Plug and feather

Plug and feather

Various examples of plug and feathers
Other names	Feathers and wedges Wedges and shims Plugs and wedges

Plug and feather, also known as plugs and wedges, feather and wedges, wedges and shims, pins and feathers and feather and tare, refers to a technique and a three-piece tool set used to split stone.

Each set consists of a metal wedge (the plug), and two shims (the feathers). The feathers are wide at the bottom, and tapered and curved at the top. When the two feathers are placed on either side of the plug, the combined width of the set is the same at both ends.

Multiple sets of plug and feathers are typically used to split a single, large piece of stone. The stone is first examined to determine the direction of the grain. After the location of the intended split is chosen, a line is scored on the surface of the stone. A number of holes are then cut or drilled into the stone face along the scored line approximately 10 – 20 cm apart. Plug and feather sets are then inserted in the holes with the "ears" of the feathers facing the direction of the desired split. The plugs are then struck with a small stone maul in sequence. An audible tone from the wedges changes to a 'ringing sound' when the wedges are tight. Between each series of strikes, a pause of several minutes allows the stone to react to the pressure. Eventually a crack appears along the line that was scored on the surface and the stone splits apart.

Variations of the plug and feather method have been used since ancient Egyptian times. With this simple mechanical technique, the stone was first measured and marked. Bronze plugs and feathers were then driven into grooves which had been previously cut with a chisel and mallet.This was the most common method used by the Egyptians for quarrying limestone and sandstone. Evidence of this method for cutting obelisks in the quarries of Aswan can clearly be seen. The technique was also used by the Romans.

On Dartmoor, Devon, England, the process is known as feather and tare and it was used from around 1800 to split the large blocks of granite found on the ground there. It was, for instance, used to make the rails for the Haytor Granite Tramway in 1820.