I have been practicing before starting on my rear quarters. I am able to put a nice weld down on a piece of metal but when i try and weld a joint between 2 I seem to be either burning thru or making a mess. i am using 024 wire. Should I be using 035 when welding a joint? If I am able to join the 2 pieces perfectly tight I can weld them but if there is a gap, well lets just say the gap gets bigger. Any help appreciated. By the way I am practicing on 20 guage

Don't try to lay one continuous bead on sheetmetal. When welding sheetmetal, you want to do so by tying a series of spot welds together to form a continuous weld. This means hitting the trigger, forming a puddle while making a small tight circle, and letting off the trigger. You make a spot weld as opposed to a bead or string. This should take no more than a second. You let it cool for two or three seconds and weld another spot right next to it and tie the two together. Do this four or five times in one area and then move to another spot on the panel several inches away and repeat the process. You continue this until you have tied all the spot welds together to form your continuous weld. If you don't move around, you'll warp the panel.

First you need to make sure that the welder is set up properly, you should hear a constat BZZZZZ. If you dont hear that constat sound you need to readjust the settings. Also when doing each type of weld the welder takes different settings. You might have to slighty adjust the heat and wire speed to help adviod burnthrough.

Also try the 2 different types of holding the gun as you weld. There is the push and pull methods, both with different charactertics. Its hard to explain but the push method is welding into the weld pool, were the pull method you are welding away from the pool. Alright say you are welding right to left, now the pull method the gun would be pointed at the outside on the left hand side of the weld pool as you move right to left.

The pull method to me seems to create alittle less heat and is easier to preform the buttweld. Also keep with the .023 wire, that .030 or 35 wire takes so much more heat to melt into the weld pool thus creating more wrapage. Leave the 30 and 35 wire for the heavy metal like frames.

Always leave a gap when butt welding. When welding metal expands and if you dont have a gap the metal has no where to go so in turn it forces your sheetmetal to get bulges in it because the butted up metal is expanding. As for the gap spacing I always use the width of the wire am using. I use .023 wire so my gap should be around the same.

Also what type of gas are you using? If you are using CO2 you will get deep penetration but you get of more unstable arc and splatter. A mix of 75 argon and 25 CO2 are the perfect mix for thin sheetmetal. You wont get as deep of penetraion but you get a much stabe weld arc, and when you get a stable arc you create less heat tus reducing wrapage and burnthrough.

It also sounds like you are not tacking welding the pieces together first, it sounds like you are starting on one end, then welding straight thro to the other end. When you do this you pull the pieces apart creating your increased gap. A tack weld is just a very small weld used to hold the panels in place, its roughly the size of nail head. Place a tack weld every 1 to 2 inches. Once you got your tacks in place you can start welding that seem shut. But dont just weld straight through, only weld small portions then move to another spot. Weld a bead around a 1/2 to 1 inch long then move down the seem and make a new bead. You continue to do this til you have the seem fully welded shut. Doing this puts less heat in an area allows the metal to cool down allowing for less wrapage and blowthrough...Eric

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i understand that Randy, but it seems when i try and spot weld at a joint in the 2 pieces with a small gap I always seem to blow thru. Thats why I was wondering If maybe I should be using 035 wire. I have adjusted wire speed and voltage down but not having too much sucess at this point. I will be at it again in the morning. On a solid piece I can lay a nice spot weld down. Oh well, more practice

Thanks

I was laying a constant beed down on a piece of metal and adjusting wire and voltage to the point where I got that buzz and produced a nice bead, just to get a feel for things. Thats when I then tried the spot weld on a joint. I will continue practicing, just wanted to make sure about wire size and as for the gas, to be honest I have to check and see whet I have. When I bought the unit they filled the bottle and at the time I never really knew there were different gases to use

Thanks

Contact your local paint store,spend a 100.00 and get a holepunch-flange tool.This will help greatly for what your trying to accomplish.
Second of all this tool will punch holes that you weld thru to the other panel and also around the edge of the hole and will give you a body filler seam about 1 inch wide and 1/8 inch deep.
Continuous bead welding on panels that thin will warp your panels and create more of a nightmare than you asked for.Then you have to get a torch and heat shrink the metal(pain in the posterior end)
.023/024 wire is what you want to use and remember these 2 points about welding heatsetting=voltage.....wire speed increases amphereage

usually there is a chart on the inside of the door you lift up to replace the spool of wire, this will give you your power setting and wire speed.

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here's my tip. I just started welding a few months ago. This works for me.
Make sure you have the gap desribed by others of about the wire thickness. then touch your wire to one side of the metal and pull the trigger, and immediately move across to the other side. Do this in one quick motion, taking no more than one second. Basically a quick squeeze and you will find the molten metal has bridged the gap. This is a tack weld. Then do as described by others. Make many, many tacks, then if you have them about quarter inch apart, you can try and run a bead between them.

Horsepower TV did a segment on sheetmetal welding just this weekend. They demonstrated the technique very well. If there is any way to put that one segment on a server somewhere, it would be worth its weight in gold!

Another trick that helps is to lay a small piece of metal across the gap from the back side. It doesn't have to very wide. It just needs to keep the weld from blowing through. Some people like to use brass or copper to keep from blowing through, and some like to tack a narrow strip of sheetmetal along the back.

[This message has been edited by Randy Mosier (edited 01-26-2003).]

blumont, one other thing. Be sure to cut that blob of metal off the end of the wire each time you are about to lay down a new tack weld. It takes more heat to melt that big round piece of wire, which contributes to "blow thru".

You can also try clamping a block of brass to the back of the joint to help absorb a little of the heat.
A block about a half inch thick and about 2"x3" should do it.