SPIRAL BOWL

MDF

I created the spiral bowl just to see if it was possible.

It is a difficult shape to mill for two reasons: the relative fragility of the medium (given the geometry), and the difficulty of securing the piece to the worktable. The piece has to be milled from two sides - the top and the bottom. (Even with a 5-axis mill this would almost certainly be the case.) This piece was milled from the top first. Once the inside of the bowl is milled out, there are few ways to secure the piece to the table so that the outside of the bowl can be shaped. I ended up securing the outer portions of the blank, but those portions eventually get milled away to leave the bowl, and thus I had to resecure the bowl behind the toolpath as it made its way across the piece.

The piece was more experimental than functional. Having proved the concept, it would have been possible to recreate the bowl in a more permanent medium such as a cast polyurethane, at which point of course I would have run a much tighter toolpath to get a finer finish.

I think it would be even more interesting to mill it from casting wax, to be forged into bronze or copper.