Spot Welds Not Holding

[offshores]

Trying to weld two pieces of sheet metal together and they're not holding very well. I'm using the lowest setting with the wire feed set at 7 with "Hobart .024 mig solid welding wire" with a copper backing. It's a lower end Craftsman Mig with gas and worked great for welding up thicker stuff. I've grinded and cleaned both sides of the sheet metal and am just wondering why it's not holding? Any advice for a newbie? I'm afraid to blow holes through the sheet metal and maybe I'm letting off the trigger too soon???

[Derek Cobb]

Sounds like a lack of penetration. Maybe turn the heat setting a notch higher.

Get some scraps of the same gauge steel and practice a bit adjusting the heat and the time. Thin stuff gets tricky.

Practice, practice practice

[offshores]

That worked way better, Derek. I turned it up to 2 and the bead actually laid flatter than before. When the setting was on 1 the bead was almost like a BB sitting there. I need to get some practice sheet metal, but I was welding on my apron today. Thanks

[Derek Cobb]

Should'a kept the old apron and cut it up for your practice pieces.

[offshores]

I actually cut a piece off the original apron, hammered a big dent out of it and welded it back on. I'm gonna post a few pics in hopes of getting some feedback.

[beetlenut]

Take some scrap of the same gauge and increase the heat until you blow through. Then back off to the next lower setting. Increasing the distance the electrode tip coming out of the gun is from the work is also a way to lessen the heat. Kind of like a fine tuning.
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[offshores]

^^^ that's brilliant. I really do need to get some scrap to practice on.

[oldmanmark]

good suggestions. as a trial n error welder myself getting dialed in is the difficult part. increase the wire speed at same heat setting makes a cooler weld. a cold weld is just a b.b. sitting on top. lower the wire speed same heat setting makes hotter weld. change the heat setting and depending on wire gauge and metal thickness probably have to fiddle with the wire speed again. i like beetlenuts suggestion. simple is good.

[aircooled356]

Here is what I ran into.
I was trying to spot weld thru a 1/8" hole to the parent metal.
The arc would start on the sheetmetal closest to the tip (path of least resistance) and not penetrate to the base sheet.
By increasing the diameter of the hole, the arc could "bridge" the two layers, fusing them together.

Hope this helps you.

[beetlenut]