# CNC Sine Waves

Little experiment creating a bowl inspired by a damped sine wave – something like a ripple on the surface of water.

Carved in spalted beech (spalting is when a fungus has fed on the nutrients in tree and discoloured the wood), I think the black line gives it a really dramatic look.

I carved this with a 6mm ball nose bit on my CNC machine, with the finishing mostly done by hand sanding. It still needs final smoothing and then to decide what finish to go with – I’m thinking Danish oil, but perhaps a high-gloss varnish or oil might be better?

Designing the bowl involved created a 3D model first. I sketched a graph based on the formula below , and then tweaked the inputs to match the size of stock I had available.

$y(t) = e^{-\gamma t} \alpha cos(\beta \pi t)$

Then it was pretty straightforward to take the SVG of the graph into Fusion 360 and create a revolved body from it. The centre of the ‘ripple’ is offset from the centre of the stock to allow for more of the ripples to cascade.