peg
楎 centers on a peg: a small wooden pin or dowel used for fastening or hanging things.
楎 combines 木 (tree/wood) with 軍, which likely contributes the sound. The character originally referred to a wooden peg or clothes-peg.
The left side 木 is wood, and the right side 軍 suggests something sturdy like an army. Picture a strong wooden peg holding things together like a disciplined soldier.
For コン, imagine a wooden peg shaped like a cone: cone -> コン, and the peg fits snugly into a hole.