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You Might Have a Screw Loose

By Paul Evancoe

Technical Evaluation of the Vibra-Tite VC-3 Threadmate

What is a thread-locking compound, and what is its purpose? Thread-locking compounds are designed to prevent threaded fasteners from becoming loose when exposed to vibration and other counter-torquing forces that cause the screw or nut to back away from its tightened seat. Ultimately, this circumstance results in mechanical failure if thread-locking measures are not taken. This is a common phenomenon seen in all engines/motors, mechanical devices of all purposes and—yes, that’s right—firearms. While thread-locking compounds are employed in firearms for many purposes, the most common is to lock the screws used in rail and scope mounts.

Numerous thread-locking compounds are available online and from gun, automotive and hardware stores. In general, thread-locking compounds are adhesive-based, cure anaerobically and only work on metal threaded surfaces. The majority are formulated for specific ranges of temperature and pressure.

Most thread-locking compounds require the application surfaces to be near perfectly clean in order to achieve adequate surface bonding for proper thread-locking performance. They are additionally formulated for permanent performance where a screw, bolt or nut will likely never need loosening, and for semi-permanent performance where a screw, bolt or nut will probably need to be unfastened for maintenance or loosened for readjustment. In either case, when disassembled, residual thread-locking compound must be entirely removed from the metal surfaces where it was previously applied, prior to any reapplication in the reassembly process. Those of us who have experienced this disassembly, cleaning and reapplication process can affirm that the process is somewhat meticulous and absolutely time-consuming.

Vibra-Tite VC-3 Threadmate, manufactured in the USA by ND Industries, with headquarters in Clawson, MI, entirely resolves the above issues. VC-3 utilizes a special blend of acrylic resins to prevent fasteners from loosening—even under extreme vibration. VC-3 is a powerful locking and sealing coating for threaded fasteners that works on the principle of “friction through viscosity.” Working much like a nylon insert self-locking aircraft nut, VC-3 holds parts in place even during extreme vibration, and it also resists gas and liquid leakage by acting as a seal...

This article first appeared in Small Arms Review V22N5 (May 2018)
and was posted online on March 23, 2018

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