Step 6 : create the main rafter (in a new body)

In a new sketch created in the YZ plane, and after making the "SketchRoof" master sketch visible, create a carbon copy of this master sketch, then fit it to the outline of the main rafter.

Create a symmetrical extrusion with a length equal to the thickness
of the main rafter

      <<SketchOpening>>.Constraints.SandpitThickness

In a new sketch created in the YZ plane, and from the "SketchRoof" 
master sketch, create the geometry of the receiving mortise the truss beam.

Create a pocket by symmetry of the thickness of the tenon of the truss beam
(30 mm)

In a new sketch created in the YZ plane, and from the "SketchRoof" 
master sketch, create the geometry of the tenon of the main rafter.

Create a symmetrical extrusion with a length equal to the thickness of the tenon
(30 mm)