Prepping aluminum parts - corners and faces

[dxlusby84]

Greetings builders,

Some of you may be familiar with the homebuilt HELP series. One of his videos is on polishing aluminum parts (really Deburring and beautifying, I'd say)... In the video below, at about the 2:20 mark, he goes through the process of rounding off the corners and polishing up the faces of the aluminum bracket he's showing...

Ignoring the obvious benefits of deburring, my questions are these: Is processing the parts like this adding any engineering value or is it all aesthetic? Would you do this on all interior parts, from the smallest brackets to main spars for the flight surfaces? He mentions places where corner rounding would NOT be advised, but doesn't really explain why - anyone have a guess?

And finally, aside from edge deburring, how have you all prepped your factory aluminum parts before assembly?

https://youtu.be/JdBA4BCsQ0M

Thanks,
Devin

[Bryan Cotton]

As a minimum, you need to smooth cut edges. Includes extrusions as well as sheets. Anything sharp is a stress riser and a place for a crack to start.

But what about the smallest bracket X that has no load? It comes down to your workmanship standards. Maybe I'd slap a gouged bracket on my golf cart to hold a headlight, but the same bracket on the airplane will be cleaned up and smooth.

Make friends with your files. The scotchbrite wheel on the bench grinder is a time saver. Maroon scotchbrite pads are also awesome.