Welding Tips and Tricks

I had to build 11 of these stainless table tops. They're about 72 inches long and about 40 wide. The top piece is 18 304 trim pieces are 14 gauge. I have built about 30 of these before but my boss wanted to save some money and not re grain the top of the tables, so I can't get any build up on the top. I set them to corner to corner and just fused them. The problem is I am getting a little distortion on the 18 gauge top, which never used to happed because I didnt do them corner to corner before more like half a material. The corner to corner takes more heat to radius than previous fit up. The distortion isn't a big problem cause they get glued down to a wooden top hut still would like to avoid it if possible. I am close tacking the entire top, a tack every half inch, then welding 4 inch stitches back stepped, spacing them about a foot apart and using that pattern till everything is welded up. I am also air cooling every weld till it's cold before doing another weld. Anyone have have other ideas on something else I could do to avoid the distortion? I work in a production shop and only get a hour to build each table top. I would like to do smaller stiches but that takes a lot more time.

Using chill blocks clamped adjacent to the welds is the only their idea that comes to mind for me. 1/2x2” flat stock in 36” lengths should do nicely. Clamp one on underside and above. Also adds a backside argon dam for that fused weld. Reusable, lightweight, and slide around simply.

thanks for the idea! there is kinda a aluminum base I build them on but it doesn't fit super tight more for running the parts through the timesaver to re grain the top when we did that. mayb next time ill try and clamp down the top to that base. I usually use 2 large inspection squares to try and hold it flat.