Carving the belly
I ordered the Englemann Spruce top from Mountain Voice Soundwoods.
I tried a different approach to give me the correct contours as per "The Secrets of Stradivari" by Simone Sicconi.
Since the drill press worked good to follow the contours for gouging out the back, I thought it should work in reverse to create the correct contours for the front.
Tracing the contour lines onto the belly and then setting the depth stop corresponding with each line, I drilled 1/8" holes just slightly less than the plan to allow for planing.
Jim Novak gave me a full sized copy of the contours, which I laid on top to check my measurements precisely. There was no guessing.
Looking from the bottom.
Looking from the top.
As you can see they turned out very symmetrical.
Now it was time to hollow it out.
I set up a simple depth gauge for the drill press, set the stop at 3.5mm, the same technique as I did for the back, and started drilling holes.
The plate thicknesses where of the Stradivari design, taken from Simone F. Sacconi "The Secrets of Stradivari" book The goal thickness are 2.7mm near the "f" holed and 2.4mm elsewhere.
The spruce was very nice to work with. Using a sharp gouge chisel, I roughed out the belly almost down to the bottom of the holes. With the thumb planes, finished it down to the desired thickness.
As I did with the back, when getting close to the proper thicknesses, I would check the tap tone. Holding the back by the upper left corner between my thumb and fore finger, lightly tapping the middle of the plate with my knuckle, I would listen to the tone of the plate. Taking more wood out to raise the tap tone to the desirable frequency of the belly plate. The desired frequency should be 1 1/2 semitone lower than the back. F# for the back and E for the belly.