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A punch is a
tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many animals use simple tools, only human beings, whose use of stone tools dates ba ...
used to indent or create a hole through a hard surface. They usually consist of a hard
metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...
rod with a narrow tip at one end and a broad flat "butt" at the other. When used, the narrower end is pointed against a target surface and the broad end is then struck with a hammer or mallet, causing the blunt force of the blow to be transmitted down the rod body and focused more sharply onto a small area. Typically,
woodworker Woodworking is the skill of making items from wood, and includes cabinet making (cabinetry and furniture), wood carving, joinery, carpentry, and woodturning. History Along with stone, clay and animal parts, wood was one of the first materials ...
s use a ball-peen hammer to strike a punch.


Use

Punches are used to drive
fastener A fastener (US English) or fastening (UK English) is a hardware device that mechanically joins or affixes two or more objects together. In general, fasteners are used to create non-permanent joints; that is, joints that can be removed or disman ...
s such as
nail Nail or Nails may refer to: In biology * Nail (anatomy), toughened protective protein-keratin (known as alpha-keratin, also found in hair) at the end of an animal digit, such as fingernail * Nail (beak), a plate of hard horny tissue at the tip ...
s and dowels, making a
hole A hole is an opening in or through a particular medium, usually a solid body. Holes occur through natural and artificial processes, and may be useful for various purposes, or may represent a problem needing to be addressed in many fields of en ...
, or forming an indentation/impression of the tip on a workpiece. Decorative punches may also be used to create a pattern or even form an image.


Pin

Metal pins and similar connectors are driven in or out of holes using a pin punch. For removal, first use a starter punch to loosen the pin, then use a pin punch to finish.


Center

A ''center punch'' is used to mark the center of a point. It is usually used to mark the center of a hole when drilling holes. A drill has the tendency to "wander" if it does not start in a recess. A center punch forms a large enough dimple to "guide" the tip of the drill. The tip of a center punch has an angle between 60 and 90 degrees. When drilling larger holes, where the drill bit is wider than the indentation produced by a center punch, the drilling of a
pilot hole In construction, a pilot hole is a small hole drilled into a piece of construction material. Its purpose may be: #to guide a larger drill to the appropriate location and ease the job of the larger drill #allow for the insertion of another hole-m ...
is usually needed. An automatic center punch operates without the need for a hammer.


Prick punch

A ''prick punch'' is similar to a center punch but used for
marking out Marking out or layout means the process of transferring a design or pattern to a workpiece, as the first step in the manufacturing process. It is performed in many industries or hobbies although in the repetition industries the machine's initial set ...
. It has a sharper angled tip to produce a narrower and deeper indentation. The indentation can then be enlarged with a center punch for drilling. The tip of a prick punch is 60 degrees (the angle depends on what type of prick punch one is using). It is also known as a dot punch.


Transfer

A ''transfer punch'' is a punch (usually in an
index set In mathematics, an index set is a set whose members label (or index) members of another set. For instance, if the elements of a set may be ''indexed'' or ''labeled'' by means of the elements of a set , then is an index set. The indexing consists ...
) of a specific outer diameter that is non-tapered and extends the entire length of the punch (except for the tip). It is used to tightly fit the tolerances of an existing hole and, when struck, precisely ''transfer'' the center of that hole to another surface. It can be used, for example, to duplicate the hole patterns in a part, or precisely set locations for threaded holes (created by drilling and
tapping Tapping is a playing technique that can be used on any stringed instrument, but which is most commonly used on guitar. The technique involves a string being fretted and set into vibration as part of a single motion. This is in contrast to stand ...
) to bolt an object to a surface.


Drift

A ''drift "punch"'' is misleadingly named; it is not used as a punch in the traditional sense of the term. A drift punch, or drift pin, or lineup punch, is used as an aid in aligning bolt or
rivet A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite to the head is called the ''tail''. On installation, the rivet is placed in a punched ...
holes prior to inserting a fastener. A drift punch is constructed as a tapered rod, with the hammer acting on the large end of the taper. The long end of a drift punch is placed into the semi-aligned bolt holes of two separate components, and then driven into the hole. As it is driven in, the taper forces the two components into alignment, allowing for easy insertion of the fastener. Unlike most punches, force is never (and should never be) applied to the tip, or end of a drift pin.


Spring or roll pins

Spring punches, also called roll pin punches, are used to drive roll pins. Standard pin punches should never be used on a roll pin. Because of the hollow, thin wall construction of a roll pin, a standard pin punch will often collapse, mar or distort the end of the pin or be driven into, and jammed inside, the hollow core of the roll pin. When choosing a roll pin punch, select one that is no larger than the compressed diameter of the pin. If a punch is used that is larger than the pin, the surrounding metal in which the pin is seated can be damaged. Also, a roll pin punch should not be used which is smaller than the compressed diameter of the pin. If this occurs, it may be possible to drive the punch through the hollow center of the roll pin. Roll pin punches are designed with a small projection in the center of the pin tip to support the circumference of the roll pin. The tips of roll pin punches are not flat and should never be used on regular solid pins. If a roll pin punch is used on a solid pin, it will mar or mark the pin. If the end of a roll pin punch is damaged or deformed, it should be discarded. It is virtually impossible to regrind the tip of the roll pin punch and properly shape the center projection. When using a roll pin punch, make sure the axis of the shank of the roll pin punch is in line with the axis of the roll pin. Do not cant the roll pin punch off to one side. When you strike the roll pin punch, hit it directly on the top of its head. If you strike the head of the roll pin punch at an angle you may bend the shank.


Decorative

Punches with a decorative motif have been used to create patterns or images on metals and various other materials, notably
leather Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hog ...
. In
goldsmith A goldsmith is a metalworker who specializes in working with gold and other precious metals. Nowadays they mainly specialize in jewelry-making but historically, goldsmiths have also made silverware, platters, goblets, decorative and servicea ...
ing, bookbinding and
armor Armour (British English) or armor (American English; see spelling differences) is a covering used to protect an object, individual, or vehicle from physical injury or damage, especially direct contact weapons or projectiles during combat, or f ...
-making the technique is called pointillé. In printmaking punches were used to create most of the image in the plates for printing
metalcut Metalcut was a relief printmaking technique, belonging to the category of old master prints. It was almost entirely restricted to the period from about 1450 to 1540, and mostly to the region around the Rhine in Northern Europe, the Low Countries, ...
s.


Letter

Also known as ''letter stamps'' or ''number stamps'', letter punches are used to emboss the impression of a letter or number into a workpiece. They are most common in the reverse image, this allows the end result to be immediately readable, regardless they may be made as a positive image. This is essential in the case of die or mold making and ensures that the finished product will be readable, as a die is a negative image.


Tablet press

These punches are a part of
tablet press A tablet press is a mechanical device that compresses powder into tablets of uniform size and weight. A tablet press can be used to manufacture tablets of a wide variety of materials, including pharmaceuticals, nutraceuticals, cleaning products, ...
. Unlike most punches, tablet press punches have a concave ending in the shape of the desired tablet. There are the lower and the upper punches to compress the powder in between.


See also

* Automatic center punch * Nailset *
Punchcutting Punchcutting is a craft used in traditional typography to cut letter punches in steel as the first stage of making metal type. Steel punches in the shape of the letter would be used to stamp matrices into copper, which were locked into a mould s ...
*
Punching Punching is a forming process that uses a punch press to force a tool, called a ''punch'', through the workpiece to create a hole via shearing. Punching is applicable to a wide variety of materials that come in sheet form, including sheet meta ...
*
Punching machine A punching machine is a machine tool for punching and embossing flat sheet-materials to produce form-features needed as mechanical element and/or to extend static stability of a sheet section. CNC punching Punch presses are developed for high ...


References

{{DEFAULTSORT:Punch (Tool) Hand tools Metalworking hand tools Woodworking hand tools