Join Date: Dec 2011
Location: La Grange, Kentucky
There a couple of options to the power tool techniques that have been discussed so far. I mention them because the power tool techniques are finicky and often do not yield the desired results. But, if you develop hand tool skills and learn to use them properly, them you will come to understand better how things go together plus you will have another arrow in your quiver that you can use when you need it.
The first picture shows a bookcase that I am building. The corner is a mitre joint, right? Look at picture 2. The corner was dovetailed with a mitre at the front end. An advantage to this corner is that it goes together at 90 degrees every time!
The third picture shows a mitre joint that was laid out and cut with a backsaw. No mitre box, no jigs. I know that this is not the joint you are trying to do, but it demonstrates that you do not need power tools, jigs, etc to do mitre joints. BTW, you are looking at the plinth for the book case.