...Countersunk washers to clear Flat-Head Screw 'Cone' Taper. Cone is .200" Deep. 0.090" is taken up by the Sheet Aluminum. Can't Countersink the 'Beam', that would eliminate much needed threads. So I counter-sink the 0.121" Thick 1/4" Washer, 0.110" Deep, The Just clear...with a couple of 1000th's more, for 'Crush' on the Louver.
Look Close at the Height/Spacer Assembly. With the screw thread into the Beam a Minimum of 0.240" IN, it gives a Height of 0.750", measured from the Beam to the TOP of the Louver, Maximum. If I need more Height, I change the 1" Length Screws for 1-1/4". See Countersunk washers, and (2) Flange Screws, Jam Nut set-up. Easily Adjust the Height to '0' on the Inclinometer At X and Y, and Lock it In!! Job Done!!