X3 on the puddle weld. Weld from the top. I recommend a weld every inch. I use a divider to make nice even spacing. Get the floors to where they are going to sit.. Now you need to make a seried of holes that match the frame rail flange. Pop a few self taping screws in to make the positon repeatable. On the frame rails, drill la 1/8th hole up from the bottom in the middle of the frame flange and up through the floor at both extremes of the frame rail. Now you can run a staight line between the holes to mark the position of the framerail flange and drill all the holes with the panle on the bench.
As Chris Roop mentioned on another post. there are a lot of dodgy puddle welds out there. Good thing we go overkill on the number of them. Clean the flanges until you can't stand it anymore. If I do another floor, I am getting a sand-blaster to clean the things!
Get the two pieces of steel tight before you weld. I address each spot weld individually to make sure ther is no gap. I use a floor jack ad some steel in the under-dash area to help push down. In the open areas, I use a helper on the end of a notched-out tube. Get below and see if a little tap won't bring the flange closer to the floor.
Buy a de-burr tool and remove the drill ridge that always results as you drill through a panel. This will help keep the panels tight.
Weld-thru pirmer is something that I used to advocate but now avoid. I just don't see where the crap is doing the weld any good. Does not work at all with a TIG welder.
Don't try and puddle weld with the 3/16" or whatever size HF punches with their neat flanger punch tool. The hole fills up before you get a chance to melt the lower panel. Looks good from the top but no penetration. Use those as a pilot hole and go 5/16". Turn the heat up. If you don't see molten steel from below, you are cold. If you are making holes, move faster. Bonus of welding hot is that you wont have much if anything to frind off the top. By the time you do the first 100, you will have the hang of it!
Pete
