Ball-peen hammer

How it works

The face end is swung square onto a punch or chisel, or onto work that is already softer than the hammer. Leonard’s machine-shop text says the face is made slightly crowned, or high in the center. Estwing says the flat face is for striking punches and chisels and the ball end is for riveting, shaping and straightening unhardened metals.

The peen end stretches and spreads metal. Leonard defines peen as the upper end of the hammer, used in riveting, and as a verb meaning to stretch by hammer blows, as in straightening a shaft. A machine-shop rivet is usually riveted cold: one end is hammered down to fill a countersink while the other end is supported on an anvil or another suitable means.

The hammer is made hard at both ends. Leonard says hammers are tempered at each end about as hard as they will stand without breaking, with the eye left soft. That hardness gives the face its life and also makes it able to chip when struck against another hard tool.

Anatomy

Face: The flat striking end, slightly crowned, with a beveled edge on modern hammers. CCOHS says beveled faces are less likely to chip or spall.
Peen: The rounded end shaped as a ball, used for riveting and for stretching metal. Straight-peen and cross-peen hammers carry a flat wedge in its place.
Eye: The oval hole for the handle. Leonard says it is flared larger at each end than in the middle and is left soft when the hammer is hardened.
Handle: Hickory, fiberglass, or steel with a grip. Leonard says the handle is smaller in section near the head so that part of the shock is neutralized.
Wedge: A small metal wedge that spreads the end of a wooden handle into the flared eye; Leonard says the wedge should be nicked like a rasp so it does not jar loose.

Variants

Straight-peen and cross-peen hammers: Leonard and Kaup describe the three ordinary machinist’s forms: a flat peen parallel to the handle, a flat peen at right angles to it, and the ball peen.
Machinist’s chipping hammer: Listed separately from the ball-pein hammer in Sargent & Co.’s 1869 catalog under Maydole’s cast steel hammers, in sizes 0 to 2.
Engineer’s hammer: Sargent & Co. list engineer’s hammers with a riveting pein and with a ball pein, the ball-pein example weighing 2 lb.
Dead blow ball-peen hammer: Snap-on’s 2005 HBBD series has a steel canister of free-flowing shot inside the head, a polished steel peen and head, and weights of 8 to 40 oz.
Soft-handled steel hammer: Estwing makes ball-peen hammers of 8, 12, 16, 24 and 32 oz with a molded Shock Reduction Grip over a forged steel handle.

Specifications

Head weight · oz: Leonard gives 6 to 28 oz for machine-shop use; Estwing lists 8, 12, 16, 24 and 32 oz; Snap-on’s dead blow series runs 8 to 40 oz.
Handle length · in: Kaup says the handle of a chipping hammer should be 12 to 14 or 15 inches.
Face diameter relative to struck tool · in or mm: Estwing recommends a face at least 3/8 in. larger than the struck tool; CCOHS recommends about 12 mm (0.5 in.) larger.

Made to

ASME B107.400
OSHA 29-CFR-1926-301

Safety and care

Safety

Do not strike a ball-peen hammer against another hammer, another tool or a hardened object. Estwing warns of possible eye or other bodily injury from chipped tools, and CCOHS warns of serious injury from a chipped face.
Wear safety goggles; Estwing says bystanders should also wear them.
Impact tools struck with the hammer, such as drift pins, wedges and chisels, must be kept free of mushroomed heads (OSHA 29 CFR 1926.301(c)).
CCOHS says not to redress, grind, weld or reheat-treat a hammer head.

Care

Discard the hammer if the face is chipped or dented or has mushroomed, or if the handle is dented (Estwing).
Replace a wooden handle that is cracked, splintered or loose in the head (CCOHS; OSHA 29 CFR 1926.301(d) requires wooden handles to be kept tight and free of cracks).
Wipe off grease and moisture and store the hammer in a clean, dry place (Estwing).

Tips

Support the far end of the rivet while peening
Leonard describes cold riveting in the machine shop: the pin is set in place and the end is hammered down to fill the countersink, while the other end is held against an anvil or another suitable support.1
Choose the weight by the work
Leonard gives 6 to 16 oz hammers for light riveting and layout, and the heavy sizes for heavy riveting, chipping and general shop work. Kaup says a 1 lb hammer does more effective and better all-around chipping than a heavier one.1 2
Keep the face larger than the struck tool
When striking a punch or chisel, the hammer face should overlap the struck face. Estwing gives at least 3/8 in. larger and CCOHS gives about 12 mm larger, so that the edge of the face does not land on the edge of the struck tool.1 2
Check how the handle sits in the eye
Leonard says the long diameter of the handle should lie in the plane through the axis of the hammer, so the hand need not twist to bring the face down square. The handle may incline slightly toward the head and should never incline the other way.1
Grip near the end and strike one blow at a time
Leonard advises holding the handle near the end, and at the extreme end for the heaviest work, and swinging in a plane only slightly inclined from the vertical. He also warns against the habit of striking a heavy blow followed by a light one.1
Do not use the hammer on hardened steel
Estwing assigns the ball-peen hammer to riveting, shaping and straightening unhardened metals and to striking punches and chisels. A drilling hammer is the tool Estwing names for striking chisels, punches, star drills and hardened nails.1 2

History

Earliest documented

1869

New York, United States (catalog of Sargent & Co.)

The earliest dated listing located is in Sargent & Co.’s 1869 catalog, which prices Maydole’s cast steel machinist’s ball-pein hammers in sizes 0 to 7, from $20.00 down to $7.50 a dozen, besides engineer’s hammers with a riveting pein and a ball pein. Handled hammers for riveting are older than the catalog; Petrie describes the medieval smith’s hammer as having a heavy square head with a wide edge for riveting, and Moxon describes a small riveting hammer in the smithing trade in the 1600s. No earlier dated use of the name ball pein has been located.1 2 3

The ball-peen hammer belongs to the family of metalworking hammers whose job is to move metal. Petrie’s survey of ancient tools finds that handled hammers for metal came late. The Egyptians used a smooth stone in the hand even for beating out copper vessels. A handled bronze hammer appears in Europe only shortly before iron became general, and the larger smith’s hammer does not appear until Roman times. Petrie’s medieval and later smith’s hammer has a heavy square head with a wide edge for riveting and detailed work.

By the later seventeenth century the trade had separate hammers by size. Moxon names a hand hammer, an up-hand sledge and an about sledge, and a fourth, the riveting hammer, which he calls the smallest of all and rarely used at the forge. He says it is used on cold iron for riveting and for setting or crooking small work. This is the work the ball peen later did in the machine shop, though Moxon’s text does not use the name.

The name and the machinist’s hammer appear together in the nineteenth century. Sargent & Co. offered the machinist’s ball-pein hammer in eight numbered sizes in 1869, and Knight’s dictionary defines it in a single line. By the first years of the twentieth century machine-shop texts treated it as one of three ordinary forms, distinguished only by the shape of the peen. Leonard and Kaup both give the peen the task of riveting and describe a crowned, hardened face.

Present practice divides the hammer’s two ends between two kinds of work, and the sources do not agree on how far the face may be used on other tools. Estwing’s catalog says the flat face is used for striking punches and chisels and the ball for shaping unhardened metal. Its safety page assigns the ball peen to riveting, shaping and straightening unhardened metals, and the drilling hammer to chisels, punches and hardened nails. Both agree with CCOHS that a hammer must never be struck against another hammer or a hardened object.

The form has remained stable while its materials changed. Estwing makes it with a forged steel handle and molded grip in five sizes up to 32 oz; Snap-on in 2005 added a shot-filled dead blow version. In the O*NET Tools Used table the ball-peen hammer commodity class covers 31 occupations.

Timeline

Roman period
The larger smith’s hammer appears in Roman times, according to Petrie, after the Greek iron hammer, which was small and light. Petrie says the Egyptians never made a handled hammer for metal and used a smooth stone held in the hand.1
1677 onward
Moxon describes the riveting hammer in his smithing numbers as the smallest hammer of the trade, rarely used at the forge and used on cold iron for riveting and for setting or bending small work straight.1
1869
Sargent & Co. of New York list Maydole’s machinist’s ball-pein hammers in sizes 0 to 7, with machinist’s chipping hammers and engineer’s hammers, in their hardware catalog.1
1870s
Knight’s American Mechanical Dictionary defines the ball-peen hammer as a metal-worker’s hammer with a spherical peen.1
1906–1908
Leonard’s Machine-Shop Tools and Methods describes the three forms of machinist’s hammer, the tempering of both ends with the eye left soft, and the use of the peen for riveting and stretching.1
1914
Kaup’s Machine Shop Practice describes the straight-peen, cross-peen and ball-peen hammers and recommends a 1 lb hammer for all-around chipping.1
1915
Googerty’s school forging text calls for two ball hammers at each anvil, the heavier about 2 lb, and for a ten-pound sledge hammer for every two forges.1
2005
Snap-on announces a ball-peen dead blow hammer series with a steel canister of free-flowing shot in the head, in sizes of 8 to 40 oz.1
2008
ASME B107.400-2008 folds the earlier ball-peen hammer standard, ASME B107.53, into a single striking tools standard, with B107.41 on nail hammers and B107.54 on heavy striking tools.1

Where the sources disagree

How much larger than the struck tool should the hammer face be?

At least 3/8 in. (about 9.5 mm) larger than the face of the struck tool.1 2
Estwing Manufacturing Company
About 12 mm (0.5 in.) larger than the face of the tool being struck.1
Canadian Centre for Occupational Health and Safety

Gaps in the record (6)

The origin of the word peen and the date at which ball pein first appears in print have not been located; the earliest dated use read here is the 1869 catalog.
The Knight’s dictionary copy read is a 1876 printing; the first edition is reported to be 1874 and was not read.
No museum record of a dated ball-peen hammer head has been located.
The Sargent catalog text is a poor scan: head weights of the numbered ball-pein sizes could not be read, so they are not stated.
ASME B107.400 text was not read; only the table of contents of the 2008 edition. The standard slugs are unverified.
No published test or failure data has been located to judge handle materials or head designs, so buying is null.