Helping Son With Revision For Body Shop Repair

[Karamia]

Wondered if anyone can help.
What is advantage of using belt sander over an angle grinder with hard disc?
Is it because belt sander can get into all nooks and crannies better?
What is the cause of angular distortion in butt weld when welding?
Is it to do with speed of line ofcweld too slow or to do with the parent metal exceeding yield strength?
Any help gratefully received. Thanks

[Atheist]

Karamia; your son should have learned all that, not you! Oh dear, children! You do your best, but eventually they have to learn to stand on their own two feet. Good luck. I can't give you any technical advice; sorry.

[tonyav]

Regarding the welding, answer is to slow ( allows heat to build up to much and distort the metal. should really stitch weld it joining up the welds gradually ). Belt sander is much better on flat panels ( many flat panels on cars, doors etc ).