Welding problem/question?

[73Charger]

I was having great difficulty trying to weld my new floor pans in and I wonder if it is just my poor skill or I need a better welder.
Basically the floor is thin, rusty, and I've cut out filler where I saw it too. When I tried to weld thin metal or pan back to the sides of what floor was left, my weld would always burn right through leaving me with a whole which would take even longer to try to fill.
My welder is a cheapo $80 flux only welder with two amp settings and cont wire feed setting. I've been trying the low current and slow feed to try to not burn through but with no luck.  Since its just the floor, I don't care about a clean weld, just want it solid.
Can I do it with this welder or do I need a mig w/ gas to do this thin metal? 

[Silver R/T]

You definitely need better welder and lost more practice before you attemp to do bodywork on your own Charger. Odds are that metal you're trying to weld to is not there anymore its just rust that looks like metal. YOu need to clean off area where its going to mate with new floor pan and then spray weld through primer on. Did you flange it? YOu need to do so when putting in new floor pans

[Todd Wilson]

A MIG Welder with the gas would be the better choice here.  You might try and turn the wire speed up some to help shove new metal into the weld. You also are not gonna want or be able to fire up an arc and go non stop. You will have to zap small stitches all around a circle until its all welded in. You dont want things to heat up and warp on you.  You also might be moving to slow causing a burn thru. It could also be weak metal you are trying to weld too.  If you have a hole that needs filled in put copper on the back side and fill in. The copper takes the heat away and the weld wont stick to it but the copper will act like a mold. I have  used copper bars, pennys and a piece of a copper water pipe to back up a pin hole or something that needs filled in.

Also make sure your polarity is set right on the welder per your instruction manual. My new Hobart was not set out of the box for sheet metal. After making that change it was a noticable difference in the way it welded.
This setting may be a switch and it make require you to swap the ground and gun leads around inside the unit. Theres a chance your welder doesnt have this option. Read your book here or look inside the cover as sometimes theres instructions there.


With all this being said it still could be your skill level that is the problem. I took welding back in school and was pretty good at it but going from 1/4 inch steel plate with a Lincoln Stick welder to sheet metal and a MIG is a different ballgame.



Todd

[RogerDodger]

Make sure you get back to good solid metal. Even an experienced welder will blow a hole through thin rusty metal. Try adjusting the wire speed. Floor pans are a good place to practice. And like Todd said weld small sections less than an inch at a time. Move around to different places and spread out the heat so you don't get warpage.

[70charger_boy]

I have the same flux core welder you have.  What works for me is set the heat to MIN and the wire feed at 3 or 3 1/2.  You will have less burn through at the fast wire feed.  Also, have a wet rag with you to place on the hot spots never start the weld at the beginning or the end.  You wanna start in the middle then make tac welds every 10 inches

[73Charger]

Thanks for the great ideas. I had attempted this last season, and I figured the floor was a good place to begin since nobody will see it    my cheapo welder does not have any plarity switch, just got it from harbor freight. it has worked on my old winter car, patio furniture, and tools fine. I will try again this year at 3 speed and low amp. I think I am using the standard .035"? wire too, but would a different type help?

My pan is bent down at the front and sides so that I can get a 90 degree weld and what I thought would be more strength than a flat butt weld. Is that the way to go?  I also had a hole in the rear pan that I tried to close up with a small piece of sheet metal but my tacks would warp the metal piece and cut through it.  I guess I need thicker metal. What thinkness should work for a floor pan mend?
I have two new pans for the front, but nothing for the rear, and have found the rear is rusty as well.
In case you haven't noticed yet, I'm on a low budget for now. I just want to drive it. Don't care too much how it looks. I've been driving it for years in rattle can paint until I find the money to paint it. Do I need to buzz off all the paint that still exists on the tunnel area before I weld too?

My first big project this year will be to get my shit ass brand new summit headers on without a leak.  I tried all sorts of things last year and they leaked like shit. The old one were fine but were rusty at bottom with holes. Now I'm going to try the best gaskets I can find - the aluminum seal for good ones to see if that does it. Once I get that right, I'll weld new pipes to get them to fit the custom exhaust that fit the old headers, then get it inspected, then get back to playing with the floor, but I thought I'd start getting info now.

[Mike DC]

       
Are you using .035 wire on floorpans?  If that's the case then start by dumping the .035 wire ASAP. 
Get some .023 wire (and the necessary .023 gun tips, of course) for thin sheetmetal. 

You can basically choose .023, .030, and .035 for the kind of steel you're messing with.  Thicker metal = bigger wire.  Use only the .023 for car body panel sheetmetal. The .035 is better for 1/8" or 1/4" plate steel fabrication work.  The wire size makes a HUGE difference in how it welds.  But thinner wire also demands that you give it more voltage than the same sheetmetal would require with the thicker wire, so compensate accordingly.

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It's just personal preference, but I find myself running the little .023 wire for almost anything thinner than 1/8" steel. 
I tend to err a little bit under the normal wire size recommendations and compensate by throwing more voltage at it.  (But it's a 220 volt welder which allows you to really put more heat into the little wire than a 110v welder can.  I'm rarely being forced to run thicker wire just to get decent heat/penetration, and that's usually the case with lower-powered MIGs.) 

Smaller wire size tends to result in more control over the weld puddle.  Just make sure you're always getting enough heat/penetration on the metal.

 

[73Charger]

I just took a look at the website that sells this type of welder, and I think it can only handle .030" or maybe .035 as well so I maybe wrong and I'm stuck with that if I can do it with this one. so the assumption is I'm working with a welder very similar to one of these http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44567
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=55167
It has some different markings, but has same controls.
So my first question was - is it possible to do it with this welder or do I need something better (not looking for show quality - just a solid floor)
So far I got differing opinions. I guess I will try with it again, but sand down any painted areas (the tunnel ) first.
I'm not sure what the weld through primer is? is that to make sure it does not rust while you work on it? where do you get that?

The question about flanging it I did not understand. Does that mean to bend the metal edges so they are 90 degrees like I have now? or is it some kind of treatment of the actual edge of the metal.

Since my whole floor in the front is basically gone, my only real good spot is the tunnel and most up front by the pedals.

How do I deal with crap for metal near the door side? Do I weld a piece onto the frame rail and then weld the pan onto that?
I could post a picture, but its real ugly.  and I cant' find them right now.

[squeakfinder]

Seems like with flux core wire .030 is the smallest you can get. The .023 solid wire with shielding gas would as stated would be better for such a thin gauge metal.

A flange, is putting a lip on the edge of the metal you are welding on so the two pieces overlap. Eastwood sells a tool to do this but I'm not sure how good they are. If you bought replacement floor pans, I would think they would have this lip that I'm talking about. If not, I would simply overlap the new piece an inch or two onto the existing floor, your going to be covering up with carpet or a floor mat anyway.

The paint mentioned has a high zinc content, never used it myself, but the idea is to spray it where the two pieces meet to help prevent rust.
The zinc helps the conductivity of the two metels. You can weld threw rust and paint with a stick (arc) welder but with a wire feed you have to have a good clean ground.

You might get away with doing this with your welder if you slowly spot weld your way around, as soon you strike an arc,let go of the trigger after about a second. Maybe this will cut the heat down enough to keep from burning threw.

Good Luck Larry.