The bottom threshold needs to be a mirror image of the left side of the aircraft, including the stringer. Since I don’t have the stringers in place, I need to find the location of the stringer and measure as close as I can to get the proper distance. I used Russ Erb’s method by having a string between the top and bottom longerons and mocking up the stringer run. Amazingly enough, I came within 1/16th of the plans dimension. Using the plans would have been just fine, but this just confirmed the proper distance.
