What a delight

Spending hours cutting, measuring and stitch welding (still not done). What is my reward? Sheet metal buckling. Slight but buckling anyway. I'm used to replacing floors in first generation Broncos that have the metal rib stamping for support. For the Willys it is flat sheet metal prone to do what it did...arg...:(
I'm probably over complaining but I like my sheet metal straight, like my women.
Looking back, I probably didn't move around the perimeter enough with each weld.

When I do the other side I will spot weld a few areas on the newly installed supports under the floor and see if it helps. Then, proceed to stitch weld.

That should come out when you weld the floor to the hat channel that goes under it. They are definitely not perfect even when they were new.
it is a big flat piece of sheet metal. When you unbolt them from the frame they do "move around". The tubs find their own shape once they are firmly bolted to the frame.

That's why I prefer salvaging original floor boards. The original steel likes to retain its shape better, and less likely to warp. On the A1 project I used an original driver's side floor pan. The passenger side was a reproduction. I did get impatient and put too much heat in the inside corner of the tool box, and it pulled up a bunch. I later applied heat to the zone, and bashed it down into place with a 2X4" and a 2 lbs. hammer.

I always find butt welding a challenge. "But"...I run a narrow stripper of 1/2" wide underneath. It gives me something to weld to while tying both sheet metals together.
Nice work GM

I use a copper "spoon" for finished sections that can be seen and reached. This also helps to dissipate heat, and limit deformity when you stay too long in one spot. Copper pipe flattened out works well as well, especially in tight spaces.

Thanks for the tip GM and Mr. B . I just happen to have some 1/4" copper plate looking for a job.

mike