To build the Rudder I chose to use a dimpling tool I bought from Aircraft Tool Supply on the recommendation of a coworker who built a Thorpe T-18. It looks like a Rivet Set except that it has a pivoting receptable with a 100-degree countersink and a hole for the rivet shank. So the process was to tape all of the rivets in place, lay the stiffener on top with the rivet shanks poking through, use the dimpling tool to dimple the Rudder Skin and stiffener then follow it with the back rivet set. I installed all of the Rudder Stiffeners in this manner.
