Hard Drive Centrifuge Rotor (secure design)

My lab has been in need of a compact centrifuge for 1.7 mL Eppendorf tubes.

From the work by KemFic on a DIY Arudino powered centrifuge from old hard drive spindles, I modified the design for a more secure structure and fit on a standard 3.5" hard drive (molded to the spindle shape and screw-hole locations). The resulting structure is more stable at higher RPMs.

The code has also been modified (https://github.com/ekurt1/Hard-Drive-Centrifuge), with automated and manual speed calibration