2008 2500 170" EXT
Only 10 series can be tapped as it has solid (not pre-holes) material, 15 series already has trapezoid voids that can't be tapped.I really like GeorgeRA's solar panel cross bars made of rounded 80-20. I want to make some custom end brackets but need to know if the 80-20 can be tapped in the corner 'holes' rather than the center. If so, what thread size would be appropriate?
Using 10 series, I'd only tap one as the maximum dia. is abooot 0.1 inch, and only to the keep the bar from twisting, and in conjunction with the main or middle hole which offers very good fastening strength. Even using three tiny taps would not need my requirements for longevity.