Chuck Wilson said:
do you mean making the holes?
it's complex to explain, but simple in reality, and it didn't take more than 10 minutes to make them.
i first made the torsion box top wich consists of a 12mm sheet below, then a series of vertically placed mdf strips (30mm) and then a 18mm top. the top is screwed but not glued so it can be replaced.
this sandwich is virtually (almost) undeformable and is as flat as can be.
then i made a jig (in green on image) a simple piece of mdf, with strips at both ends to keep it paralel. on the jig i made a line every 96mm, all i had to do was align the centerline of my router to the line on the jig. i used a 20mm bit and i think it is pretty much ruined after making those plunge cuts.
inside the torsion box there are also beechwood blocks into wich the top and oak egde are fastened. mdf alone is not strong enough for that.
i have already discovered a flaw in the system, the torsion box is not deep enough for the festool clamps to get in the holes. i will add a T-track on the top of the oak edge aswell so i can clamp stuff on top.