Montagnana Arching

I did some work with the cycloid program. First I made some long arches for the belly that will cross, and create the final long arch. It is a combination of these arches and the width of the cross arches that define it. It seems like the result will be almost exactly a circle. Cool. I did the same with the back, but for that there are two aches that don't make it the entire length. These I scaled at 270 long, so they come out to the sine of 51.8 degrees, another golden number. (273 works too, using the mold length and not the length from block to block, another golden number)

For some reason Dominico shifted the thick point quite high on the back, yet the long arch still appears to be a circle. If we make the top arching .3-.4 shallower, and make the top thicker and the bottom thinner, we get the results we want. Maybe he was trying to loosen up the bottom, maybe he was trying to stiffen the top. Whatever the reason the middle is thick, but not the thickest area.

Checking the cross arches I found that the line I was using for the cross arch width was off. Making the line where I had it, the wide thin area in the bouts around the edges could not be that thin. I had to re-draw it in red. The belly arches from the poster match the cycloid ones I drew up, (well the computer did), and I marked out the inflection line, where the arch will change from convex to concave. The back arches match quite well also, except for the one on the lower bout, were it seems it could have been arched too widely on the inside, and ended up a little fuller than the cycloid came out. The archings are quite thin in many places, and I don't think I went that thin on my other one. I really need to take notes.

I was going to make it with 19.5mm and 16mm arches, then I thought to make them original 19.9mm and 15.6mm.
Now I've decided to use 19.5mm and 15.75mm. Why? They come out at a ratio of .809, so why not? I'm also making the mold the same length as the del Gesu, because the lengths were given over the arching, so 352 long is more likely.