The GUIDE to NUTS and Bolts
NUT TYPES - Quick guide to the different designs
These are steel nuts with a nylon insert added into a shoulder piece. This insert is an interference fit on the thread over which it is fitted, and therefore provides a friction locking action; Generally taller than an ordinary Hex nut, they are often used with plain washers, and should be used only once, as each subsequent use will diminish the locking action; Good in areas where vibration is prevalent, but not where heat is expected.
Box of 300 pieces - UNF, UNC and Metric boxes
Used where extreme heat is present, such as on exhaust manifolds. The brass nuts expands more than steel when hot, and can be more easily undone if heat is applied. These are often tall to compensate for their softness.
SCREW TYPES - Specific applications, threads and features
These are fully threaded screws and are screwed into drilled sheet metal or into U-nuts.
WASHER TYPES - These are the chaps that lessen your load
Penny washers are used where a load needs to be distributed over a larger area, often when being used on thin or fragile applications, such as attachements to body panels and other pressed-steel components.Box of 240 pieces
This type of washer is used to prevent nuts or bolts loosening, especially where vibration may be present. They can be used in conjunction with flat washer types as the spring force wil still be exerted, but are at their best on their own.Box of 1000 pieces
Internal Tooth Lock Washers
A washer with internal teeth twisted in an anti-clockwise direction to provide a spring and frictional means of preventing nuts and bolts from undoing. They are not as robust as ordinary spring washers.
Box of 1000 pieces (Metric or Imperial)
Spire Clip (U Clip)
Used in conjunction with self-tapping screws, spire clips are often found on thin, pressed metal components, or holding decorative items.
Many of us have experienced the sickening moment when a bolt is over-tightened in a casting, and the thread strips; Helicoils are oversized external threads with a correct size (for the application) internal thread. The stripped thread is drilled out to accept the next size tap, and a new thread is cut, into which is fitted the helicoil.
Split-pins are a mechanical locking device used with castellated nuts and in othersituations. Once used, they should never be re-used, as they will be suffering from metal fatigue. Not to be confused with cotter pins, which is a solid pin found holding a kingpin in place.
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