As always in woodworking the first step is marking out. To form the tenon I needed to remove 6mm of material on each face, and 15mm at each edge. For this task I use a vesper marking knife, a veritas wheel guage, and a square. (See layout tips.)
The first cut is done with my 14" LN rip tenon saw to cut down each face.
Under the dust you can see I'm using a Bench Crafted vice in the sliding position to secure the piece. A simple tip from Derek Cohen (In the Woodshop) was to have the board at an angle away from me, changes the rake vs fiber angle, and greatly eased the sawing action.
Contrary to how this photos appears I do actually saw with my eyes open.
The next step, using the rip saw again, is to cut down each edge.
To remove the waste material at the shoulder, I secured the piece with a bench dog and hold fast, and used a cross cut saw to cut down the shoulder.
And there we go. One tenon ready for a little tidying with a rabbet plane for a nice snug fit into the mortise.