stoper

A stoper is a handheld pneumatic drill designed to drill upward into an ore face, typically mounted on a flexible hose and operated by a single miner standing on a ladder or platform. Unlike a standard horizontal drill, the stoper fires its piston vertically or near-vertically, allowing miners to excavate stopes, which are the excavated chambers left behind after ore extraction. The tool weighs between 10 and 30 kilograms depending on the model and drives a tungsten carbide or steel bit into rock at 1000 to 2000 blows per minute.

Most stopers run on compressed air supplied at 5 to 8 bar pressure through a control valve operated by the trigger. The percussion mechanism strikes the drill bit many times per second while the miner applies downward force and rotation, either manually via a spline connection or through an integral rotation feature. Early stopers used simple reciprocating pistons; modern designs use ported cylinders and anti-vibration mounts to reduce operator fatigue on extended shifts. Feed control is critical: too little pressure and the hole advances slowly; too much creates dangerous recoil and destroys bits prematurely.

Variants and working conditions

Stopers come in several weights and bore sizes. A light stoper might use a 22 mm diameter bit and drill holes 50 to 75 mm in diameter; heavier models exceed 32 mm bit size. Jackleg models couple the drill to a rigid prop rod that braces against the floor, allowing hands-free operation once set. Drifters and stopers are sometimes used interchangeably, though drifters typically work horizontally or at shallow angles. Underground, stopers work in confined spaces surrounded by freshly exposed rock; wet stopes require careful water management to prevent bit jamming, while dry stopes generate explosive dust unless suppressed by water injection at the drill head.

Bit wear is a major operating cost. Tungsten carbide maintains hardness but costs more; ordinary steel bits are cheaper but dull quickly in abrasive granite or similar hard rock. Holes drilled with stopers are typically charged with explosive, so straightness and proper angle matter for blast geometry. A bent hole or one that deviates from plan can cause uneven fragmentation or create dead zones where ore remains unbroken.

The term stoper comes from the work of stopping, or filling, the voids created by ore extraction. The drill is the tool that creates those holes into which explosives are charged. Stopers represent one of the oldest categories of mining drill still in heavy use; pneumatic designs have changed little in principle since the early 1900s, though ergonomics and vibration control have improved substantially. In modern operations, stopers compete with and are sometimes replaced by larger production drills, jumbo drilling rigs, and long-hole drilling systems that can work from a single setup point. However, in narrow veins, shallow dips, or complex stope geometries, the stoper remains the practical choice because of its light weight and operator mobility.