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Spot weld fine-tuning

R

RudyO

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Using a Lincoln SP-125 Plus w/ a 75/25 mix.
Practicing my spot welds before I do some patches and I played around with a range of settings. E-3 seems to get me in the best spot.

Is there something else I can do to improve the weld? On the 2nd pic, I spent more time on one weld before going to the next one, but I had blow through. Should I just look for the middle ground between the two?
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Not an expert by any means: What gauge metal? 18-22? Seems like the spot welds are quite large and would require a lot of grinding to finish off patch. Can't believe the panel on the side of your welder would say setting E for sheet metal. IIRC, when I was playing around with some sheet last year I thought I was around Settings B-4.5 or so. Think you need Rene or Rob to chime in here.
 
18 gauge. Cover calls for E-4, and I tried D-3, but the penetration wasn't as good. I agree, the welds do look too big. Definitely gonna be a lil clean up at that setting. All the welds I did had about that much build up.
 
Don't use a grinding wheel to smooth them, get one of those sanding disc to smooth them down. As long as you don't burn through and you get good penetration it's no big deal.

I had to do a repair on my 87. The door latch bolt on the body had busted loose so I just replace that part. Cut out a bout 5x5 inch square and just fixed the back part.
 
Figured I'd knock em down with a die grinder, then some sanding discs. Got a few packs of the two inch (?) ones.
 
I'm talking about a 4 inch sanding disc that would on a 4 inch grinder. It makes fast work of them and gets the metal ready for paint.

I wish I would have taken photos of the repair but at the time I don't think I even knew about this site.
 
Tried B-4.5 this morning. Definitely way too cold for this machine. Would a sharper angle help with the penetration? Doing roughly 20 degrees right now.
 
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Using gas lowers the welding penetration compared to flux core wire. I'd just try turning down the wire speed and use the settings in the first pic. If you're stitch welding sheet, just hit it long enough to bridge the two sides and no more.
 
What size wire is this with? I would try tuning down the wire feed a little or tune up the votage a little. It will put less material there and add a little heat you will just have to move a little faster. Or go with what you have and you will just have a little more grinding to do.
 
I'd go with .023 and try a slightly colder setting. To minimize burn through try starting the next 'tack' halfway on top of the previous one...gun angle pointing at the previous tack. Give it a second or two to cool between tacks too. I'm assuming you have an auto darkening helmet?

X2 on the 4" or even 5" sanding discs on a grinder for clean up later.

Where you have two pieces end put a tack right on each end to keep from burning through at the end when you do all the stitching.

Rene
 
I've always like burning a little hotter on thin stuff... welds lay alot flatter. You just need to really watch how hot the metal is getting and only pull the trigger for a very short time.

Got to the point where I could weld 12 gauge with .045 dual shield and it looked good.
 
I only suggested he try smaller/colder because he is already getting over 100% penetration from one side. You're right that hotter is usually better even on thin stuff. It takes a bit more skill/practice though.

Rene
 
:waytogo:

Looking at the welds again you'll find it alot easier if you make SURE you put each tach half way over each other everytime like rene has said. If you don't, you wind up with inconsistent thickness which can be a b*tch.


Also how long are you waiting between tacks?
 
Playing around with it in between rain storms today. Got one patch welded in (the toughest one). On this one, I get to work through about four curves and a brace. Still got a few pin holes to fill, but it appears solid. Definitely need to get more overlap though. Oh, and I'm using compressed air after about the fifth weld.
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Had to do this one in three sections. Couldn't get all the slight variances in the curves in just one. That corner in the lower middle of the pic is the worst part. It's a lil thinner there because of the stamping, so I tried to build it up a lil from the back side. That's the corner where three curves meet.

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Thx- not bad for my 1st ever sheet metal patch. Even had fun doing it! Only did this one first because it's the hardest to get to. The other two are almost flat and easily accessable.

Update- Got the last two patches in tonight. On the third patch, I got an epiphamy (?) and caught on to the technique. My goof was trying to spread the puddle a little. I consentrated on overlapping the tacks while filling a slight gap and followed it straight down, with just a bit of spark on the overlap. Just as the cherry red glowed out, I moved down a lil and pulled the trigger for split second. This produced total penetration and a very thin bead of about 3/16", while lying much flatter.

The advice was much appreciated and helpful!
 
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Good to see you were able to make it work the way you wanted it to. Sheet metal repair is some of the hardest welding to do (nicely) and there is a definite technique to it.

Rene
 
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