Workshop

The latest DIY ideas, techniques and tools for the industrial arts from metal and woodworking to CNC machining and 3D printing.

CNC Milling a Spherical Ice Mold

CNC Milling a Spherical Ice Mold

We have covered these spherical ice molds before. I have used one, myself, and they work pretty well. A chunk of ice is sandwiched between two halves of a metal mold, and fast conduction of heat away from the ice, through the metal, causes it to melt wherever the mold makes contact. The mold halves slide on rods to maintain their alignment, and gravity does the rest. With a mold that starts at room temperature, it only takes a few minutes to make a nice shiny ice sphere.

The Tesla Valve: One Way Flow With No Moving Parts

The Tesla Valve: One Way Flow With No Moving Parts

Here’s yet another delightful mechanical curiosity from among Nikola Tesla’s nearly 300 known patents. Shown above is the sole drawing page from US patent #1,329,559, “Valvular Conduit,” issued 1920. You may have to stare at the upper section, for a moment, to figure out what’s going on: Flow from left to right, as illustrated, is against the valve’s bias—the stream is broken up and diverted in circular paths that return to interfere with each other. Flow from right to left, however, is not so impeded.