Spot welds not "sticking".

[rennch]

Hi all,

I'm doing some spot welding. I have my top piece drilled out, both surfaces prepped, and I'm having a hard time getting them to "take". I fill in the hole on the top piece, but don't seem to be getting enough penetration on the bottom piece. They are just popping apart when I release my clamps. Do I need to increase the voltage? Wire speed? Gas? All of the above?

Thanks!

[kcpaz]

probably need more heat. Also, how big is the hole in the top piece? Make sure its big enough so the weld can melt the two pieces together before the filler material fills the hole.

[rennch]

They might be 1/8". Maybe a little bigger. I'll check that.

Thanks.

[Bobboloo]

Are you spot welding or are you plugging the holes from spot welds with mig welding? It sounds like you are plug welding with a mig welder.

Which ever is the case go to this welding website and post a picture of your weld and they will tell you exactly whats going wrong.

http://www.weldingweb.com/forumdisplay.php?f=6

[rennch]

Bobby,

I guess I'm plug welding with a MIG welder. I'm going to bump up the amperage and enlarge my holes a little, and see how I fare.

[TimT]

plug weld from the bottom up......start your puddle on the bottom ply, and weld out of the hole

[Jeff Hail]

Are you MIG welding or flux core welding? Are you MIG welding with a converted flux core welder? Make sure the guns polarity is correct.

[Porsche_monkey]

More current is likely required. And, although it's counterintuitive, less stick-out means more penetration.

What gas are you using?

[john walker's workshop]

too much wire speed and/or not enough heat. my welder has wire and heat dials 1 to 9. if the heat is on 8, then i usually keep the wire speed down a bit from there, like 6.5. use the trigger to time the spots, not the automatic adjustment if it has one. you probably need 2 to 3 short welding times to fill each spot if the heat is up, so you don't burn through. continuous is risky on sheetmetal.

[jpnovak]

Compared with welding sheet metal you need to crank the voltage all the way up. the plug welds are usually supported by a seam and all the surrounding metal that transfer the heat. I bet you are not getting hot enough.

Also try a slightly larger drilled hole (I use 3/16") to allow you to strike the arc on the back section of metal and then connect the top section of metal and lastly fill the hole. You will want to weld the perimeter of the hole and then end in the center. Make sure you weld slow enough for the two sections to weld together.

[TimT]

crappy pic of a pan replacement we did

to allow you to strike the arc on the back section of metal and then connect the top section of metal and lastly fill the hole.

yes strike the arc on the bottom ply and weld out..
as mentioned before

[dvkk]

I have a short piece of ¼x1 copper flat bar that I clamp to the underside of the piece without the hole. That way you can really crank up the heat and not blow through.
I also use the copper bar, when I have access, when I am butt welding. This prevents warpage even with really high voltage settings.

[haycait911]

5/16" hole is industry standard for panel replacement of 20 gauge steel. 3/8" for 18 gauge. start in middle of hole, once you have a puddle started, run clockwise around the perimeter of the hole, just inside of the hole edge. I usually go around twice to get a nice, hot, flat weld. dome of weld should be equal in height to one thickness of the steel being welded. takes a bit of practice to get the settings on the welder right. Don.

[Wayne 962]

MORE POWER - turn that amp up to 11!

-Wayne

[rennch]

Hey guys, thanks for the help. I enlarged the holes and turned the power up to ungodly proportions.

Check my link in the footer of the project car for the results.

Oh, and Wayne...did you get the shirts??