll cut up that 1/8" x 3 stock into more pieces and practice some more. I need to get some clamps. I was relying on the length of the stock to balance the pieces on the cement block and allow the weld area to hang out in mid air. But I've played that hand and, once I cut up that stock, I'll have to work with shorter pieces.

Goals for today: Butt weld with good penetration and minimal distortion. Yesterday I just plowed along the seam. Today I'll try spot welds at each end and the middle. Then I'll gradually fill in between.

If I get good at that, I might try to do it with the work piece vertical.

And if that goes well, maybe I'll try some other joints.

[weldtoride]

Originally Posted by jimgood

Thanks. On the rebar, I only let it air cool for a couple of minutes then ran water over it. It just occurred to me that by welding on top of the cement, the moisture was probably steaming up into and around the weld area. That probably doesn't help. The block was very damp.

Try your destructive weld test again without quenching, I think you will get different results. Even though the steel has lost its color, it is still is affected by the rapid cooling. I don't think the ambient moisture while welding is a metalurgical concern.

[jimgood]

Originally Posted by weldtoride

Try your destructive weld test again without quenching, I think you will get different results. Even though the steel has lost its color, it is still is affected by the rapid cooling. I don't think the ambient moisture while welding is a metalurgical concern.

Thanks. I'll try that later.

[jimgood]

I finally got a sound weld, but I had to weld both sides. Again, this is 1/8" x 3" steel, butt joined with no filler.

My first try resulted in a lot of burn-through.

I then broke that apart and flipped the two pieces around so I had fresh edges to work with again.

Below is my second try. I was less aggressive, though I still managed to burn through one spot. Most of the weld did not penetrate fully. I flipped it over and welded the other side. Then I took it to the anvil and bent it 90 degrees. It's not a sharp bend, but I'm pretty sure it will hold.

I also am struggling with the ends of the seams. You can see at the bottom where I completely melted away the metal, leaving a gouge. Need to go back to David's DVD. He addressed how to control that, if I recall correctly.

Left is convex side of the bend, right is concave side. The split at the top of the left picture is just because I didn't weld that spot.

[MAStuart]

Keep practicing . You will be good in no time. Get some filler rod and go back to where you are about melting through and start to add a dab of filler rod and you should be getting full penetration. mark