# Knockout punch > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Knockout_punch > Markdown URL: https://mediated.wiki/source/Knockout_punch.md > Source: https://en.wikipedia.org/wiki/Knockout_punch > Source revision: 1310707447 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|Hand tool for punching holes through sheet metal}} {{For|the winning criteria of a striking sport|Knockout}} thumb|Chassis punches: assorted sizes round and square thumb|Chassis punches: assorted sizes round and square disassembled In [metalworking](/source/metalworking), a '''knockout punch''', also known as a '''chassis punch''', '''panel punch''', '''Greenlee punch''', or a '''Q-max''',{{Citation | last = Benchmark Media UK | title = Producing Sheet Metal Components and Assemblies | page = 50 | publisher = Benchmark Media Limited | url = https://books.google.com/books?id=KoaoG08u2YIC&pg=PA50 | postscript =.}} is a [hand tool](/source/hand_tool) used to [punch](/source/punching) a hole through [sheet metal](/source/sheet_metal). It is a very simple tool that consists of a punch, [die](/source/die_(manufacturing)), and [screw](/source/screw). There are three different drive systems: manual, [ratchet](/source/Socket_wrench), and [hydraulic](/source/hydraulic).{{Citation | last = Fournier | first = Sue | title = Metal fabricator's handbook | page = 16 | publisher = HPBooks | year = 1990 | url = https://books.google.com/books?id=qCmoaBtYjYkC&pg=PA16 | isbn = 978-0-89586-870-1 | postscript =.}} ==Operation== First a [pilot hole](/source/pilot_hole) is drilled slightly larger than the screw of the knockout punch. Then the die is placed on the screw and the screw is inserted into the pilot hole. The screw is then threaded into the punch and the screw tightened until the punch is drawn completely through the sheet metal. The manual system uses a screw that has a standard [hex head](/source/hex_head) or square head and is driven using an allen key or [wrench](/source/wrench). A manual knockout punch can handle holes from {{convert|0.5|to|1.25|in|abbr=on}}. The ratchet system has a custom ratcheting wrench that uses a [ball screw](/source/ball_screw) to make the process faster and easier. This type of system has a [mechanical advantage](/source/mechanical_advantage) of approximately 220:1 and can punch holes up to {{convert|3|in|abbr=on}} in diameter in 10 gauge [mild steel](/source/mild_steel).{{Citation | last = Miller | first = Rex | title = Electrician's Pocket Manual | pages = 43–44 | publisher = McGraw-Hill Professional | year = 2000 | url = https://books.google.com/books?id=NUcKsr4YAj0C&pg=PA43 | isbn = 978-0-07-136026-5 | postscript =.}} A hydraulic system is much bulkier and heavier than the other systems but it is the easiest to use and can make holes up to {{convert|6|in|abbr=on}} in diameter. It is a two-piece system where the dies are attached to the ram which is connected to the hydraulic unit via a flexible hose.{{Citation | last = Tuck | first = David | title = Electrician's Instant Answers | page = 240 | publisher = McGraw-Hill Professional | year = 2003 | url = https://books.google.com/books?id=jgT8cfRmsl4C&pg=PA240 | isbn = 978-0-07-140203-3 | postscript =.}}{{Citation | last = Fletcher | first = Gregory W. | title = Residential Construction Academy House Wiring | page = 70 | publisher = Cengage Learning | year = 2003 | url = https://books.google.com/books?id=xGtcfPzGWckC&pg=PA70 | isbn = 978-1-4018-1371-0 | postscript =.}}{{Citation | title = Knockout punch | journal = [Popular Mechanics](/source/Popular_Mechanics) | volume = 94 | issue = 3 | page = 139 | date = September 1950 | url = https://books.google.com/books?id=mdgDAAAAMBAJ&pg=PA139 |issn=0032-4558 | postscript =.}} ==Size families and shapes== There are several sizing systems for these punches. The two most common are those sized for standard electrical knockout sizes and those that are for true dimensional holes. A 3/4 inch [conduit](/source/Electrical_conduit) size punch actually punches a hole that is approximately 1.1 inches diameter for 3/4 nominal size conduit. A dimensional size punch makes a hole very close to the indicated size. Punch sets are available on both imperial and metric sizes. Chassis punches are available in a number of shapes, round being the most common. Other shapes include square, hexagonal, and special shapes for thing such as holes with key tabs and [D-sub connector](/source/D-sub_connector)s{{Citation|title=Greenlee panel punches |url=http://www.greenlee.com/catalog/Knockouts |url-status=dead |archiveurl=https://web.archive.org/web/20140508030152/http://www.greenlee.com/catalog/Knockouts |archivedate=2014-05-08 }} Special shapes often use bolts that are square or keyed and a separate nut on the punch end to ensure alignment of the punch and die. {{Portal|Manufacturing}} ==References== {{reflist}} Category:Metalworking hand tools --- Adapted from the Wikipedia article [Knockout punch](https://en.wikipedia.org/wiki/Knockout_punch) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Knockout_punch?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.