Good Aftenoon Friends,
I have made a jig that helped me in making a Greene and Greene Style table mortising the spline joint at the table edge and breadboard end and I thought that if any of you folks are interested just contact me via email and I will send you some drawings.
Here are Three pictures of the jig;
The first one is an overview, the second one is the back end of the jig and finally the last one is showing the front end. Notice the stop for the router to be in the correct location to start the mortise. You will need a spiral up cut bit.