Radius at the corner of a metal cutout?

[Steve Crewdog]

I know you should not have a perfect right angle because it will lead to a stress fracture, but how much of a radius do you need? I'm cutting the opening for my Dynon D1000, don't want to make the radius too big or it will show, but if I make it too small I don't want a fracture to develop in my panel.

Thoughts? TIA.

 

[PaulvS]

Radius

I've used 1/8 final radius without any problems. Radius can be reduced a bit if the display corners bind. I initially drill the 4 corners with a step drill to 3/8" or 1/2" (to allow for the saw blade) and then finish with a 1/4" or 3/16" chain saw file. I also do the final sizing of the straight edges with a file for the last 1/16" or so. The openings need to be cut very precisely because some of the Dynon units have only a narrow lip.

 

[Steve Crewdog]

Thanks Paul, that's about what I was thinking but wanted to be sure that it didn't have to be big and dramatic.