Filler plate/patch panel Q's

I welded my fuel door in an now there is a fine crack showing thru the body work where the bottom edge is. The way I done it was steped the main body an spot welded the panel into it, the only thing is I didn't fully weld the panel since my welder don't burn cool enough. I'm curious as to how some of you have filled in your fuel doors, as in if it was welded in or glued/epoxied? An how did you seal/keep the elements off the back?

By just welding spots you have left areas that can still flex. This will cause cracking, it doesnt matter where it is at on the truck. The best way to do it if you can, is to weld it completely and then I always use a skim coat of fiberglass reinforced filler. I have shaved many handles, taillights, gaps, seams, patch panels, and have always had great results.......If you cant weld all the way around at least use the glass filler to try and get some extra strength. All fillers will crack if given the chance so try to do everything you can to make it as strong as you can.

I forgot to mention that there are some great panel bonding adhesives out there now that you could use....Just be sure its where you want it because once this crap dries you wont get it off...lol Check at your local body shop supply or you may even try an auto parts store that sells shop supplies.

You definitely need to weld it in solid or it will keep cracking. Just keeping tacking around it until its fully welded and take your time to let it cool in between tacks to keep the panel from warping.

The thing about welding the panel in solid is it warps the hell out of the main piece then it takes forever to do the bodywork. I had done my first shaved tailgate by tacking the plate into the opening, taking my time an I still fubared the gate. It got to hot or my welder won't go low enough an it pulled the body line out of the tailgate for about a foot an a half above the patch. I was also using a fan to try an keep the panel cool inbetween tacks. (My welder is a fluxcore BTW) The one that's on my truck now I used some steel weld epoxy from autozone and it turned out so much better. I kick myself in the a$$ for not doing the fuel door the same way now.

Not to thread jack here but i was gonna start a new thread asking about filler panels/patch but i decided this would be more convenient and on the same subject just different questions. Anyway I was just about to start shaving my doors and what not and this being my first time I would like to gain some knowledge before taking a run at it.

First Question: Is there any tips or tricks to shaving?
Second Question: I have a wire feed welder and I was wondering if this would work without warping?

I think that is all, thanks to anyone who helps.

I have a miller 180 with autoset, I can weld down to 24g with it, I use a few other trix too, adding clamping more steel to the area works for spot repairs, I use filler rod to absorb heat, and fill too.
Mostly its a patience thing lol, I have used several differenrt welders and it comes down to patience and technique torch angle etc.
check this page I did a little tech on a while ago

I cut a piece out of an old tailgate and made a patch panel for the gas door. I gotta lincoln 135 with argon hook up. Like MMdan said patience is key when welding sheet metal. The more time you take welding (letting it cool) the less mud work you'll have to do. I bought the wrong bed for my truck and welded the bed sides onto my bed and with like i'd say 5-6 hours it was done. Sure i had some mud work to do but for the most part since i took my time I had no waves to speak of. I really not found of flux core but I've seen it done. I've also seen great results with gas welding. You can control your heat a bit more with a gas torch rather than an electric welder. Plus its good practice for tig atleast i believe so. A gas weld is a softer weld so it takes vibrations better rather than an electric mig. just a few things i've picked up along the years. best thing to do is grab some scrap and practice on that untill you get comfortable with what your doing,nothing like messing up your bedside that you looked for 6 months to find. With practice comes experience comes great results