Thanks Bruce and Mike

Mike I am thinking of all the dovetailed and box joint boxes and exposed splined boxes being made ,what is the reason ?
You have a point and I have made some small boxes just gluing the joint but never felt comfortable doing it and its long term durability .
Take a drawer as a example I think that would be a perfect application for a key joint like this to add strength and durability .
Another advantage is during assembly all the parts align very easily.
I can think of other applications where this type of joint could be used and made very quickly with this jig .

Klaus