Worse yet it is a weldment of *cast* aluminum pieces. Any tips or caveats?
Envision a large rectangular (single bowl) kitchen sink made of 3/8" thick cast aluminum. Only each end a separate casting and TIG welded together. Quite successfully other than the use of a stupid looking backer bar. Since removed as this is a bat house mold not a sink...
Was attempting to build up a pad on the out side so I could machine a shallow grove on the inside centered on the original weld. Far less familiar with aluminum MIG than TIG. Had a steel backer plate during welding that was inadequately clamped. The crack which alerted me to stop should be trivial to fix once I get as much of the warp as possible out.
Have modified the backer plate so I can clamp it much tighter. And will have one day only access to much better equipped shop than I have at home. Oxy acetylene with a rose bud, TIG, infrared thermometer, etc... Probably this Thursday though it may slip to next week if I don't get all my ducks in a row first.