Hot Rods How are these two plug welds?

How are these two plug welds?

 

Besides a bit blurry they look ok to me although I am not a certified welder. I just stick stuff together with the "hot glue gun".
I'm not sure what you welded together I'm going to assume it's sheet metal and if that's the case it doesn't take much to get them to stick together a plug weld just needs to penetrate the bottom piece of metal and stick to the top piece of metal. If you plug welded something heavier I would look at the back side and you can kind of tell how good of penetration you got just by the color change on the back of the metal you welded into.

 

Can't tell from this side. Sometimes a plug weld will just fill the hole in if it does not penetrate to the other panel.

 

I would say they are cold.

 

I’d have to see the backside to let you know if it’s good or not.

 

Looks alittle cold but filling a sheet metal hole usually has to be alittle on the cold side.
Yes show the back side. consider using a piece if brass or copper as backing when welding a large hole.

 

Not able to see the backside here. Does the 360 ring around the spot weld indicate that weld did not go to the shoulder?

 

Could be that the parent metal was just slightly melted at the edge of the bead, creating a very narrow dip. As everyone has said, after the bead is done, there’s no way to tell without looking at the HAZ on the back side.

 

Should these plug welds be grind down smooth or left in the current state?

 

Where is this located on that car? Will it be body-worked before paint? Is it structural?

 

Rear quarter to door jam. Not sure what you mean by body work before paint. Please explain.

 

You asked if that should be ground flush or left as is, so I mean is this area visible to the operator once the car is fully painted and assembled? If so, then I'd recommend sanding flush to make it easier to prime and paint over later without showing a hump. If it's totally hidden, I'd leave as is and move on

 

The strength in a (properly done) spot/plug weld is down between the two layers of steel. Anything that sticks up above the top layer is not adding any strength. Go ahead and grind it smooth.

 

This is the backside of my plug welds, which I'm fine with

 

Here's some plug welds I did while grafting lengths of 2" x 3" rec steel together for my roadster frame. I overlapped the tubing and backed it with 3/16" plate then plug welded them. I plugged 'em hot!

 

They taught us in the collision repair business to make a test panel or two of the same materuial you will be welding and then destructive test them

This rings especially true, IMO, for a novice that isn't sure of the quality of their welds. I would recommend doing some test panels before welding on the car. You'll either find out you need more practice, or you're good to go, rather than hoping or guessing

 

Had to do this in a couple different GM and Chrysler classes to get certified for frame and structural repair. We'd weld small panels together then hook up chains and pull clamps with a pressure gauge and start pulling. We had to hit so many pounds of pressure before our welds broke or the metal ripped to pass the classes and tests. We did plug welds and seam welds.

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