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Discussion Starter #1
I am welding in floor pans in my 66 coupe with my Hobart 175 amp welder. There are 4 heat settings (1,2,3,4) and 10 speed settings (10,20,30,40,50,60,70,80,90,100). My floor pans are the cheap ones. When I set the heat to penetrate the uni body, it melts the floor pans, when I set it so it doesn't melt the floor pans, doesn't seem to penetrate. The floor pans seem to like a 2 heat setting and the unibody seems to like the 3 heat setting. I know I need to fine tune it, but any suggestions out there? faster speed with lower heat etc...
 

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I would start with the higher heat setting and focus the heat on the frame rail, just kind of 'bumping' the floor pan with the bead. A faster wire speed may help you maintain a workable puddle. The right combo of heat and wire will take some 'tuning' as you go.

Penitration is the key to strong welds.

Be sure to grind the frame rails to bare metal to make it easier on yourself.
 

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Discussion Starter #3
Thanks for the quick response.

I have ground the frame welds and get good penetration on the uni body, but it seems to discentegrates the floor pan I come in contact with it. Guess I will have to keep playing around with it....
 

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Getting the knack is somewhat frustrating.......especially with thin metals....

Here's my "barely could call myself experienced" suggestions;

1. as stated, run a higher wire speed....right now Im doing a lap weld job on fairly thin metals and my wire speed is about halfway up (though I am bridging too big a gap, LOL!!!)

2. I find doing a zigzag easier (side to side a little bit as you go).


3. KEEP THE NOZZLE VERY CLOSE TO THE WORK!!!!!!

4. USE ENOUGH LIGHTING SO YOU CAN SEE WHERE YOURE WELDING!!!


5. The "stitching" thing (do 1/2" of the seam in one area, then go to a distant area of the seam) helps to prevent burnthrough (the entire area will hold heat).

6. KNOW WHATS AROUND THE WELD AREA (IE FUEL LINES) AND ALWAYS HAVE A FIRE EXTINGUISHER HANDY!!!

7. The metals being joined need to be clean and bare for best results.


8. Welding thin metals with shielding gas is infinitely better than using flux core wire.
Best of luck!!
 

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Dident mention if you are useing flux core or solid wire with gas. The flux core will dig alittle deeper. But the solid wire with gas is a better choice for floor pans. The idea is to concentrate the puddle on the thicker part and push the puddle to the thinner.
 

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ive found on my lincoln a 3 setting with a high wire speed seems to work well. good look and remember you havent even got to the fun part :: yet. grinding all those welds.
 

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Use the higher heat setting. The lower setting will result in poor penetration and weak seams. You need to control heat by creating a puddle and then releasing the wire feed for a moment as the metal cools then continuing. The wire speed has an effect on heat also. Slow down the speed to run cooler. Tack the pan into place with tacks every few inches and then run a bead starting at the tack. The tack acts as a heat bridge to transfer heat into both sides. When you start to see the metal really starting to glow, release the trigger and let the metal cool until the glow dissapears, then continue as I mentioned above. If your welding vertically, run the bead downward instead of upward. You may trap some slag, but the heat control is much easier especially for a beginner. Downhill welding took me a while to get used to because I was always taught to weld upwards when I was a certified arc welder, but since your not getting your welds x-ray'd, do it downhill.
 

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You've gotten good advice...

How I'd handle it..

On scrap of similar dimensions (thickness difference), I start with 3 and 50 as a reference point and work from there.

Gas shielding, .023" wire ( I use .030" but have extremely fine control on my commercial machines)

Stitch weld, as was mentioned. This functionality is built into my machines.

Use of backing plate of 10 guage or thicker copper can help; experiment with smashed copper water tube to evaluate.

Cleanliness......did I say cleanliness? *G* Very important on thin materials. Sometimes they dip the sheet metal in something to mitigate corrosion and that needs to be removed or etched.

Remember the first thing I posted.....Scrap first, then weld the job.
 

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i'm by no means an expert welder, but i had the same problem welding my pans as you are having. my welder has 4 heat settings, but infinite wire speed settings. i got the best results by turning the heat down, and slowing the wire speed. this allowed me to concentrate the weld (thus getting sufficient pooling and penetration) without too much heat to blow through the thin sheetmetal.
 

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Discussion Starter #12
I spent some time today grinding.....I need some Arm covers as it is hard to do in short sleeves. Texas heat makes it tough to weld/grind outside with long sleves on.
 
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