>"Why must the lug edge face be at 90 degrees to the tube surface? Why must
>it's base (or root?) be a right angle? Is it wrong to like a touch of
>roundness to one's edges?"

well that's a tough one to answer without seeming
overly opinionated - but i'll try...

you're the one that mentioned "mini fillet...", so
i'm assuming that this thread is about keeping it to
a minimum or even removing it vis-a-vis* by wicking
the molten filler away using the trowel method (!).
perhaps i am misunderstanding all this. regardless,
since time immemorial the ideal has been "clean brazing"
and crisp shorelines. otherwise, why make any distinctions
between what "we" do and what industrial-made framemakers
do? (obviously, there's more to the distinctions that
"just" brazing skill levels).

as dave b. pointed out, if you're removing anything, it is
the "overfill", and imo the goal is to have a lug edge that
is sqaure and fully defined. if material is left on the tube
by the lug, the details will get murkier when a few coats of
paint are applied. is that acceptable? i think you get the

i realize that the learning curve prohibits newguy brazers
from getting it right early on, but to suggest that it's okay,
or even your own special aesthetic, to leave a "mini fillet"
at the end of a braze sequence seems counter-productive to
keeping the standards as high as possible.
*i like peppering my posts with zany french terms.