I am setting up a motorized rotary positioner for semi-automatic welding of driveshafts , the tubing is A-513 HREW and the tubing ends are malleble cast steel . We use wall thicknesses of .134 and .180 , the joint is prepped by machining a 30 deg. bevel on both the tube and ends , the ends are pressed into the tube approx. 1 " , I prefer to leave at least .090 gap between the bevels . I am using a Miller 250 Mig with .035 hard wire
E-70s and C-25 shielding gas . Would it be better to use a dual shield wire in .035 ? I desire a finished weld with no undercut and 100% pentration, I need your ideas !