Hi, 
  
I am working on a basement design and there are 6 support posts running down the center of the room.  I could not find any appropriate items, so I placed them using a cylinder shape, however I can't seem to get the measurement tool to show dimensions between the posts in order to properly place them.  Is there a better element that I should use, and is there a way to lock them in position so that they don't move when I place walls and build out the space? 
  
Thanks 
Al