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How to Safety-Wire - Play It Safe!Safety-Wiring Procedures, Methods, And Techniques From the March, 2010 issue of Custom Classic Trucks By Ryan Manson
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It's hard to imagine what the automotive world in general would be like if it weren't for the military-industrial complex. Now, while you may be asking yourself, what has the Navy got to do with my F-100, think about it for a minute. The majority of manufacturing techniques, tools, and materials that were commonplace in the 1950s and '60s, were a direct byproduct of things learned by industry during World War Two. The stringent tolerances demanded by the military and the production challenges that came with them enabled automotive manufacturers to more or less learn on the government's dime in a few short years what would have taken them decades and millions of dollars to develop on their own. Building tanks, ships, and aircraft of all shapes and sizes challenged their manufacturing abilities and allowed them to develop new technologies and techniques that are continued today. Better braking systems, more reliable engines, improved electrical components, precise manufacturing; these were all byproducts of what industry learned while they were manufacturing products for the military. During the late '30s and early '40s, the automotive industry accounted for a major portion of aircraft production, going so far as halting automobile production completely by 1942 to concentrate on aircraft and related production. By the time the war was over, the automobile and related industries would be forever changed. For us truck guys, other than being a neat little bit of history, these military influences have little to do with what we're wrenching on out in the garage. Or so you think. Take the Allen bolt for instance. Invented in the beginning of the 20th century, its name comes from the Allen Manufacturing Company, who actually applied for the patent in 1943 due to escalating needs by the U.S. government brought on by World War Two. And how about all those anodized fittings that you have connecting all your fluid transfer hoses? You know, the ones that take those weird, expensive wrenches that are neither a fractional size nor metric but some seemingly random number preceded by a dash? Known as AN fittings, these mil-spec (military specification) fittings also trace their heritage back to World War Two when the Army and Navy agreed upon a single standard for fluid transfer fittings used to connect flexible hose and rigid metal tubing. This designation became the standard in the aerospace industry for decades and has recently found its way into the classic automobile market. A pair of decent safety wire... A pair of decent safety wire pliers is a must if you're going to be doing it with any regularity. This is the 9-inch pair offered by Graham Tool Co and features reversible action handy for both left- and right-hand twists. The other item necessary is a spool of safety wire. Pictured is a 1lb spool of 0.032-inch military spec stainless steel safety wire. This conforms to the military MS-20995-C and government QQW432 specs. What does that mean? Basically it means that it's the highest quality safety wire available and meets the FAA, military, and the NTSB requirements for use in aircraft. Another aerospace standard that has found its way into the automobile hobby is the practice of "safetying." Familiar to anyone who's ever removed a cotter pin from a ball joint, tie rod, or spindle nut, safetying is defined as securing by various means any nut, bolt, turnbuckle, etc., so that vibration will not cause it to loosen during operation. These practices are not a means of obtaining or maintaining torque, but rather a safety device to prevent the disengagement of hardware. There are three basic methods used in safetying; cotter pins and self-locking nuts, of which are no doubt familiar to most of us, and safety wire. While there may be many of you who are familiar with the practice of safety wire, there is probably a good number who are not. I know I've watched guys do it for years but it's something that I've never seemed to get the hang of. That said, I thought I'd educate myself with help from a few products from Graham Tool Co. and the FAA, and bring you guys along as well. Safetying 101
Basically, there are two methods of safety wiring; the double-twist method that is most commonly used, and the single-wire method used on screws, bolts, and nuts in a closely spaced or closed-geometrical pattern such as a triangle, square, rectangle, or circle. The single-wire method may also be used on parts in electrical systems and in places that are difficult to reach.  A bolt head jig provides a...  A bolt head jig provides a fast, simple way to drill bolt heads with virtually no broken drill bits. Made of 6061 T6 hard anodized aluminum, the jig fits bolt diameters from 3/16- to 5/8-inch and works on hex head, 12-point countersunk, and Allen head cap screws.  To drill the head of the bolt,...  To drill the head of the bolt, a 5/64-inch drill bit is guided by a bushing to ensure that the resulting hole is true.  To drill the threaded portion...  To drill the threaded portion of a fastener, a different drill jig is necessary. Using a 5/64-inch drill bit, fasteners ranging in size from 1/4 to 3/8 inch can be drilled for use with safety wire.  While bolts up to 5/8 inch...  While bolts up to 5/8 inch can be drilled using the bolt...  ...head jig, such as this...  ...head jig, such as this 5/8-inch Allen head bolt larger hardware needs to be drilled using a more universal jig. Here's even another way to... Here's even another way to drill both bolts and nuts. When using the double-twist method, a minimum diameter of 0.032-inch wire should be used on parts that have a hole diameter larger than 0.045 inch. Safety wire of 0.020-inch diameter may be used on parts having a nominal hole diameter between 0.045 and 0.062 inch with a spacing between parts of less than 2 inches. Note that these specs are for steel wire designed for safety wiring and not aluminum, copper, or brass wire. Safety Wiring Procedures
There are many combinations of safety wiring with certain basic rules common to all applications:
1. When bolts, screws, or other parts are closely grouped, it is more convenient to safety wire them in series. The number of fasteners that may be wired together depends on the application. 2. When self-locking nuts are used, their respective bolt heads need not be safety wired. 3. Ensure that the finished safety wire is tight to prevent failure due to rubbing or vibration. 4. Safety wire must be installed in a manner that will prevent the tendency of the part to loosen. 5. Over-stressed safety wire can break under vibration if twisted too tightly. Safety wire must be pulled taut when being twisted and maintain a light tension when secured. 6. Safety wire ends must be bent under and inward toward the part to avoid sharp or projecting ends, which may present a safety hazard. 7. Before safety wiring fasteners, check to see that they are torqued to spec and that the wiring holes are properly aligned to each other. This style can be used when... This style can be used when wiring a single fastener as shown on the lower shock mount. The safety wire is run through the head of the bolt and around the base of the shock, holding it firmly in place.
The safety wire is shown installed for right-hand threaded hardware. For hardware with left-hand threads, the safety wire is routed in the opposite direction. Using Safety Wire Pliers
While safety wiring can be done by hand, it is commonly done using a pair of safety wire pliers. These are similar to traditional pliers, except they feature a center shaft and pull knob that allows the user to hold on to the pliers while they twist the two strands of wire together by pulling on the knob. This ensures a taut fit against the fastener, keeping it from coming loose when wired in conjunction with another fastener or fixed point.  Small screws in closely spaced,...  Small screws in closely spaced, closed geometrical pattern, single-wire method.  Single-fastener application,...  Single-fastener application, double-twist method.  Screwheads, double-twist ...  Screwheads, double-twist method.  External snap ring, single-wire...  External snap ring, single-wire method.  Bolt heads  Castle nuts  Wire twisting by hand.  These four examples apply...  These four examples apply to all bolts, fillister-head screws, square-head plugs, and other similar parts which are wired so that that loosening tendency of either part is counteracted by tightening of the other. The direction of twist from the second to the third unit is counterclockwise in examples one, three, and four to keep the loop in position against the head of the bolt. The direction of twist from the second to the third unit in example two is clockwise to keep the wire in position around the second unit. The wire entering the hole in the third unit will be the lower wire, except in example two, and by making a counterclockwise twist after it leaves the hole, the loop will be secured in place around the head of that fastener.  These four examples show methods...  These four examples show methods for wiring various standard items. Note that the wire may be wrapped over the unit rather than around it when wiring castellated nuts or on other items when there is a clearance problem.  When wiring bolts in different...  When wiring bolts in different planes, the wire should always be applied so that tension is in the tightening direction.  Shown is the correct application...  Shown is the correct application of single wire to closely spaced multiple group fasteners.  Fittings incorporating wire...  Fittings incorporating wire lugs shall be wired as shown.  Hollow-head plugs shall be...  Hollow-head plugs shall be wired as shown with the tab bent inside the hole to avoid snags and possible injury.  Where no lock-wire lug is...  Where no lock-wire lug is provided, wire should be applied as shown with caution being exerted that the wire is tightly wrapped around the fitting.  Small size coupling nuts shall...  Small size coupling nuts shall be wired by wrapping the wire around the nut and inserting it through the holes as shown.  Coupling nuts attached to...  Coupling nuts attached to straight connectors shall be wired as shown, when hex is an integral part of the connector.  I decided to try my hand at...  I decided to try my hand at "safetying," as it's known in the aircraft industry, on a blower pop-off plate I had laying around. I chose this object for no other reason than it had a number of fasteners in a circular pattern to practice on.  The first step was to drill...  The first step was to drill the heads of the Allen fasteners using the Graham Tool drill jig.  Once drilled, the bolts are...  Once drilled, the bolts are torqued to spec and the first loop of wire is ran through the head of the fastener. Note the relationship of the wire in regards to which end is on the top and which is on the bottom.  Using the safety wire pliers,...  Using the safety wire pliers, the length of wire between the first and second fastener is twisted using a right-hand, or clockwise, twisting method.  Next, the wire is pulled through...  Next, the wire is pulled through and around the second fastener. Again, note the relationship between the two wires.  I decided to try my hand at...  I decided to try my hand at a multiple fastener run and continued on to the third fastener. The result isn't beautiful but illustrates the basic technique.  This hub and rotor adapter...  This hub and rotor adapter is "safetyed" in a similar fashion.  To finish off the run, the...  To finish off the run, the last length is twisted after exiting the third fastener and the tab bent under and out of the way.  Here's another trio of fasteners...  Here's another trio of fasteners "safetyed." Note that the wire is twisted counterclockwise between the second and third fastener to keep the loop in position against the head of the second bolt.
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The Thinker??? - Haul Monitor
Ryan talks about the friendly badgering that goes on around the shop and overcoming obstacles that seemly pop up out of nowhere during a project....
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