finger grip

A finger grip is a mechanical overshot device lowered into a borehole on wireline or cable to retrieve rods, tools, pipes, or other objects accidentally dropped during drilling or well work. It consists of a cylindrical body with spring-loaded or hinged fingers (usually four to six) that grip the exterior of the stuck object when the tool is lowered over it and tension is applied. The operator works from surface, feeling feedback through the cable tension to confirm a solid catch before hoisting the lost item back to the top.

The tool sits in a family of fishing gear used across oil, gas, geothermal, and mineral drilling operations. Related devices include overshots (which slip over a fish), spear tools (which penetrate into hollow pipe), and jars (which create sudden impacts to dislodge stuck equipment). A finger grip is chosen when the lost object has a smooth external diameter and when the operator needs a non-destructive recovery method that minimizes damage to the stuck item.

Finger grip design varies by bore diameter and object weight. Standard industrial models typically handle retrieval depths of 500 to 5,000 meters and fish weights up to 2 to 5 tonnes, though custom heavy-duty versions exist. The fingers are usually hardened steel and must grip firmly enough to sustain the load on the cable without slipping, yet release without gouging the recovered object. Smooth bore walls and objects free of tool joints or shoulders work best; rough surfaces, accumulated scale, or tapered geometries reduce holding reliability.

The main failure mode is finger slip, where cable tension alone does not create enough mechanical clamping force. This occurs if the object diameter does not match the tool's design range, if the bore wall is heavily corroded or encrusted, or if the operator applies tension too slowly and the fingers cannot lock. Overuse also wears the finger contact surfaces and springs, reducing grip security over time.

The term finger comes directly from the tool's mechanism: the small hinged or spring-loaded arms that mimic the motion of human fingers closing around an object. Grip describes its function. In some regions or older texts, the tool may be called an overshot or fishing overshot, though that term technically describes the broader class of tools that slide over a fish rather than into it.