This rudder stop on a Kitfox was barely touching the rudder horns and was close to imminent failure, which could have caused binding of the rudder, most likely at the most inopportune time. Welded tabs used as control stops on tube-and-fabric aircraft such as these are fine, but they usually require some fine-tuning once the aircraft is completely assembled.
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Metal Magic: Intro to Riveting
Introduction to driven rivets. Learn how to judge the size of rivets you need and how to tell if you've driven them correctly.
Aero ‘lectrics
Heat and avionics don't get along all that well. Rather than installing a fan that runs all the time, Jim Weir suggests building and using a fan that runs only when you need it.