Need some tips on welding sheet metal to 3/8 plate

I have a couple pairs of prefab metal legs that are meant for mounting to a wooden top. I'd guess that the metal on them is 14 gauge. I'm thinking of using them for a small 3x4 welding table using 3/8 plate. So far my practice has been limited to pretty thick stuff. 3/16 and 1/4" thick scrap. What's the preferred method of welding sheet metal to a thick top. It would be a fillet type weld. I thought about trying to weld around the provided bolt holes since that is where it's designed to be attached to something, but I've not tried welding anything this thin before.

What do you suggest?

Ian

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I'm not sure you would need to 100% weld. Weld fully around all the corners and then weld 1" or 2" beads down the sides.

So do I use small rod and amps, or what I would use for 3/8 metal? Maybe I need to come up with some sheet metal to practice on.

Ian

I'd use 3/32 6013 or 7014 for this. Run about 70-80 amps, fairly quickly, but not too quick. Weave a little if you like.

I don't have much stick experience, but I welded the top on my table (14ga) with 3/32 7018AC at about 85a with little trouble. 14ga isn't really 'thin' as for as sheet goes, so it's a lot more forgiving than you're expecting it to be.

what sean said is good advice, though. you only want to weld about 1" long beads every few inches or you'll warp the plate. something else you may want to consider is putting some square tubing across the other direction to support the plate if you're going any more than 2 or 3 feet. 3/8" is fairly thick, but it's still just plate and it will flex.

I had planned on welding 3 pieces of 1/4"x2" flat stock on edge length wise down the underside of the table for stiffeners. One about 3" in from each edge and one down the middle.

thanks for the advice,
Ian

That sounds like a good idea, that would give you more strength and something to weld to. I've looked at those legs at Northern Tool and been thinking about building a table using them as well. Post some pics when you are done!

Will do, but it will be a bit I expect. There's a few irons in the fire. I have a couple leads on acquiring the plate, but haven't followed up on them yet.

Ian

I would use a simple plug weld on the existing holes, fill them up but keep the heat concentrated on the heavier 3/8 plate. There are more than enough holes to do the job, later I would add some sort of spacer support at the bottom of the legs between them to keep them from tilting.

What do you mean by spacer support? I was going to put a shelf underneath to hold welder and accessories.

Ian

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Originally Posted by Haywire

Will do, but it will be a bit I expect. There's a few irons in the fire. I have a couple leads on acquiring the plate, but haven't followed up on them yet.

Ian

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If you have a scrap yard close by, lots of time steel companies will have drops and sell them for scrap.

I would recommend using a rod such as 6013 or 6011. You could use 3/32" or 1/8" if heat is set right. The 6013 does not penetrate very deeply so you won't melt in and ruin the edge as quickly. The 6011 is a better penetration rod, and has a great fast freeze capability, that will give you some leeway. Also, you probably know to keep your heat more angled toward the heavier plate. Your angle of your rod will affect the melt in also.

Quote:

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Originally Posted by Haywire

What do you mean by spacer support? I was going to put a shelf underneath to hold welder and accessories.

Ian

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A shelf that goes from one leg side to the other would maintain the space between the legs and give it stability, good idea adding the shelf.

what I've learned works welding sheet to heavier metal with 6011 is to run a bead an electrode width away from the thin metal pointed straight at the thick metal, then just whip the rod over at the sheet to tie it in. I think I was weaving a bit on the bead sorta like this vVvVvV. it comes out as an even bead if you get it timed right.