Welding a Gap

[Hellbringer]

hey i am doing some autobody work and i need to weld a 3/16th in gap. i have a mig welder but when welding i cant get it to weld to both sides. is there a trick to this??? thanks everyone Mike

[sanddrag]

At least to me, MIG seems like the best for filling gaps so you're already on the right start. 3/16 might be a bit wide but you should be able to do it. Generally, I'd try to keep the current a bit low and the wire feed speed a bit high.

Is this a flat, horizontal, vertical, or overhead weld?

When filling gaps, I prefer to go in an oscillating motion back and forth across the gap to get it to build up on both sides and bridge the gap. Some may use a circular method.

If you can get something (another piece of sheet metal) behind the gap that will help a lot to keep from burning and/or dripping through.

[Hellbringer]

that kinda makes some sence and it sounds simple..... i think another problem i am having is that i have a auto darkening helmet and i think i have it set to high so when welding all i can see is the arc. i cant see the outline of the metal or anything. what shade do you guys use when welding.

thanks mike.

[sanddrag]

I use a shade 10 with a gold/amber/organge filter for everything I do (from 40 amps on a .024 wire MIG to 125 amps on a stick). I find it easier to see than a green filter. Also, make sure your mig gun is pointed in a direction such that the gas shroud isn't blocking your view of the tip of the wire. You should be able to clearly see the tip of the wire and the weld pool.

Do you have any pictures of what you've tried to weld. Maybe we could offer some tips after seeing some pics.

[Hellbringer]

i will post some pics tomarrow thanks again guys

[lwill]

You can also try backing it with a piece of copper, the weld will not stick to it and it will draw away some of the heat so the original metal doesn't go "poof" instantly. Also use small short spots (1-2 second bursts) spread apart ==o====o====o=== then fill in between in stages ==o==o==o==o== ==ooo==ooo==ooo== =oooo=oooo=oooo ooooooooo get the idea? Let each pass cool well to prevent warping. As far as the helmet and seeing the arc, this works for me - try not focusing "directly" at the arc itself but 1/8" to 1/4" along the gap to guide you. This way you should be able to see the edge of the puddle and how big it is getting which is the important thing anyway, not the arc. Even with a dark glass your eyes adjust to the brightest spot and you will have a hard time seeing anything even slightly darker. Sort of like watching the white line on the side of the road at night when a car is heading at you instead of stairing at their head lights and getting blinded.

[Zumba]

Originally Posted by Hellbringer i cant see the outline of the metal or anything. what shade do you guys use when welding.

Mine's set at 9, the lightest setting. I wear slightly tinted safety glasses inside, which adds to the darkening.

[Geof]

A technique I have used is to run a fast bead a few times down each side of the gap. It doesn't have to be nice and smooth and continuous all you want to do is build up a bit of metal thickness to act as a heat sink. Let things cool for a while and then start stitching across in a semicircular motion.

[DennisCNC]

Do you have a CO2 MIG or flux core? Is it a 110V or 220V?

[Hellbringer]

right now i am running flux cored and it is 110v but it able to run mig

[mxtras]

I second the copper back up suggestion from post #6 - he gives a lot of good advise in that post! You can focus the weld directly to the copper and let it flow out to the metal (in a really quick kinda way) - the weld will not stick to the copper. He pretty much layed it out in post #6!

Scott

[Hellbringer]

thanks guys i will try the copper idea

Mike