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Shot tower

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Shot tower, Tasmania (1870)
Clifton Hill Shot Tower, Melbourne
The Shot Tower, Bristol, England
Coops (Melbourne Central) Shot Tower, encased by the Melbourne Central cone
The Dubuque, Iowa shot tower

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

Shot making

Process

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, then solidifies as it falls. The partially cooled balls are caught at the floor of the tower in a water-filled basin.[1] 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.[2] To make larger shot sizes, a copper sieve with larger holes is used. However, the maximum size is limited by the height of the tower, because larger shot sizes must fall farther to cool. 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).[3] A polishing with a slight amount of graphite is necessary for lubrication and to prevent oxidation.

History

The process was invented by William Watts of Bristol, UK, and patented in 1782.[1][4] The same year, Watts extended his house in Redcliffe, Bristol to build the first shot tower.[5] Shot towers replaced the earlier techniques of casting shot in moulds, which was expensive, or of dripping molten lead into water barrels, which produced insufficiently spherical balls. Large shot which could not be made by the shot tower were made by tumbling pieces of cut lead sheet in a barrel until round.[6]

The "wind tower" method, patented in 1848 by the T.O LeRoy Company of New York City, which used a blast of cold air to dramatically shorten the drop necessary[7][8] 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 is 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.[9]

Examples

Steel-framed 1916 Colonial Ammunition Company tower in Auckland, New Zealand
Name Location Country Year Notes
Berlin Shot Ball Tower Berlin Rummelsburg Germany 1908 Nöldnerstraße 15 and 16. Used until 1939
Brussels Shot Tower Brussels Belgium ?
Cheese Lane Shot Tower Bristol, England United Kingdom 1969 A reinforced concrete tower built to replace the very first shot tower built in Redcliffe by William Watts[10]
Chester Shot Tower Boughton, England United Kingdom 1799 A circular brick tower; the oldest surviving shot tower in the UK[11]
Clifton Hill Shot Tower Melbourne, Victoria Australia 1882 A brick structure that is 80.1 m (263 ft) high.[12] And the tallest remaining in Australia[13]
Colonial Ammunition Company Mt Eden, Auckland New Zealand 1916 A steel framed tower[14]
Coop's Shot Tower Melbourne, Victoria Australia 1888 50 meters (160 ft) high[15]
Daugavpils Shot Factory Tower Daugavpils Latvia ? Still in operation[16][17]
Drochtersen Shot Tower Drochtersen, Lower Saxony Germany ?
Dubuque Shot Tower Dubuque, Iowa United States 1856
Fort Hayes Shot Tower Columbus, Ohio United States 1864 Currently in use with the Fort Hayes Metropolitan Education Center
Helena Shot Tower Spring Green, Wisconsin United States 1831 Preserved as part of a state park[18]
Jackson Ferry Shot Tower Wythe County, Virginia United States 1790s Now part of a state park and open to the public during the tourist season.[19]
Lambeth Shot Tower London, England United Kingdom 1826 In use until 1949, and was a feature in the 1951 Festival of Britain, before being demolished.
McCullough Tower Lower Manhattan, New York United States 1855-6 The first shot tower constructed of an iron frame rather than masonry. Built by James Bogardus with a height of 175 ft (53 m). Demolished 1907.[20]
New Vienna Shot Tower New Vienna, Iowa United States ? [citation needed]
Peters Shot Tower Kings Mills, Ohio United States 1895
Pispala Shot Tower Pispala, Tampere Finland 1908 Height 55 m (180 ft). Used until 1972. [citation needed]
Phoenix Shot Tower Baltimore, Maryland United States 1828
Redcliffe Shot Tower Bristol, England United Kingdom 1782 The first shot tower, built by William Watts, the inventor of the tower process for the manufacture of lead shot. Demolished in 1968.[10]
Remington Shot Tower Lonoke, Arkansas United States 1969 Moved from Bridgeport, Connecticut[21].
Rossie Shot Tower Rossie, New York United States ? [citation needed]
Sparks Shot Tower Philadelphia, Pennsylvania United States 1808 In use until 1913. Now part of a children's playground
Stelco Shot Tower Montreal, Quebec Canada ? [22]
Tapham Tower Lower Manhattan, New York United States 1855-6 Built by James Bogardus with a height of 217 ft (66 m). Demolished in the first decade of the 20th century.[citation needed]
Taroona Shot Tower Hobart, Tasmania Australia 1870
Winchester Shot Tower New Haven, Connecticut United States ? [citation needed]

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 drop in a tower.

Further reading

  • "Up a shot tower". The Strand Magazine. 1891. p. 205.

References

  1. ^ a b "No. 422: Shot Tower", Engines, UH.
  2. ^ Re: How the small lead shot (7–8 sizes) used for shotgun shells are made?, Mad sci, May 2001.
  3. ^ The Physics of Shot Towers (PDF)
  4. ^ Minchinton, Walter (1993). "The Shot Tower" (PDF). The Shot Peener. 7 (3): 22.
  5. ^ "Sheldon Bush and Patent Shot Company Limited, Cheese Lane, Bristol", Images of England.
  6. ^ "150th", The Age, Melbourne, AU, archived from the original on 2006-02-12 {{citation}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help).
  7. ^ [1], Lynne Belluscio, LeRoy Penny Saver News
  8. ^ History of the American Shot Tower Archived August 11, 2005, at the Wayback Machine
  9. ^ "The romance of lead shot - Shotgunner – Guns Magazine – Find Articles at BNET.com". Archived from the original on 2006-05-05. {{cite news}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  10. ^ a b Efstathios, Tsolis (2007-03-10). "An Awkward thing" (PDF). University of Bristol. Retrieved 2015-03-19.
  11. ^ "Chester Leadworks and Shot Tower", Images of England.
  12. ^ Heritage, Victoria, AU.
  13. ^ "Melbourne Central - Our Heritage". www.melbournecentral.com.au. Retrieved 2017-02-15.
  14. ^ "Colonial Ammunition Company Shot Tower". New Zealand Heritage List/Rārangi Kōrero. Heritage New Zealand. Retrieved 2010-03-02.
  15. ^ "Victorian heritage directory". vhd.heritagecouncil.vic.gov.au. Retrieved 2017-02-15.
  16. ^ DSR, LV.
  17. ^ "Daugavpils Lead Shot Factory". Official Latvian Tourism Portal. Latvian Tourism Development Agency. 12 June 2013. Retrieved 12 September 2013.
  18. ^ Tower Hill State Park Shot Tower, WI, US.
  19. ^ Shot Tower Historical State Park, VA, US
  20. ^ Gayle, Margot; Gayle, Carol (1998). Cast-iron Architecture in America: The Significance of James Bogardus. W. W. Norton & Company. pp. 169–174. ISBN 0393730158.
  21. ^ "Remington Ammunition & Components Plant - Lonoke, AR". Waymarking.com. Retrieved 5 July 2017.
  22. ^ http://www.waymarking.com/waymarks/WMDXNA_Montreal_Shot_Tower_Montreal_Qc_Canada
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