It's been about eight years since I built a Jazz archtop and a lot of interesting new ideas have come up in that time. I thought it would be fun to try some of them out, and add another instrument to the roster of the Seasons presentation series.

   Most of the “new” ideas are (maybe) old ones in some sense. In the past few years Quentin Playfair has been working on a system to draw the cross arches of fiddles. He maintains that the “Old Masters” used a curve based on “curtate cycloids.” Cycloids were the “sexy” math a generation before Strad since they're the basis of Ptolemaic astronomy. You draw cycloids by rolling a circle along a surface, and tracking a point on the edge (for a “regular” cycloid) or somewhere inside (for the “curtate” kind). Using this technique it's easy to draw out cross arch shapes using only simple shop tools and no math in particular. And they look great.

   Other violin researchers have noticed that the Old Boys used several systems of aching over the years, and each arch system has a different top graduation scheme that goes with it. The curtate cycloid cross arch seems to “belong” with a uniform top thickness, so that's what I did here.