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

Operation and use

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

In a pneumatic unit, compressed air forces a piston forwards and backwards.^[2] This movement causes the needles to move back and forth against the work surface.^[2]

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.^[5] 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.^[2]

It is recommended that before needlegunning, a surface be prepared by removing oil, grease, dirt, chemicals and water-soluble contaminants.^[4] This can be done with solvents or with a combination of detergent and fresh water.^[4]

Then, the needle gun is used to remove rust, loose scale, and paint, leaving bare metal.^[4] It is used most effectively by holding it at a 90° angle to the work surface.^[4] It is recommended that an area no larger than six to eight inches be cleared at once.^[4] Two to three passes over an area is generally sufficient to clean it.^[4] Then the process is repeated until the desired area is completed.^[4]

Prior to painting, it is desirable to feather any edges between metal and old paint.^[4] It is also important to check the surface for oil deposited during chipping, and if necessary, clean the area with solvents.^[4] Since bare metal surfaces will flash rust soon after exposure to the atmosphere, paint should be applied as soon as possible after chipping.^[4] If flash rusting occurs prior to coating, further chipping, cleaning and sanding may be necessary.^[4]

See also

Nautical portal

• Abrasive blasting
• Corrosion
• Wire brush

Notes

1. ^ U.S. Navy, 2006.
2. ^ ^{a b c d e f g h} Miller, 2008.
3. ^ Park, 1984.
4. ^ ^{a b c d e f g h i j k l} NAVSEA, 2008.
5. ^ ^{a b c} NETC, 2003, p. 11-10.
6. ^ Nitto Kohki, 2008.

References

• Miller, Jason (2008-01-30). "Needle Scaler and Debris Removal". Free Online Library. Free Online Library. http://www.thefreelibrary.com/Needle+Scaler+and+Debris+Removal-a01073853851. Retrieved 2008-04-05. 
• Naval Sea Systems Command (NAVSEA) (2008). "Chapter 7: Submarine Forces Afloat Painting and Preservation Guidelines for Non-Nuclear Spaces and Components". Contracted Ship Maintenance. Joint Fleet Maintenance Manual - Rev A Change 7. VI. United States Navy. http://www.submepp.navy.mil/jfmm/HTML/Volume%20VI/VI-Ch-07.htm. 
• Naval Education and Training Command (NETC) (2003) [1996]. "Chapter 11: Painting". NAVEDTRA 14343: Boatswain's Mate. Nonresident Training Manuals. Pensacola, Florida: United States Navy. http://www.navystorekeeper.com/NAVEDTRA_14343.pdf. Retrieved 2008-04-05. 
• Park, Sharon (1984). "#13: The Repair and Thermal Upgrading of Historic Steel Windows". Preservation Briefs. Government Publishing Office. http://w3.gsa.gov/web/p/HPTP.NSF/a533f1f859737bc9852565cc0058d0b6/064f66fe515200ca852565c50054b2ff?OpenDocument. Retrieved 2008-04-05. 
• Nitto Kohki (2008). "EJC-32A Electric Needle Scaler". nittokohki.com. Nitto Kohki USA. http://www.nittokohki.com/tools/products/powertools/needlescalers/ejc-32a.html. Retrieved 2008-04-05. 
• U.S. Navy (2006-03-23). "Eye on the Fleet". Navy NewsStand. United States Navy. http://www.navy.mil/view_single.asp?id=33020. Retrieved 2008-04-05. 

External links

• Video of needle-gunning rust
• Battleship Texas Restoration Manual
• Safety while removing paint
• Schematic and parts list for Jet Chisel JT-20