Intro: Impossible Joint (Osaka Castle-Otemon Gate's Pillar Splice)
Step 1: Male Part Marking
Firstly make sure you print the plans I provide and scale them up or down if your wood pieces are different in dimensions than mine.
Mark out all the sides of the wood piece according to the plans.
Step 2: Cut the Male Part
Use a hand saw to cut the male part. With a chisel finish and clean up if necessary. Make sure you stay outside the lines so you have the space to work with your chisel.
Step 3: Mark the Female Part
Again mark the female part according to the plans. For a better fit you can always measure the male part and mark the female accordingly. This will eliminate any misalignment between the male and female part.
Step 4: Cut the Female Part
Again with your hand saw carefully cut just a tiny bit inside the lines. Then clean up with your chisel.
Step 5: Finished!
For this project I used two pieces of pine. In order to make a better contrast between the two part I used a brown wood dye on the female part.
To assemble the two pieces just push diagonally the female part on the male part. Make sure you have a tight fit and adjust with your chisel if needed.
You can always check here for more info on Japanese Joints.