Good advice! Question: will the outside face of the aprons be flush w/ the outside face of the legs? Or will they be "set back" slightly?Bill[/QUOTE
If the tenon is centered in the apron stock thickness, then the placement of the mortise on the leg stock will determine if the apron is flush or set back.
Personally, I prefer the aprons to leave a reveal where it meets the leg, usually 1/4". If my legs are 1 3/4 square and the apron thickness is 3/4 then the back of my apron will be 1" back from the face of the leg. Meaning in this case, the back of the mortise would be 3/4" back from the face of the leg.
I have also made tenons that were flush with the back side of the apron with a thickness equal to 1/2 the thickness of the apron and leaving a shoulder on 3 sides of the tenon. This method gives you a heavier tenon and a deeper shoulder which may give a little stronger joint. In this case, the back of the mortise would be 1" back from the face of the leg.
More than one way to skin a cat.:gar-Bi
Jerry