Welding woes

Now as I am sure is pretty obvious, I am pretty new to the welding and fabricating business. How much of a necessity is it to weld along the top perimeter the plating? (I have over 100 plug welds) I am really having issues. I have cleaned it multiple times with a wire wheel I just can't get a good bead to lay down. I can't get a puddle started without burning through the thin sheet metal. The area that is there is so small and tight to the top that I when I try to focus the puddle on the plate I can't get the puddle to move fast enough to penetrate the sheet metal. I am drawing a blank. Here is a pic of what's going on.

I hate welding to sheet/thin gauge metal, so I understand where you are coming from. MIG welding doesn't allow you to concentrate the direct the heat like TIG welding would. I would try using a whipping C motion, begin the puddle on the thicker metal then whip down to the sheet and quickly back up to the thick metal, pause, then back to the thin. Other wise you may just have to stitch weld this thing in an inch or so at a time.

"I can't get a puddle started without burning through the thin sheet metal." Try starting the bead on the thicker material, then just flashing or as miteclgst suggests whipping it over to the thinner material. Don't allow the arc to linger over the thinner material too long.

I've got to ask though, 100 rosette welds? Each side or both sides? That sounds like an awful lot to me. I'm wondering how many of those you burned thru the sheet metal and just don't know it because you filled in the rosette. Also regarding the top seam, stitch welding is what you want, you don't need/want to weld that entire seam.

Good Luck!

You can try using less power on the welder and stitch weld the upper seam. You should then seal it to prevent moisture from staying in the voids.

Full length, vertical welds on the uniframe is the WRONG place to be practicing your welds! Many experienced welders and XJ builders think vertical welds are a bad idea on the unibody, but when you're burning through and overheating the metal, you could really be doing some serious damage. IMO (take that with a grain of salt), your rosette welds are plenty... hopefully you did them right.
Billy

Those vertical welds are on the sides of a fish plate that covers another full length weld. That is there to add extra strength. This isn't all practice. I was just having issues in that one area because I had the pieces of plate cut so tight against the top of the wheel well that I couldn't properly direct the heat. However you have to start fabricating somewhere I figure a $250 mj is a good place to start.eace:

Try to pulse mig it. Basically a series of over-lapping tac welds that form a bead.

I just make my frame plating a good inch or so under the horizontal obstruction, so I have plenty of room to stick the welder in there and wiggle it around. A little planning and mocking things up makes things much easier.

HOLY rosette over-kill!

I prefer to pulse my mig (Miller 175) when doing the thick/thin thing, starting on the thick material and pushing the bead over to the thinner material. I set my heat and wire speed for the thicker.....then back the heat off a little bit if I get some burn-thru. Makes for a strong weld......pretty too.

I've plated my uni-rails from front tip to rear spring perch (not as many rosettes as yours though) and rarely burned thru the unirail. I used a flapwheel to get all the zinc plating (galvanized rust preventative) off the rails where I needed to weld, which is under the paint.

a big thing that also makes a difference. Sometime a wire wheel does not do a great job. I use a sand paper disc or flap wheel. Does a much better job.