Punch (tool)

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For punches used in punch presses, see Punching.

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Engraving punch

A punch is a hard metal rod with a sharp tip at one end and a blunt butt end at the other, which is usually struck by a hammer. Typically, woodworkers use a ball-peen hammer to strike a punch.

UseEdit

Punches are used to drive objects such as nails, or to form an impression of the tip on a workpiece. Decorative punches may also be used to create a pattern or even form an image.[citation needed]

PinEdit

Pin punch

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.

CenterEdit

Centre punch

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.[1] When drilling larger holes, and the web, that is the center of the drill tip, is wider than the indentation produced by a center punch, the drilling of a pilot hole is usually needed.

An automatic center punch operates without the need for a hammer.

Prick punchEdit

Prick punch

A prick punch is similar to a center punch but used for marking out. 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 40 degrees (the angle depends on what type of prick punch one is using).[1] It is also known as a dot punch.

TransferEdit

Transfer punch

A transfer punch is a punch (usually in an index set) 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) to bolt an object to a surface.

DriftEdit

Drift punch

Main article: Drift pin

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 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 tapered 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.