mig weld not sticking

[saintjohnbarleycorn]

I have been using the same setting , gas , technique as far as I can tell. I am welding mild steel to mild steel. about 3/8" thick flat plate. I not had any trouble with the welds.
Now on this plate it makes a bead but does not penetrate the flat plate I am welding on to. I have ground the surface , and it is smooth and shiny. Could the grinding disc I used have loaded the surface with aluminum or stainless or something else, or am I just missing something here? It is two flat 3/8" plates , one on top of he other and I am welding he 90 degree angle where they meet. thanks for any help on this.

[macbruce]

Turn your current up or your wire speed down......disc residue shouldn't make much difference..........

[saintjohnbarleycorn]

thanks

[John McPherson]

How big is your welder? Wire size? How many passes are you trying to do this in? Since you are not calling this a 1F lap weld, I can guess you have no formal training.

To do this in one pass, I would recommend a 350 amp welder and .045" wire. Preheat to 300+F would not hurt, either. Spray arc would be better than short arc.

To do this with a little 115V and .023" wire, well, that is going to take some doing. Grind clean, preheat to 500F, 3-5 passes. Weld a little, wait 10 minutes for machine to cool, repeat. Flux core would be better than solid wire for this.

In any case, skip weld to avoid distortion. That is to say, weld opposite corners and skip around, rather than going around in a circle.

[double_edge2]

It's not a polarity issue is it?

[Jocko 58]

When not sure more amps burn it in it's all fine tuning

[clinton]

What direction are you welding? Are you pushing the puddle or pulling? I prefer to push when I run hard wire (the gun is pointed in the direction of weld) this allows the arc to stay out in front of the puddle and you tend to get better penetration. Motion can help also use a side to side motion keep the arc out in front. Also if you can position the weld put it in the vertical position and you should get good penetration, going up with the weld

[Nakedanvil - Grant Sarver]

You can often do heavier welds with a small machine by going "vertical-up". Doesn't need to be plumb, just maybe 45° works good and do it in one pass..

[Alphonse]

Thats the ticket, Grant has got it, turn your welder up as hot as you can...max voltage and wirespeed and run uphill 30-45 degrees depending on what you can handle uphill. Keep gun square with the work. If that don't get it, the plate is too thick for your welder to properly weld it. IN ORDER TO WELD YOU MUST MELT and that takes Arc heat! 115v wire feed welders have a max of about 1/4"-5/16" welded this way. Any 240 volt wire feed welder should weld it uphill, if not flat, for sure.

[clinton]

One note that I would like to add is that you say that you are using the same settings- voltage can vary from the supplier of your electricity and this can and will make your welder perform different throughout the day.

[macbruce]

How bout letting us know what your welder is, that would help.......