Rather than use beads of weld,I think the best way of doing this is to get say a piece of 10mm square stock and cut 6 pieces the same size as the axle hexes.Thats when I go to my 12 inch grinder and and as dusty says bigger hammer to make it fit. Everyone has good ideas on this I may need to use one keepum coming.handy
then chamfer each one along its length.then position them around the axle(first grind flush the old weld,)with the chamfer towards the hub and weld them all in place...There would need to be a couple of thou shims under each piece before welding to give sliding clearance and try sliding after tacking before final welding.
An even better way if you have a lathe would be to recess the hub so all the pieces fitted inside which would keep it all concentric.
I have also found that on older worn hubs its not effective to just torque them..What happens is the end of the bolt wears down and a dip is also worn at its contact point on the hub which means the bolt is tightening on the spring coils and not where you need it ,on the hub itself...Although I have been fitting and welding for over 50 years I am rubbish at drawing otherwise I would post some pics of the plan
Dave