Frame patch thickness?

Well, I'm going to purchase my FCAW MIG welder today on the way home. I figured with the amount of repairs I need to do to both the body and frame, I might as well learn. I need to start by patching the holes in my frame and welding on new body mounts. What thickness steel does everyone recommend for patches? What is the OEM frame thickness? Also, I'm new to the welding seen and I have a few questions: 1) will I be able to use the FCAW MIG welder to attached my sheetmetal repair panels (18ga) to the existing floor or is the metal too thin? 2) which rods does everyone recommend for these types of repair? Thanks.

 

Ummm, first MIG (FCAW) does not use "rods". it's wire feed. Use .023 for the thin stuff, keep your heat down, and alternate welding around the patch or you'll just burn a hole in it. You will have MUCH better results using unimix gas rather than flux-core wire, too. Well worth the cost of tanks and regulator.

I'd gather up some scrap metal, from 18ga up to 1/4", and practice, practice, practice before you start actually trying to fix anything. You'll learn a lot. You'll be hours ahead if you can find someone to show to the basics.

If there is any major rust on the panel, you need to cut all the way back to solid metal, as the thinner rust pits will burn thru very easily.

For patches, I like using a slightly heavier gauge than the base metal. This makes it easier to manage the heat, as you can direct some of the heat into the slightly thicker patch metal. You can use a chunk of solid copper to back the weld to help with the burn-through on really thin stuff (the weld won't stick to the copper).

I cut patches carefully to fit exactly in the cut-out area, and butt-weld. Overlapping panels like too many people do will trap water and rust thru again. Welding magnets work good to hold the patch in place and flush until you get it tacked in place.

Good Luck!

 

BTW, I used 3/16 to patch my frame. Taper the ends.

 

I told you I new to this welding thing! Thanks for the info. Would I be better off (and less likely to melt a hole) brazing the new sheetmetal in and leave the MIG welding for the frame patches? Everything I've read says brazing with nickel-silver rods is as strong as MIG welding and your less likely to mess things up since the temperature is lower. Help me Obi-wan....your my only hope........