Some of the literature on violins suggests that the shape of the cross-section of the top and back is based on cycloids. Whether this is actually true is a matter for debate. Certainly much of the shape of a violin can be generated from circles so it is certainly possible that the masters based the shape on a cycloid which is generated from circular geometry. However, some modern makers say that they shape the top until it looks right rather than until it matches a template, so requiring the shape to fit precise geometry is probably requiring too much precision from the process.
Regardless, here is a script to generate the shape of the top of an arch-top string instrument using curate cycloids. I’ve written it in Python. I’m not experienced in Python so please excuse any errors and let me know how it could be better in the comments below.
The script takes in a PNG file that holds the shape of the long-arch down the centre of the instrument, plus the shape of the edges of the curved section. Using a PNG to hold this information means you can generate these curves however you like.Continue reading