Quote Originally Posted by JAZZCNC View Post
Joe I've drilled holes just less than dia of M12 nuts so tight fit then knocked the nuts into holes just below surface with bolt in threads to protect then weld in place then grind welds flush.

Edit: That was for in middle of sections. At the ends were I could reach I just drilled M12 hole for bolt put nut on inside and welded from inside.
Little more involved than I was Intending but I guess m6 with only 3threads engaged is a bit measly when I think about it! Are those bolts in your photos earlier on this thread m12 then? They look smaller somehow.

On the x axis RHS presumably you don't weld bolts in place - what do you do there? Hope you don't mind giving away all the trade secrets!!

Cheers
Joe