INTERSECT is NOT accurate...by between 0.011" & 0.014"

I handle the creation of production files for a sign company. We recently began work on a very large scale monument with a 44' radius top. I used INTERSECT to create the panels to be routed for that portion only to constantly come up with an incorrect size (top to bottom) on the radius of each panel. On closer inspection I realized that whenever I used INTERSECT to create the panel for some reason it creates a flawed section off by .013" all the way across the shape. My understanding has always been that INTERSECT is supposed to create an exact section from the two overlapping shapes selected but that is now apparently not the case. This seems to only be the case with very large scale vectors in 1:1. It works perfectly with small scale shapes and creates a section exactly the size of the overlapped sections...but the larger the shape the greater the size discrepancy. Has anyone else encountered this issue and/or know a fix for it?