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Methods of Attachment–welding, forging, brazing, and soldering


This article is all about attachment. But I don’t mean the girlie kind…

In austere conditions there is often a great need to attach objects. Sewing, tying, gluing, and press fitment are always basic options. For more secure attachments man has developed more robust means of Chemical (various glues and epoxies), Physical (nuts and bolts, nails, rivets and pins) and heat-based attachment such as welding, forging, brazing, and soldering.

This article will not go over the types of welding which require a forge or inert gasses, since those resource intensive topics are beyond the scope of even a single book.

Physical attachment such as with nuts bolts, rivets, nails, and pins should be familiar to anyone in the survival community. While there is not much to say about austere application of bolts, nails, and pins, one thing to note is a drilled hole past a nut particularly if you have a castle nut is a great place for a cotter pin to prevent loosening of the nut. With a bit of careful grinding of notches any nut could become a castle nut, please note that to prevent loss of threads you must be leave some good threading on one side to thread it back onto the bolt and re-establish the thread, and don’t heat till there is any chance of melting or spalling, go slow if you need to particularly with plastic or white metal nuts.

Riveting

Rivets are much more interesting for the survival community. While most people rarely if ever have experience with rivets they are a vital topic to understand, and have stood the test of time with minimal technology. While pop rivets and other modern consumable rivets are certainly interesting and useful, they are not our focus. We are interested in cold and hot rivets. The concept of both is simple we have a solid shaft with a preformed head on one side and the ability to form a second head on the other once it has passed through our materials.

Hot rivets are the attachment material of the industrial age, heating steel bolts, catching in buckets and using a rivet gun to mold hot steel before it cools and contracts. Cold rivets are of softer material which can be deformed while still cool without adding sufficient stress to crack. While it is possible to hot rivet in austere conditions, there is a steep learning curve and sometimes only one chance to get it right before the rivet cools. The human skill required is one of the big reasons rivets were displaced by nuts and bolts in construction. Cold rivets however just require patience and materials. The two most commonly used cold rivet metals are copper and alloys, and mild steel. Plastic rivets are great means of attaching snaps etc. to cloth, but beyond the scope of this article.

Copper rivets are commonly purchased or homemade, and that is of interest to us. Homemade copper rivets are made using a forming die and copper wire which has holes drilled in various depths for various widths of material to be joined. These dies can be purchased or made.

Essentially two matching blocks of mild steel are bolted together tightly and holes are drilled at the join of the two plates. Please size your drill bit to the size of the wire, and make sure the two pieces are very tightly bolted together and do not drill the final diameter first, drill a pilot and use a series of bits to achieve the final size. To use a piece of copper wire is inserted into the block for the desired depth (e.g. the width of the two work pieces to be riveted) and using a ballpeen hammer a head is formed with small tapping strokes. Once the head is flush and flat against the block, it can be unbolted and the new cold rivet removed. During assembly with a rivet the same process is used to form the 2nd head, a rivet is inserted through a pre-drilled hole of appropriate size (slightly larger than the shaft, but always smaller than the head of the rivet) and a new head is made on the opposite side, making sure to support the original head of the rivet.

An easier and sturdier rivet can be made with mild steel nails, a preformed head is present, and all that is needed is to:

Drill a slightly larger hole than the diameter of the shaft of the nail

Pass the nail through the two work pieces and cut off the excess nail on the other side (remembering to leave some shaft to form the new head.)

Repeat the same basic process of using a ballpeen hammer to fashion a new head on the exposed side. Remember to use a support on the head side of the nail or you will just be pounding the rivet back out.

Importantly, the strength of these rivets is limited by the size of the new head formed, and the strength of a material that can be cold hammered by hand. Obviously multiple rivets are commonly used for industrial purposes so a similar concept should be used. If there is a preexisting hole too large for your rivet such as when a spot weld has been drilled out, bumper washers can be used to decrease the diameter of the hole.

Finally there is always the option to buy rivets, particularly blind rivets which can be very useful.

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Welding

Hot joining of metals has been done since time immemorial. However our interest in an austere resource poor setting is limited to 3 processes, welding, brazing and soldering. Forging is not within the scope of this article. Please note there is slightly more chemistry involved in heat processes as the oxidation of metals and the chemical bonds between dissimilar metals becomes relevant. Oxidation of iron is rust, not a desirable component of a join, which in addition to weakening the join, is a site for further oxidation. Other undesirable materials such as dirt, grease, shavings, etc also will weaken a joint, or prevent adhesion or wetting of the filler. Please clean the area to be joined well before proceeding. Further some oxidation is inevitable when hot metal is exposed to oxygen.

There are two primary processes to minimize this from occurring, Flux and inert gas. Flux is a compound which prevents exposure of the work to oxygen, or is a scavenger of oxygen and is used in soldering, brazing, SMAW or stick welding and flux core welding. Inert gases such as argon and less reactive gases such as carbon dioxide are used in industrial processes such as MIG (metal inert gas) and TIG (tungsten inert gas) welding. While MIG and TIG welding processes are commonly used, and create excellent and strong welds, the inert gas is a requirement to prevent oxidative embrittlement of the join, which can lead to failure. In an austere environment the gases used would not be available, and unlike flux welding the gases are not easy to store nor are they cheap to store.

The key difference between the three processes is the differences between the melting temperature of the work pieces versus the filler, and the proximity of the two work pieces. Soldering is a process which can form strong attachments, most metal plumbing is joined with lead free solder, and many wire joints are secured with solder. The process is simple, a heating implement, e.g. soldering iron is applied to the work piece, which when it has been heated adequately will melt the solder when applied. Please note that the soldering iron should not be applied directly to the solder, but rather the solder should be scratched onto the heated work piece until the solder melts freely to form a join. Brazing is similar in principle, but with materials which tend to be stronger, and do not flow as freely such as copper or bronze. In this case the gap to be filled needs to be small enough that the filler metal is drawn into the gap by capillary action rather than flowing freely. Consequently brazing is often used more for industrial manufacturing rather than for home repairs.

It Takes Skill

There is a reason industrial welders make the money they do, quality welding is not as easy as it looks, competency in industrial welding takes hundreds if not thousands of hours, e.g. years of apprenticeship. Competent welding with decent equipment might take only a few dozen hours, but it would be better to learn now, particularly from a formal instructor than later with inferior or scavenged equipment. As is always true your fund of knowledge is more important than your stockroom of equipment, and competent practice makes perfect. Welding involves a great deal of heat and electricity. Meaning you should plan for your personal protective equipment assuming you don’t have a working hospital in TEOTWAWKI. Welding gloves, Welding mask, and garb that covers from head to toe is the bare minimum. The process of electrical welding generates UV radiation stronger than exposure to the sun, very severe burns can occur without notice just from the light of a weld; take care of your skin as burns in that situation could become fatal without quality medical care. The same exposure to your eyes could very quickly lead to blindness; even experienced welders do not fool around without goggles.

SMAW or stick welding is probably the best austere welding technique available to us. The problem is that quality stick welds are more technically difficult to perform than other types of welding. If your plan is to use car batteries and salvaged sticks to weld using jumper cables, it might behoove you to take a class and practice beforehand. The basic theory is using a welding rod in air to complete a circuit, electricity flows from the hot side of a source, through a rod holder or stinger, through the rod, spans the gap of air making an arc through to the work piece to the clamp on the work piece and back to the source to complete the circuit. The arc in the air is the critical place that electricity becomes heat and welding occurs, too close and there is just conduction through metal or there is excessive flow and too far and the arc is lost or there is the tendency to spatter. When striking an arc, the protective layer of the rod needs to be struck off, so the action is like striking a match.

There are three main causes of joint failure: undercutting, slag inclusion, and porosity. If the heat erodes the work pieces without adequate replacement with filler, the join can fail this is more often the case with high amperages. The two most common causes of slag inclusion are remnants of cold flux inadequately removed before re-welding a section as the cold slag can enter the molten metal and cause a failure, or when the angle is too steep some of the flux from the welding rod is incorporated in the edge of the colder weld as slag. If the filler was inadequately pooled, or too little flux is present the weld can become porous and fail, particularly if the arc length as determined by voltage is too high. In some ways welding is a bit like shooting, where body position, comfort and focus are important. In welding your position should be made as comfortable as possible to maintain rod angle at around 15 degrees, making sure to relax the hand holding the stinger.

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The distance from rod to pool is important as is the location of the pool being formed for 1/8” 6011 around 1/8” away. Moreover, just as in shooting where the natural tendency is to focus on the target, when actually the front sight should be the focus, it is not the arc or light you should focus on but rather the molten pool which should be where you concentrate. In some ways it is also like caulking, the speed you travel, and the angle you deposit your weld will create different widths and shapes of bead, for welding it’s not a bead but rather a pool which will be altered by those considerations. The width of weld should be between 2-4 times the diameter of the rod, circular or weaving motions allow for a wider deposition.

Finally, amperage or power will affect the depth and heat of a weld, unfortunately this is probably this biggest issue with the car battery jumper cable idea, the ability to tune the amperage e.g. the heat of the weld is going to be more limited when you only control voltage rather than amperage with your batteries. To reiterate, if there is excess spatter most likely there is a dirty work piece, excess moisture, or the arc length (voltage) is too high, the arc needs to be as short as practical to ensure an orderly path of current so the weld and pool is orderly as well. If there is excess sticking of the rod, or the pool is not adequately liquid e.g. it is not spreading well, the arc length is too short. Too high an amperage will lead to excessive liquidity of the metal and undercutting, if it looks burned out or you see loss of the work piece at the weld, consider turning down the amperage. Too low an amperage will decrease ability to start the arc, and will lead to narrow, poorly penetrative welds which in the worst case will not have bonded to the work piece, lack of fusion. These are starting points in welding which may take years to master.

Welding Rod Selection

While there are many rods of various chemistries for many purposes, until you can disagree from your experience, I would suggest 1/8” 6011. The 6 refers to the ideal tensile strength of the weld e.g. 60,000 psi, when most work steel would be somewhere near 36,000 of course remembering that this is the ideal maximum, so strong enough for our purposes. The 7 series electrode rods tend to be more finicky in a variety of ways either storage or welding conditions or metals, and can be explored with more experience. 6011 is an electrode rod which can burn through contaminant on less than ideally clean work pieces, can penetrate well, is easier to store, and can be used on most steel. It can be used with both AC and DC power sources, and can be used in all positions. When you know enough to need more than 6011, you will know more than the scope of this article.

Spending the small amount for a welding power source is probably worth the expense and effort particular if you are going to weld enough to maintain your skills. While I have taken pains to emphasize established skill and personal protective equipment (PPE), if need be a set of jumper cables, gloves, and a pair of sunglasses (you will get UV burn) can be used in a life or death situation, and a number of 12 and 6 volt batteries can be strung in series to provide a power source. You probably need around 30-36 volts worth, so at least one 6 volt is probably worth the trouble, otherwise three 12 volts will work in a pinch. Run the 4 cables in series from – Work piece to positive battery 1 – Negative battery 1 to Positive battery 2 – Negative battery 2 to positive battery 3 – Negative battery 3 to Stinger.

Flux-cored welding is technically much easier than stick welding but requires more expensive equipment, and more consumables. The basic principles of safety and PPE are similar; however inspection of the contact tips is an important distinction. Instead of moving the stinger closer to the work to maintain an arc length, the wire is fed into the work from a spool. Likely the best wire to start with is E71T-11, but if you choose another wire ensure you use the recommended feed rates and amperage.

Good Luck, Be Safe, and Practice.



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