This project was my first introduction to CNC machining. During this time, SolidWorks had a HAAS OM-2 on loan, and Charles Davis at HSMWorks was kind enough to give a number of us an introductory course in CNC. The learning curve was extremely steep, but with the HSMWorks software and a few late-night emails to Charles, I was able to generate the toolpaths and machine all of the parts of the fingers.


The finger parts were designed in halves, with all surfaces machined. While the outer surfaces are organic 3D profiles, the inside surfaces are planar, which allowed me to fixture to them.

I first machined a fixture plate parallel to the mill table, with two precisely-placed 1/4" pins and tapped holes for hold-downs. This would allow me to flip the workpiece over (to machine both sides) without having to re-indicate.


Toolpaths were generated using high-speed machining techniques with HSMWorks. The constant-engagement climb-milling toolpaths allowed me to get the most from the HAAS's 30,000 rpm spindle and relatively rigid table. The vast majority of the cutting was done with 1/8" end mills -- flat for roughing and ball for finishing. End mills of 1/8" and 3/64" were used for fine detail work where required. Roughly 5 sizes of drill bit from #52 to #40 were used as well. Roughing was done using the HSMWorks Adaptive Clearing technique, while finishing was accomplished predominantly with Contour toolpaths for steep faces and Parallel paths for shallow ones.

An early test cut showing two connecting links.

After roughing.

The parts for one finger.

The HAAS headstock, cover removed. At 2AM one night, the spindle stopped releasing tools smoothly. Adding a shim got the machine working again.

The final product, after media blasting and anodization. Junctions between finger joint halves are barely visible.