set

A set is a steel or timber block positioned on top of a pile to receive the hammer blow when the pile itself sits too deep or too far below the driving frame to hit directly. It absorbs the shock of impact and transfers the force evenly to the underlying pile, protecting the pile head from splintering or crushing under repeated hammer strikes.

Sets come in two main materials. Steel sets, typically cast or fabricated from solid bar stock, are used for heavy-duty driving of steel piles and in marine or high-energy applications. Timber sets, usually blocks of hardwood like oak, are more common in construction driving of timber and concrete piles. Timber sets are cheaper and easier to replace after wear, though they deteriorate faster under sustained driving. Most sets are roughly cuboid, ranging from 12 inches to 24 inches on each side, sized to match the pile cross-section or slightly smaller.

The set becomes necessary in confined spaces, deep leads, or when the hammer stroke cannot reach the pile head directly. Rather than extending or repositioning the frame (which is costly and time-consuming), the operator places a set on the pile, then drives through it. This is standard practice in sheet pile driving along existing structures or in dense clusters where clearance is minimal. The set rests on the pile by gravity alone and typically sits for minutes or hours before being retrieved or knocked aside.

Repeated hammer impacts crater and splinter the set, especially timber versions. A timber set may remain serviceable for 200 to 500 blows before it becomes too damaged to distribute force safely; driving then concentrates load on the pile head rather than spreading it. Experienced crews track set condition and have replacements on hand. Failure to change a badly worn set risks pile head damage, reduced driving efficiency, and bent or broken pile sections.

The term "set" in this context comes from its function: it is set in place temporarily to serve the driving operation. It is distinct from a "dolly," which is a plate between the hammer and the set, and from a "follower," which is a tube or bar extending the reach when the pile is too short. In modern pile-driving vocabulary, the set remains a standard and indispensable component of the driving plant.