Homemade bending break
Note to teachers and youth leaders: For instructor lesson plans of these materials, contact the Department's Outreach and Education Division.
The primary difference between the frontiersman and the native Americans he encountered was that the native people knew little or nothing about metals, but the trader, trapper or mountain man depended on metal goods (knives, guns, traps, sewing needles) for his livelihood and survival. Because he lived far from trade sources and black-smiths, the frontiersman's com-fort and safety also depended on his skill in metal repair. To venture into the wilderness alone required him to be a blacksmith as well as tailor, hunter, carpenter, butcher and more.
Metalworking tools can be purchased at a hardware store. Supplies such as tin (black iron), sheet metal and sheet brass can be obtained either from a hardware store or by consulting the sheet metal heading in the yellow pages of a large city's phone directory.
In addition you will need a bench or machinist's vise and a sturdy work sur-face. Like leatherworking tools, most items listed will fit in a small tool box.
Metal used for projects in this unit falls into several categories. For projects such as a steel striker, old files and saw blades are superior. They are made from high carbon steel that can be worked easily and hardened well.
For projects such as the candle lantern, sheet metal, sheet brass or tin are best. Brass and sheet metal must be purchased. The best source of tin is old tin cans. Make sure the cans are not aluminum or alloy. True tin cans have crimped seams fastening the ends to the side. The side is one piece of metal soldered to form a cylinder. Soup cans and fruit juice cans are usually tin.
Metal comes in gauges indicating thickness. The lower the number of the gauge, the heavier the metal. For example, metal ductwork in a home heating system is approximately 24 to 28 gauge. This is probably the heaviest metal necessary for any project in this book. Tin cans are suitable for light projects-a candleholder, for example.
Old files and saw blades can be obtained from junk shops, flea markets and garage sales. Their cost should be almost nothing (unless they are antiques which should be avoided anyway).
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The steps for completion of a metalworking project are the same as those for leatherworking, woodworking and sewing.
First lay out the design on paper or cardboard. In many cases, layout can be done right on the metal without using a separate pattern. Use a straightedge and combination square to draw lines. Use a scratch awl to scribe the lines. Use a pencil to indicate for each line whether it is a bend line or a cut line.
Next, cut out the pieces with a hacksaw or tin snips. Lightly file freshly cut edges with the flat file to remove any burrs or irregularities. If you are using hardened metal, it must be softened or annealed before you can cut and "work" it. To soften, simply heat the metal to glowing red with the propane torch; then allow it to cool slowly. While heating, move the torch over the entire piece. Once the metal has cooled, it can be cut or bent with much less risk of breaking.
Drilling-Assemble the project by first drilling any necessary holes. Before drilling, mark the center of the hole by dimpling the surface with a nail or metal punch. This guides the drill bit and prevents it from wandering.
Bending-Next, make any bends required. Bends are accomplished in two ways. The simplest way is to use the brake bar or bending brake. Put the metal in the tool and align the scribed bend line with the proper marks on the brake. Work the handle and the bend is made.
If a bending brake is not available, three hardwood blocks will perform the Homemade bending break same task. Be sure the blocks are square. Clamp the metal between two of the blocks using C-clamps. Before clamping, align the blocks along the bend line. Put the entire assembly in a vise. Lay the third hardwood block on top of the clamped block on what will be the outside of the bend. With a hammer or mal-let, begin tapping the free hardwood block so the metal begins to bend. Continue, working back and forth along the block until the angle is formed.
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After fluxing, lay the pieces in the position they should be in when finished. They should be resting securely in this final position. If necessary, use clamps to hold the pieces in position. The parts should be secure enough that an accidental bump of the torch cannot affect alignment.
If the pieces must be clamped into position, pad the clamp jaws with heat retention material. Otherwise, the clamps will absorb the heat from the torch and prevent the metal pieces from getting hot enough to form a good joint.
With the pieces fluxed and securely positioned, apply heat to the metal near the intended joint. After several seconds of heating, touch the solder wire (unroll about 6 inches or 15 cm and hold so it projects from the palm of your hand between your thumb and forefinger) to the seam where the metal pieces overlap. If the metal is hot enough, the solder should melt immediately and flow into the fluxed area. If the solder does not melt immediately, remove it and apply more heat. Do not heat the solder directly with the torch. The result will be a weak joint.
The secrets of a good solder joint are (1) metal heated sufficiently so solder flows easily; (2) a clean, well-fluxed joint; and (3) a minimum amount of solder. Globs of solder indicate a poor, and probably weak, joint. Remember-the object of soldering is to heat only the parts being joined. Anything touching the metal will draw heat from the area being joined. Therefore, always pad clamp jaws, pliers and vise jaws with heat retention material to prevent heat loss. Metal is hardened by heating it to a high temperature, then cooling it suddenly. Hardening works best with iron or steel of fairly high carbon content, such as metal used in files and saw blades.
To harden or reharden metal, heat until the piece glows bright red. Then, holding the piece with pliers and padding of heat retention material, drop it quickly into a container of cold salt water. Metal is polished by rubbing briskly with emery cloth and then crocus cloth. Sandpaper and steel wool will also remove file marks and scratches.
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