I am a relatively new welder and I am making a furnace rack for brazing radiators out of 2" square tubing and I am having a problem with heat distortion in the finished product. The rack is 72" x 65.5" with 4 solid pieces making up the outside and 3 solid stringers going the 72" way and 12 cut pieces going the 65.5" way (4 pieces making one string) creating a square grid effect (roughly
16.5" x 16" squares).All of the joints have been sealed with weld with 1" holes being drilled on the bottom side of the tubing for relief.The rack layed flat before it went into the furnace but after 10 minutes in gave me a "cookie pan" effect by sitting on 2 opposite corners and rocking (by the way the furnace is 650 degrees farenheight and the racks go in and out all day on 10 minute cycles cooling down for 10 minutes between cycles.There are 2 racks).
First I need to know how to fix this and maybe some design ideas for the future Thanks
-Buck