Bullshit grinder

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A bullshit grinder. The crank handle is confined to ellipsoidal motion around the block via the linear motion of the shuttle pieces in the grooves.

The Bullshit grinder, also known as the Do Nothing 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 ellipsoidal 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 routed grooves. The mitered grooves are made in such a way that the sliding shuttle parts are captive and can not 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 a circular motion. As the handle is turned, the shuttle parts slide past each other almost effortlessly, achieving absolutely no purpose other than entertaining the operator.