I didn’t’ take a picture (edit—but I went out and took one just now) of it but I made a quick jig of a piece of 48”x6”1/4 left over and a scrap same width as my “TRUE” wood edge (need a piece of the REAL wood not metric or 1/16ish off crap they sell) the JIG is essentially a “T” that is nailed true to square…
The photo got cropped a bit but look to the right and you will see the routed out 3/4 Dado in the jig that is the “sight” you line up with your shelf dado.
- Cut them BOTH at once ** Important part here—When you make parts with Identical joints you GANG them all together so that they are all alike.. I did the same I clamped the two outside case panels so that the were “booked” and then clamped them.. (booked laying out back to back).
Then fire up your router (With the Bit your going to route out your shelve joints in this case 3/4”) and you carefully route a Dado thru the jig, use another scrap as backing and clamp it all down.
Now you have a guide that you simply line up with your shelf dado marks.. and glance thru the JIG, Clamp it down and you cut them.
In the end you have two sides that you can tell yourself are perfectly aligned and are Dado’ed Perfectly…
-- Duct Tape is the Force! It has a light side and a dark side and it Binds the Universe together!