There are a number or holes required for this project. Here’s a list of purpose and sizes. Galileo = 1 1/2”, Dowels = 5/16”, Magnets = 10mm, Clock/Instruments = 2 3/8”, back air holes 3/4” to 1”.
Here’s how I usually set the depth of cut. Instead of measuring from the top I set the drill to stop a distance from the bottom.
To locate a centerline I usually rip a piece of scrap and butt the part up against a stop so both are flush to the edge.
I drill all through-holes through both parts at the same time. The Galileo access hole is through the inner top and 1/4” into the inner bottom (see setting depth of cut above).
And here are the inner top and bottoms with holes. The only drilling left are the matching holes drilled into the wings for the dowels. This time around I am finishing the parts and leaving this step for last so I can drill then glue at the same time. I’ll let you know how it works out.
-- tim hill www.newcalshop.com