welding question

I have a millermatic 180 auto set, now i know how to set it using the same size metal, axample weld 1/4" to 1/4" plate. But heres what i need to know, if i weld, lets say some thin wall metal to 1/4 inch, i measure the thickness of both, do i want to set the welder to weld 1/4" or do i set it to weld the thin wall? I hope this makes sinse. Thanks.

 

I'm not sure if this is correct, but I would use the hotter setting and "play off" the thicker piece burning the thinner piece into it.

 

yup.

set at the higher steel thickness, and roll your weld up into the thin base metal. this is how i have done it... any pro's wanna chime in?

 

Technique compensates for the difference in thickness.

1/8" to 1/4" isn't too much trouble.
20 ga to 1/4" is VERY difficult.

 

Just keep the wire feeing into the thicker stuff, but make sure you still melt the edge of the thinner wall.

Another technique is to pre heat the thicker material, and run a lower voltage to compensate for the preheated piece.

lastly, a 2 pass technique can be used. do a very small thin pass, then go over it with a hotter cover pass. The extra material from the first weld will absorb some of the heat, avoiding burn through.

 

So say you were going to try and tac some thin sheet metal to thick steel, it aint gonna work?

 

Pro chiming in.............The throat of your weld should be the thickness of T1 (thicker metal) so set for 1/4 try to keep the face of the weld to the thicker side with out cold lapping the weld. (going off seam) The face of your weld should be at least as wide as your thicker metal also. Didn't your welder come with a manual?

 

tacking is easy, you can tack way hotter than you weld because you're only there for a few seconds.

i weld Aluminum all day, usually around 27 Volts, but i tack at 35.

 

Like the gentlemen before me said...

For a MIG, set the welder voltage and wire speed for 1/4". Start the puddle on the 1/4" material and drag into the thinner material in a overlapping circle pattern. Drag the puddle toward you, don't push it away. Spend just a fraction more time when you drag the puddle over the 1/4" material than you do on the thinner material. This will ensure you get adequate penetration on both materials.

 

Yep, came with manual and dvd, so far as i can see it says take the little tool that comes with it and measure the thickness of the metal, set the wire size and thickness and go. It dont tell me what if there is two differant sizes. Thanks.