Introduction: Blacksmithing Ancient Egyptian Copper Chisels
Step 1: Melt Your Copper
IMAGE 1: This is the crucible sitting in a bed of coal in the forge. It has to be hot enough to melt pieces of scrap copper that we collected. Copper melts at 1083 degrees Celsius, 1981 degrees Fahrenheit.
IMAGE 2: Here are three pour spouts (or cavities) that we've set into the sand. The cavity in the sand is formed by using a pattern (an approximate duplicate of the real part, or, in this case, three pipes that are slightly larger than the chisels). The cavity is contained in an aggregate housed in a box called the flask. Core is a sand shape inserted into the mold to produce the internal features of the part such as holes or internal passages. Cores are placed in the cavity to form holes of the desired shapes. Core print is the region added to the pattern, core, or mold that is used to locate and support the core within the mold. A riser is an extra void created in the mold to contain excessive molten material. The purpose of this is feed the molten metal to the mold cavity as the molten metal solidifies and shrinks, and thereby prevents voids in the main casting.
IMAGE 3: The crucible has finally reached a temperature hot enough to start putting bits of copper pipe into. As it melts and puddles at the bottom of the crucible it becomes easier to add more copper; the new additions begin to melt almost instantly.
IMAGE 4: Copper is notorious for popping; it is highly susceptible to any moisture in the air can add hydrogen to the molten copper. Copper should be melted under a floating flux cover to prevent both oxidation and the pickup of hydrogen from moisture in the atmosphere. In the case of copper, crushed graphite should cover the melt. Pure copper is extremely difficult to cast as well as being prone to surface cracking, porosity problems, and to the formation of internal cavities. The casting characteristics of copper can be improved by the addition of small amounts of elements including beryllium, silicon, nickel, tin, zinc, chromium and silver.IMAGE 1
Step 2: Adding Copper Pipe to the Crucible
IMAGE 1: Here Steve Bazay is hammering out scrap pieces of copper to add to the crucible.
IMAGE 2: Here we've hammered out scrap copper pipe and added it to the crucible. It takes quite a while for the initial puddle to form.
IMAGE 3: The copper is finally melting! When the molten metal reaches 1260oC, either calcium boride or lithium should be plunged into the molten bath to deoxidize the melt. The metal should then be poured without removing the floating cover.
Step 3: Ready to Pour
IMAGE 1: Here we've amassed enough molten copper to pour into the molds, with some left over for ingots.
IMAGE 2: Here the molten copper is being poured into the sand molds
IMAGE 3: This is the leftover molten copper which we are pouring into ingots forms
IMAGE 4: The molten copper has been poured and now we are waiting for it to solidify enough that we can release them from the molds.
IMAGE 5: This is the leftover copper, poured into ingot forms
Step 4: The Ingots
IMAGE 1: After the casts have been pulled from the molds they are quenched in a dunk bucket and then annealed again in the forge. Here are our three pieces with the mushroom cap overflow on top
IMAGE 2: The mushroom cap heads are overflow copper from the molds. We just ran them through the band saw to get rid of them.
IMAGE 3: The copper rods are now reheated in the forge and then shaping begins on the power hammer.
IMAGE[WIKI TIME!!} Power hammers are mechanical forging hammers that use a non-muscular power source to raise the hammer preparatory to striking, and/or to propel it onto the work being hammered. They have been used by used by blacksmiths, bladesmiths, metalworkers, and manufacturers since late in the first decade of the 19th century.
A typical power hammer consists of a frame, an anvil, and a reciprocating ram holding a hammer head, and is a direct descendant of the trip hammer, differing by storing potential energy in an arrangement of mechanical linkages and springs, in compressed air, in or steam, and by accelerating the ram on the downward stroke, providing more force and energy than simply allowing the weight to fall would do. Others, like steam drop hammers, use the power source to raise the ram, but let it be propelled solely by gravity.
Power hammers are rated according to the weight of the ram, and range between 25 pounds and 125 tons.
IMAGE 1: This is an old blacksmith technique for cutting a piece of metal off: heat it, drop a chisel into the hardie hole and hammer the metal over the chisel blade until it cuts through the piece.
IMAGE 2: The final shaping of the chisels is all done by hand. Here Steve forms the shape of the chisel by tapering the end and drawing it out.
IMAGE 3: The final shaping of the chisels is all done by hand. Here I am forming the shape of the chisel by tapering the end and drawing it out.
IMAGE 4: The final shaping of the chisels is all done by hand. Here Tina forms the shape of the chisel by tapering the end and drawing it out.
IMAGE 5: This is what the chisels look like after several runs through the forge, power hammer and us. For the show we want to emphasize the copper look so we are going to wire brush off the surface.
We cleaned them up to reveal the shiny copper and here are the finished pieces!
And here is some more wiki knowledge!
Copper may have been the first metal to be worked in Egypt, even before the metallic gold. The ores had a 12% copper content and given the scarcity of fuel and the difficulties of transportation one may well marvel at the fact, that they succeeded at extracting copper at all. In the beginning it was probably worked cold. In early Egyptian graves copper ornaments, vessels and weapons have been found as well as needles, saws, scissors, pincers, axes, adzes, harpoon and arrow tips, and knives.
This wide array of tools made of a metal difficult to cast and even with tempering too soft to be of use with any but the softest stone and wood shows the urgent need people felt for tools more flexible than what could be made of wood and stone.
Pure copper (like silver or gold) has a hardness factor of 2.5 to 3 on the Moh scale which is just about the same as limestone's. Naturally occurring copper is somewhat harder due to metallic impurities. Thanks to tempering, copper chisels and saws could be used to work freshly quarried limestone from the 4th dynasty onwards, but annealing with fire and hammering also rendered the tools more brittle. Because of the metal's softness, copper tools lost their edge quickly and had to be resharpened frequently.
When cutting and drilling grit was probably used, which lodged itself in the edges of the soft copper bits and performed the abrasive action.
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