Slip-joint pliers

How it works

Two levers cross at a pivot; squeezing the handles closes the jaws, and because the jaws are short and the handles long, the grip of the hand is multiplied at the work. On slip-joint pliers the pivot pin is fixed in one lever and passes through a shaped slot in the other. Condit’s 1903 patent describes the “well-known class of combination-tools” in exactly these terms: a pivot fixed in one member and moved in a slot in the other to vary the capacity of the tool.

To change the setting, the user opens the handles wide and slides one lever across the pivot into the other end of the slot, then closes the tool again. Bernard’s 1917 patent describes the operation: in one position the jaws meet, in the other they stay apart when the handles close, and to change from one to the other the tool is opened and one lever is shifted transversely relative to the pivot. His slot has two enlarged round ends joined by a narrow neck, and the pin has flats that pass the neck only when the tool is opened fully.

The jaws usually combine flat serrated tips for small parts with a curved, toothed section behind them for round stock. Condit’s 1903 patent shows nipper teeth and pipe teeth on the same jaws, with wire-cutting notches around the pivot that come into register in one setting or the other.

Anatomy

Handles (levers): Forged steel, often with a gripping pattern; Crescent’s “Checkerdot” pattern is one example recorded by Alloy Artifacts.
Pivot pin: Fixed in one lever; on Bernard’s 1917 design it has a head set flush in a countersink and flats that fit the slot’s neck.
Slip-joint slot: A slot in the other lever with two seats for the pivot, giving two jaw capacities.
Flat jaw tips: Serrated faces for gripping small or flat parts.
Pipe grip: A curved, toothed section behind the tips for round work; Condit (1903) calls these pipe teeth.
Wire cutter: Shearing notches near the pivot on many patterns; Condit (1903) and Kellemen (1909) both patent forms of it.

Variants

Standard combination: Flat tips, pipe grip and cutter; Crescent’s first slip-joint pliers were of this style, according to Alloy Artifacts.
Universal combination: A Crescent style with both flat and curved gripping surfaces, offered by 1914 according to Alloy Artifacts.
Thin-nose and bent thin-nose: Slimmer jaws for confined work; Alloy Artifacts records Crescent offering a bent thin-nose style by 1914.
Flush-pivot slip joint: Bernard’s 1917 patent sets the pivot head flush so the jaw portion is thinner and reaches into tight spaces.
Multi-position tongue-and-groove (successor): Channellock says its chief engineer developed multi-position tongue-and-groove slip-joint pliers in 1933. Treated as a separate tool in this archive.

Specifications

Overall length · in or mm: Sold by length; Alloy Artifacts records Crescent’s early “Simplex” pliers in 5, 6, 8 and 10 inch sizes. No standard size table has yet been sourced.
Jaw positions · count: 2Two pivot seats, as described in Condit (1903) and Bernard (1917).

Made to

ASME B107.500
ISO 5743
ISO 5746

Safety and care

Safety

Bernard’s 1917 patent notes that the protruding pivot of earlier slip-joint pliers made the jaws bulky and hard to get into small spaces; no injury or failure data has been sourced.

Tips

Move the joint to match the work
The manual states that the pivot of slip-joint pliers is used to adjust the jaw opening for large or small objects. Condit’s 1903 patent describes the slip joint as a pivot fixed in one member and moved in a slot in the other member to vary the capacity of the tool.1 2
Use the rod-gripping section for round stock
The jaws of slip-joint combination pliers have serrated faces for holding objects and a rod-gripping section built into the jaws.1
Cut only soft wire and nails
The cutting edge cuts soft wire and nails. According to the manual, cutting hard materials or large gage wire will spring the jaws and make the pliers useless.1
Keep pliers off nuts and bolts
The manual says not to use pliers for prying or for removing nuts or bolts, and to replace pliers with broken jaws, handles or cutting edges.1

History

Earliest documented

300 BCE–100 CE

Llyn Cerrig Bach, Anglesey, Wales

Amgueddfa Cymru – Museum Wales holds a pair of blacksmith’s long tongs of this date from the Llyn Cerrig Bach deposit, excavated in 1942–1943: two iron levers 405 and 420 mm long joined by a rivet. This is the earliest dated pivoted gripping tool read for this entry. The slip joint itself is documented only from the patent record; by 1903 a US patent could call it a well-known class of tool.1 2

Slip-joint pliers descend from the smith’s tongs, the oldest pivoted gripping tool in the archaeological record read here. The Llyn Cerrig Bach tongs of 300 BCE–100 CE are two iron levers riveted together, with handles of 405 and 420 mm against a mouth 85 mm long; the Breidden tongs have parallel gripping faces on bowed jaws. Pincers in the Science Museum Group collection from Persia and Italy of the sixteenth and seventeenth centuries keep the same plan of two crossed levers on a fixed rivet.

A fixed rivet fixes the size of work the jaws close on squarely. The slip joint answers that limit with a second seat for the pivot, so that one tool has two working ranges. By 1903 Condit could describe combination tools with a pivot moving in a slot as a well-known class, and the patents of the next fifteen years refine rather than introduce it: Condit adds cutting notches that register in either setting, Kellemen improves the cutter, and Bernard sets the pivot flush because, he writes, earlier tools of this general type were bulky and hard to get into small spaces.

The form spread with the motor car. Alloy Artifacts records that Crescent’s pliers of 1907 onward were almost all slip-joint, sold under the “Simplex,” “Motor Kit” and “CeeTeeCo” names, and that the company did not offer a substantial range of fixed-pivot pliers until 1926. Crescent’s own history says an adjustable wrench and slip-joint pliers were supplied with every Ford Model T. The pairing made sense for a kit tool: the slip joint and the pipe grip let one tool hold a small nut or a round fitting.

The multi-position tongue-and-groove plier, which Channellock dates to 1933, carried the slip joint further, from two pivot positions to several. O*NET’s Tools Used table lists adjustable widemouth pliers or combination pliers, the commodity classes that cover this tool, in 12 of the 24 occupations mapped to this archive’s trades.

Timeline

300 BCE–100 CE
Iron blacksmith’s tongs with riveted pivot, Llyn Cerrig Bach, Anglesey.1
Iron Age / Roman
Iron tongs with bowed jaws and simple parallel gripping faces, held by a dome-headed rivet, from the Breidden hillfort.1
1501–1700
Persian pincers of the 16th or 17th century, now in the Science Museum Group collection.1
1600s
Italian pincers of the 17th century, 175 mm long, transferred from the Victoria and Albert Museum to the Science Museum.1
c. 1870
A pair of pliers of about 1870 enters the Science Museum Group collection (object 1934-410).1
1903
Howard C. Condit patents combination pliers with wire-cutting notches arranged around a slip joint, describing the slip-joint combination tool as a well-known class (US Patent 732,715).1
1907
Karl Peterson founds the Crescent Tool Company in Jamestown, New York; Alloy Artifacts says its first products were essentially those of the dissolved J. P. Danielson Company.1 2
1908
Crescent offers combination pliers under the “Simplex” brand by early 1908, according to Alloy Artifacts.1
1909
Henry F. Kellemen patents cutting and holding pliers for Utica Drop Forge & Tool Company (US Patent 942,504).1
1913
Crescent introduces the “Motor Kit” and “CeeTeeCo” brands for its pliers, according to Alloy Artifacts.1
1917
William A. Bernard patents a slip-joint pivot with a flush head and a keyed pin, for a thinner jaw (US Patent 1,236,138).1
1926
Crescent acquires Smith & Hemenway and only then offers a substantial range of fixed-pivot pliers; its earlier pliers were almost all slip-joint, according to Alloy Artifacts.1
1933
Champion-DeArment’s chief engineer Howard Manning develops multi-position tongue-and-groove slip-joint pliers, named Channellock, with patent and trademark protection in 1935, according to the company.1
1957
Crescent marks its golden anniversary with engraved slip-joint pliers, one of which is held by the Fenton History Center.1

Gaps in the record (6)

The first patent or maker of the slip joint has not been found. Condit (1903) treats it as well known, so it predates 1903; nineteenth-century patents and trade catalogs have not yet been searched successfully.
No Bronze Age or Egyptian evidence for pincers or tongs has been read; the earliest object cited is Iron Age.
No published account of where the name “gas pliers” comes from has been located.
Crescent’s statement about the Ford Model T kit sits under a 1927 heading in its timeline; the years it covers are not stated.
No standard size table, care guidance or independent test data has been sourced; buying is null.
No disagreements between sources were found; disputed is empty.