Locking Wall Measurements - Round Structure

[Daystar_Design]

Hello,

 

I'm drawing a round home with a 46' diameter.  The home has 18 wall sections.  I have all of that figured out and each wall section is 8' in length.  I need to lock down the measurement of 8' for each wall section however no matter if I lock the start, center or end, the adjacent wall always adjusts a fraction of an inch.  Does anyone have any suggestions to get each wall to remain at exactly 8' ?   Thanks !  Much appreciated.  

1263 Camino Monte Y Cielo Addition 040721.plan