Ive got a cpl of patches to weld on my 7, the biggest one will be about 4"high x long14" on a rocker.
Ive welded off and on all my life but never anything this thin (I used to consider 1/8" thin) I know I'll have to "connect the dots" as opposed to laying a bead, my questions are: How tight to dry fit my patch? flush? or 1/16" all the way around? or more on the long sides? And secondly the sequence of my tacks? should i tack all the corners? and jump around like torquing a head?
or just start on one end and tack top then bottom working left to right?
Im trying to avoid it looking like a motocross course when Im done.I just have no idea how this thin metal will grow or draw. any advice will help. thanx..OCG
P.S. while Ive got a Lincoln 220 stick that Im pretty good with Im planning on using my Lincoln wire-feed/flux core to do this even though Its new to me and I haven't used it much.
If I was you I would practice mig a little on a scrap piece! Mig is super easy to use and learn. But make sure that you use gas when doing this weld. It could come out sloppy if you don't! And flux-core might be too much for this thin of sheet metal. Usually I use regular .030 wire for sheet metal work. Maybe .035 sometimes.
As far as welding technique goes, I'd start of by doing all of the corners then jumping around like you're torquing bolts, just like you said.
GOOD CLEAN METAL, make sure you cut it back far enough to get to good metal, uwelding rust is tough. No gap as Alex said and I agree practice even if it's just with what you got. Corners, bounce around, compressed air to cool thins down at times, copper backing to prevent blow through. Depending on where it is I like to lap weld for ease and convenience. When it comes to MY sheetmetal welding a grinder and seam sealer or spot putty are my best friends.
Careful your character's showing
A copper backing strip will make filling the gap easier and help draw the heat out of the metal. When I do thin metal on bodies, I try to put a backing piece behind the joint. It won't look pretty on the back side, but you will not be chasing burn holes.
Beat it to fit, paint it to match!
I like .025 wire for thin metal, and you will obviously use less heat. I use solid wire. Keep your gun close to the surface and WATCH the weld. You will SEE when it is good. It will take just a second, and you will get into a rhythym. I think you would benefit tacking all four sides. Use a magnet to hold the patch in place. Weldable primer should probably be used. I like a tiny gap, and a buddy of mine likes to make a flange on the edges. I have never done that, but he swears by it! The copper backing is a great idea. You can make one by flattening out a piece of 1" copper tubing. An auto helmet would be a great advantage here, and you will need to shrink the metal when you're done welding/grinding.
__________________ Kerrdog Go Fish! <*////><
But the right word at the right time... "Hey, give me a little hug!" That's the difference between lightning and a harmless lightning bug!
Flanges wont create a problem if osphosed and sealed properly when done. Anything unprotected will rust in time. Done properly it is stonger. I personally weld 99% of the outer panels with a but weld and flange most floor work, OR go to the factory seams whenever possible. Getting better at it everyday.
Careful your character's showing
Tight fitup will help prevent burning away edges. I usually tack a few places to hold the patch in place. Then, jump along about every 2" or so.. going around the perimeter of the patch to keep heat down. I also keep a bucket of water with a rag right next to me. I'll do a few tacks, then quench with the wet rag to keep the metal cool. You don't have to get sheetmetal too hot before it expands enough to cause warpage. Tack, tack, quench....
While thinner wire (and gas) make it easier, if you're careful, you can do a good job with .030" or even .035".
'80 CJ5 w/AMC360, T176, D44 w/Detroit 4.56, RE 4" YJ lift and 35s..
I never thought about round corners, makes sense, while I wish I had a mig mines only a flux-core wire feed, I think if I take my time I can manage OK, Ive got a lot of scrap laying around I can use to get dialed in. thanks to all for the advice...OCG