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Precision in our Homebuilt

dsnaproll

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The Methods we use in building our aircraft and making subtle little changes, alterations or modifications, can have drastic effects for the good and for the bad. Just by adding something as simple as a a wing root fairing, can give you good or destructive flying characteristics.

I view our builder's Gallery frequently. I have seen different ways builders have made and used jigs. That is my main focus in viewing the Gallery. Also I have seen the Methods or Practices that they employed.
There are a few topics I would like to highlight in our "Precision building".

Cutting Bearing Shoulders;:

20071028_100045_bad1.jpg


It is not necessary to chuck your part in a Lathe and make it perfect. The same can be accomplished by cutting your Shoulder Bearing straight and butting it up to the Bearing and then weld.
This is a Very Bad Practice to cut the bearing shoulders straight with a Lathe after it has been welded in place.
IF you can cut the part without cutting, nicking or scratching the underlaying tube, that would be OK. But I do not think it is possible. Even if you stop short and finish with a File, you will scratch or cut the underlaying tube with the File.
This is a perfect setup for future "Stress Riser Cracks" by the twisting and bending forces of the rotating Torque Tube.

Welding Bearing Shoulders:

It is also not necessary to weld the Bearing Shoulders completely all the way around. In fact, I it would be contrary to good Building Practices. Again, this is a perfect setup for future "Stress Riser Cracks" by welding the entire circumference perpendicular to the tube, inline with the rotational force. Four to Five 1/4" welds around would be sufficient. If you just need to weld it all the way around, make your Bearing Shoulders with a Fish Mouth on the outside. A Fish Mouth cut not only gives you a bigger area to weld but also keeps your welds off of parallel to your rotational forces applied to your control.
 

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