Corky Scott wrote:

Even if the tube ends up having an eighth inch play or slightly more,
it doesn't matter. You will be putting enough filler material on the
weld that the fuselage won't care, and no one will be able to tell
that it wasn't precisely flush. Won't matter in terms of strength and
safety either.

Corky Scott


My experience has been that the tighter I get the fitup, the less warp I
get in the finish piece.

Another tip. When welding intersecting tubes, especially when at an
angle, weld in 1/4 round steps. Weld each side (ie, the tips of the
fishmouth) and let it cool. Then go back and fill in the crease.
Welding the sides first pull the tubes straight together, then the extra
material help to hold them in place when the crease weld tries to pull
them out of whack.

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