Lugs: an egghead's observation
background: Invested casted lugs were considered to be the touch of class. Massed produced frames often had lugs that were stamped from sheet & welded. This was often offered as the distinction between great and OK.
Now, not that I am any expert but basic metalurgy is very clear that a casted part has a granular structure that is without direction, sort of like partical board. meanwhile a sheet has distinct directional grain structure, like a board of wood. therefore shouldn't a lug that is formed from a sheet is stronger that one that is casted????
OK, there are other factors involved. An investment casted lug can be made to very exacting tolerances, therefore the fit to the tubes being joined can be very consistant and therefore a lower temp higher silver brazing material can be used. A stamped part is at the mercy of the dies used and the amount of bend yu can put in the material, this and springback and other metal forming issues will result in a part that is at a looser tolerance and will therefore require a hotter more gap filling brazing material.
So how does it all stack up? which is better? casted or stamped or what????