Nothing grinder
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A Nothing Grinder, also known as a Do Nothing Grinder or a Bullshit grinder, is a toy produced by regional woodworkers in New England, and is often sold in gift shops.
The device is a classic example of adapting elliptical to linear motion along two axes. The base of the device is a square block of wood with two perpendicular routed grooves. Two shuttle pieces move back and forth in the grooves. The mitered grooves are made in such a way that the sliding shuttle parts are captive and cannot be removed. These shuttle pieces are attached by a pivot joint to the center and end of a lever. The unattached end of the lever has a handle which the operator turns in an elliptical motion. As the handle is turned, the shuttle parts slide past each other almost effortlessly, achieving absolutely no purpose other than entertaining the operator and tracing out a perfect elliptical path.
As a device other than a toy, the mechanism can in fact be used for something useful, such as drawing or routing ellipses, mainly in wood.
