I used a combination of cutoff wheel on the grinder and the cold chisel and lots of elbow grease. I was primarily focused on avoiding damage to the frame - but did end up with a few nicks here and there with the cutting wheel.
Wirewheel and flap disk on the frame, got it as good as I could, but not what I'd call pristine.
I then fabricated replacement straps with holes to plug weld.
I sprayed the mating faces with copper weld-through primer and bolted the straps in place.
I clamped the straps down and plug welded the holes. Those of you with any experience at all plug welding can likely already predict the issue I had - because my plug holes were too small, I had barely any penetration at all into the frame - one little tap with the hammer and they popped right off. Live and learn! I'll be redrilling the plug weld holes and starting over again.
I've plug welded in holes that small with success. Use .025" wire and a fair amount of power. I would be most concerned that you applied the rust prevention and that is likely interfering with your welds.
I suggested you leave the plug weld spots open to bare metal. Even weld through primer will affect the weld. We used it sparingly when we had to walk away from the metal and didn't want rust. Welding after the fact was possible but the weld pool was not good. Anything other than bare metal will affect the quality of your penetration.
Mock up a test piece to practice on with the copper paint and all and then play with the heat setting on the welder, it needs to be way high in that thick metal...
Mike B
Mike B
1953 M38A1 Brush Truck
1952 M38
1951 M100 Trailer
Mike_B wrote:Mock up a test piece to practice on with the copper paint and all and then play with the heat setting on the welder, it needs to be way high in that thick metal...
Mike B
I think this is what I'm going to do - I don't really care much about redoing work or screwing up the new straps I made, my primary worry is causing needless damage to the frame. Researching online, it seems the minimum plug weld hole size should be "thickness of the material + 5/16 then rounded up to the next 1/16th" and maximum size is 1/8" more than that - for 1/8 material, I believe this works out to: 1/8, i.e. 2/16 + 5/16 = 7/16 - so I'm going to use a 1/2" drill bit to expand the plug holes I have in the strap to redo them.
I did some more work this weekend. I cleaned up the straps, re-drilled the plug holes to 1/2" and redid the weld-through primer. I bolted the reinforcement straps on, clamped and scraped away the primer in the hole as well as I could and then welded them up.
Result:
This looks much better to me than the earlier one with the smaller holes.
I then dressed them with flap wheel and used seam sealer and then painted liberally.
