{{Short description|Tower used for the production of lead balls}} {{Use mdy dates|date=January 2022}} [[File:DubuqueShotTowerMay04.jpg|thumb|upright|The shot tower in Dubuque, Iowa]]

A '''shot tower''' is a tower designed for the production of small-diameter shot balls by free fall of molten lead, which is then caught in a water basin. The shot is mainly used for projectiles in shotguns, and for ballast, radiation shielding, and other applications for which small lead balls are useful.

== Shot making ==

=== Process === thumb|upright=0.3|How a shot tower works thumb|Lead-alloy musket ball thought from its lack of casting marks to have been made in a shot tower In a shot tower, lead is heated until molten, then dropped through a copper sieve high in the tower. The liquid lead forms tiny spherical balls by surface tension, and solidifies as it falls. The partially cooled balls are caught at the floor of the tower in a water-filled basin.<ref name = "uh">{{Citation | url = http://www.uh.edu/engines/epi422.htm | contribution = No. 422: Shot Tower | title = Engines | publisher = UH}}.</ref> The now fully cooled balls are checked for roundness and sorted by size; those that are "out of round" are remelted. A slightly inclined table is used for checking roundness.<ref>{{Citation | url = http://www.madsci.org/posts/archives/may2001/991166342.Eg.r.html | title = Re: How the small lead shot (7–8 sizes) used for shotgun shells are made? |date=May 2001 | publisher = Mad sci}}.</ref> <ref>THE SHOT TOWER. (1932, December 24). The Age (Melbourne, Vic. : 1854 - 1954), p. 7. Retrieved April 22, 2026, from http://nla.gov.au/nla.news-article204296854</ref> To make larger shot sizes, a copper sieve with bigger holes is used.

The maximum size is limited by the height of the tower, because larger shot sizes must fall further to solidify. A shot tower with a 40-meter drop can produce up to #6 shot (nominally 2.4mm in diameter) while an 80-meter drop can produce #2 shot (nominally 3.8mm in diameter).<ref>{{Citation | url = https://www.usna.edu/Users/physics/mungan/_files/documents/Publications/TPT20.pdf | title = The Physics of Shot Towers | bibcode = 2012PhTea..50..218L | last1 = Lipscombe | first1 = Trevor C. | last2 = Mungan | first2 = Carl E. | journal = The Physics Teacher | year = 2012 | volume = 50 | issue = 4 | page = 218 | doi = 10.1119/1.3694072 }}</ref> Polishing with a small amount of graphite is necessary for lubrication and to prevent oxidation.

=== History ===

The process was invented by William Watts of Bristol, England, and patented in 1782.<ref name="uh" /><ref name= Minchinton>{{cite journal|last= Minchinton|first= Walter| title = The Shot Tower | journal =The Shot Peener|year= 1993|volume=7|issue=3|url= http://www.shotpeener.com/library/pdf/1993125.pdf|page = 22}}</ref> The same year, Watts extended his house in Redcliffe to build the first shot tower.<ref name="bristol">{{Citation | url = https://historicengland.org.uk/listing/the-list/list-entry/1059030 | title = Images of England | contribution = Sheldon Bush and Patent Shot Company Limited, Cheese Lane, Bristol}}.</ref> Use of shot towers replaced earlier techniques of casting shot in moulds, which was expensive, or of dripping molten lead into water barrels, that produced insufficiently spherical balls. Large shot which could not be made by the shot tower was made by tumbling pieces of cut lead sheet in a barrel until round.<ref>{{Citation|url=http://150.theage.com.au/view_bestofarticle.asp?straction=update&inttype=1&intid=705 |newspaper=The Age |title=150th |place=Melbourne, AU |url-status=dead |archive-url=https://web.archive.org/web/20060212012158/http://150.theage.com.au/view_bestofarticle.asp?straction=update&inttype=1&intid=705 |archive-date=February 12, 2006 }}.</ref>

The "wind tower" method, which used a blast of cold air to dramatically shorten the drop necessary and was patented in 1848 by the T.O LeRoy Company of New York City,<ref>{{cite web |url=http://www.leroypennysavernews.com/LynneBelluscioArticles/Shot_Towers.htm |title=Shot_Towers |access-date=September 12, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20120130183312/http://www.leroypennysavernews.com/LynneBelluscioArticles/Shot_Towers.htm |archive-date=January 30, 2012 }}, Lynne Belluscio, LeRoy Penny Saver News</ref><ref>[http://www.traphof.org/shot-towers-2/shot-towers-page-1.htm History of the American Shot Tower<!-- Bot generated title -->] {{webarchive |url=https://web.archive.org/web/20050811080101/http://www.traphof.org/shot-towers-2/shot-towers-page-1.htm |date=August 11, 2005 }}</ref> meant that tall shot towers became unnecessary, but many were still constructed into the late 1880s, and two surviving examples date from 1916 and 1969. Since the 1960s, the Bliemeister method has been used to make smaller shot sizes, and larger sizes are made by the cold swaging process of feeding calibrated lengths of wire into hemispherical dies and stamping them into spheres.<ref>{{cite news|url=http://www.findarticles.com/p/articles/mi_m0BQY/is_4_49/ai_98124187 |title=The romance of lead shot |journal= Shotgunner – Guns Magazine |url-status=dead |archive-url=https://web.archive.org/web/20060505081326/http://www.findarticles.com/p/articles/mi_m0BQY/is_4_49/ai_98124187 |archive-date=May 5, 2006 |via=findarticles.com }}</ref>

== Gallery == <gallery> File:Shot-tower SLNSW FL1106006.jpg|Shot-tower, Browns River Road, Tasmania, 1885-90 File:Shot Tower SLNSW FL8635541.jpg|Shot Tower, Wentworth Park, Sydney, by Ashley Cooper, c. 1920 File:Sparks Shot Tower 129-131 Carpenter St Philadelphia PA (DSC 3819).jpg|Sparks Shot Tower, Philadelphia, US (1808) File:Phoenix Shot Tower 02.jpg|Phoenix Shot Tower, Baltimore, US (1828) File:Taroona Shot Tower.jpg|Shot Tower, Taroona, Tasmania, Australia File:Clifton hill shot tower melbourne australia.jpg|Clifton Hill Shot Tower, Melbourne, Australia (1882) File:Tour à plomb Bxl 01.JPG|Brussels Shot Tower, Belgium (1898) File:Colonial Ammunition Company Shot Tower.jpg|Colonial Ammunition Company, Auckland, New Zealand (1914) File:HU-TO-Kölesd11.JPG|Bojárd, Hungary (1936-1938) File:Lookout tower.JPG|Tata, Hungary (1939) File:Cheese Lane Shot Tower after power washing.jpg|Cheese Lane Shot Tower, Bristol, England File:Shottower wytheco.jpg|Jackson Ferry Shot Tower in Wythe County, Virginia, US File:Berlin-Victoriastadt - Schrotkugelturm.jpg|Shot Ball Tower in Berlin, Germany </gallery>

== See also ==

* Drop tube, a similar concept, but used for scientific experiments * Prill, a small granule of material formed by a similar process to shot-making. Often used in the chemical industry for solid chemicals. * Spray drying is a process of turning liquids into powder; many spray dryers also have the drops of liquid solidifying as they fall in a tower.

== References == {{Reflist|35em}}

== Further reading == * {{cite book|title=The Strand Magazine|year=1891|chapter-url=https://archive.org/stream/TheStrandMagazineAnIllustratedMonthly/TheStrandMagazine1891bVol.IiJul-dec#page/n216/mode/1up|page=205|chapter=Up a shot tower}}

== External links == {{Commons category|Shot towers}} * [https://books.google.com/books?id=PyEDAAAAMBAJ&dq=motor+gun+boat&pg=PA123 "Gravity Molds Shot In A Modern Tower", October 1944, Popular Science] detailed and large article on subject of Shot Towers

Category:Shot towers Category:Metalworking Category:Ammunition