Needlegun scaler

A U.S. Navy Seaman uses a needle-gun to remove old paint and corrosion aboard USS Kitty Hawk.[1]

A needlegun scaler, needle scaler or needle-gun is a tool used to remove rust, mill scale, and old paint from metal surfaces.[2] The tool is used in metalwork applications as diverse as home repair, automotive repair and shipboard preservation.[3][4][5]

Operation and use

A needle gun has a set of very fine chisels known as needles.[3] The tool forces these needles against a work surface at variable speeds up to around 5,000 times per minute.[3][2] Different models offer choices of number of needles, operating speed, and power levels.[3] Many models use compressed air, although electrical needle-guns do exist.[3][6]

In a pneumatic unit, compressed air forces a piston forwards and backwards.[3] This movement causes the needles to move back and forth against the work surface.[3]

An able seaman uses a needlegun to remove scale while refurbishing a mooring winch.

The needle gun has advantages over other scaling tools. Its main advantage is that the needles automatically adjust themselves to contours, making the tool a good choice for cleaning irregular surfaces.[2] A needle gun can clean an area to bare metal in seconds, and compares well to other scaling tools in terms of accuracy and precision.[3]

It is recommended that before needlegunning, a surface should be prepared by removing oil, grease, dirt, chemicals and water-soluble contaminants.[5] This can be done with solvents or with a combination of detergent and fresh water.[5] Then, the needle gun is used to remove rust, loose scale, and paint, leaving bare metal.[5] It is used most effectively by holding it at a 45° angle to the work surface.[5] It is recommended that an area no larger than six to eight inches be cleared at once.[5] Two to three passes over an area is generally sufficient to clean it.[5] Then the process is repeated until the desired area is completed.[5]

Prior to painting, it is desirable to feather any edges between metal and old paint.[5] It is also important to check the surface for oil deposited during chipping, and if necessary, clean the area with solvents.[5] Since bare metal surfaces will flash rust soon after exposure to the atmosphere, paint should be applied as soon as possible after chipping.[5] If flash rusting occurs prior to coating, further chipping, cleaning and sanding may be necessary.[5]

See also


  1. U.S. Navy, 2006.
  2. 1 2 3 NETC, 2003, p. 11-10.
  3. 1 2 3 4 5 6 7 8 Miller, 2008.
  4. Park, 1984.
  5. 1 2 3 4 5 6 7 8 9 10 11 12 NAVSEA, 2008.
  6. Nitto Kohki, 2008.



External links

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