Grafton wall clocks were sometimes called Willard experimental clocks or Willard timepieces. These small clocks were usually made in Grafton, Massachusetts, although some were made in Roxbury, Massachusetts. They were produced during the last quarter of the 18th Century.

Grafton wall clocks are great rarities that were developed by Simon Willard and his brother Aaron Willard in an attempt to produce a small wall clock. These clock we often called "Experimentals" as they are the early attempts by Simon Willard to develop an improved timepiece. Each one of these early clock is slightly different, reflecting Simon's attempts to refine the form. The result of these experiments was the effective and revolutionary banjo clock or patent timepiece and its close kin, the Mass. shelf clock.

The early Simon Willard and Aaron Willard time pieces appear with brass dials and often have a passing strike. These Willard thirty-hour wall clocks are among the rarest of all important American clocks.