To Dimple or Countersink the F-730 for AD3 rivets?

Hi Guys (and gals I presume),
I'm a bit embarrassed to ask this newbie question, but I've been away from the project for a long time, and I've also got a dead battery in my broken dial caliper... Here it goes..
I'm putting the F-730 reinforcement plate together with the F-728A and F-729A elevator belcrank ribs.
For the AN426AD3-(x) rivets do you simply machine countersunk the F730?
If you dimpled it, then did you dimple or machine countersink the pieces underneath...(F-728A and F-729A)?
If I recall correctly, the tipping point between machine countersinking and dimpling is when the aluminum is about .040" thick. Alas I have no accurate way to measure the thickness at the moment.
Thanks in advance,
Steve Wolfe
RV-7 tip-up Slow build..reeaally slow
Fuselage bulkheads in the works.

Dimple

The parts you list are .032"
Dimple.
If you have the fwd and aft canopy deck rails nearby, they are .040".

Thanks

Thanks Wirejock,

I'll find those fwd and aft canopy deck rails to use as a reference until I get a replacement micrometer type guage.

Steve