Graham calls this touch probe his first useful milling project. He had already built the CNC mill and once he built this probe on the mill he essentially had a 3D scanner. The central hub is supported by three shafts spaced evenly around its axis. These shafts each rest on a pair of ball bearings to make a complete circuit. If the probe bumps into anything, one of the shafts will lift, breaking the circuit. TurboCNC has a built in routine for scanning with a touch probe. The program generates a point file which Graham pulled into Rhino for modeling. His example application was cloning a model airplane prop that had gone out of production. The TurboCNC routine isn’t very quick since the probe always returns to the same height so he’s coding a faster algorithm. This type of touch based scanning was also employed in agiecco’s LEGO 3D scanner.