Originally Posted by TJones
A rivnut would be much stronger. A self tapping screw or bolt will not hold much on thin sheet metal.
Ted is correct! [ applause ]
A bolt into a nut has >three or four or five+ turns to snug.
A screw into sheet-metal has part of one turn... the thickness of the sheet-metal (16-gauge?).
If your roof was 1/8-inch steel plate, your screw might 'bite' a turn, turn-and-a-half.
Most roof material is less than that, much less.
A bolt-n-screw combination is engineered to slightly stretch under the load of proper torque, smushing the threads into an almost-welded condition.
A screw into sheet-metal will pull out before any adequate torque is reached.
A bolt-n-screw combo is engineered for a load parallel to the bolt shaft.
With a screw into sheet-metal, you are the engineer (aka 'test-pilot').
The way I see my purpose on this forum:
* I am here to suggest alternatives to costly learning experiences... injuries to your wallet or to your delicate sensitive favorite flesh.
Me puncturing holes in your carefully-crafted plans doesn't bother me a month-old Twinkie©.
Listen, do not listen... either way, I am good.
I may come across as a cranky old know-it-all... only because our time together is limited.
That, and this whole 'bus fiddling with' is supposed to be fun... and chasing treasured chunks of equipment after it leaves its home at high-velocity -- often with great ceremony and to the delight/dismay of innocent by-standers -- is less fun than it sounds.