This is a custom joint for a table leg I am making. I made the grooves with router jig I made to make the shape.
The most important thing is to make sure all of the measurements are the same on each side. 
The legs were fit (pounded) in so tight that I did not use any glue or screws to hold them and they are very sturdy.
All the legs are put together now and I need to sand and finish the table, hopefully by the end of the year.
I love it! Furniture making is one of my activities too. I will be following you, great post
Is that mahogany?
It is Sapele wood but very similar.