Brief Description: Rib Flange Centreline Making Tool
Constructing the Empennage, and later the wings, involves drawing a centreline on the rib flange (5/16"). Unable to find photos on the web I made this. I'm sure there are better ways but its good enough for me.
"Better is the enemy of good enough" USSR Naval Commander 1970's
ADDENDUM
When you come to mark the centreline of the Z brackets that support the fuel tank to the main spar they happen to be the same width! All I had to do was cut the wood slightly - so don't discard it!