VOCABULARY TERMS: BASIN AND DIE CAMBER

Basin. The concaveness or sloping surface of a model, die or coined item. A die in this shape is said to have a CAMBER. The basin is formed by the rim and the DISHED area of relief. Coin models particularly are so shaped because of the requirement of a rim higher than any point on the relief and the fact coins are struck from a single blow. A slightly curved die face aids in the release of the coin after it is struck and one die is retracting. If the die face was flat it would cause the coin to “hang up” in the die. The pressure of striking causes the coin to adhere to the upper die. A BACKGROUND PLATE in this dished shape is also called a “basin.” Should the design be flat without any concaveness certain modern diecutting pantographs can create a basin shape and cut a die with a camber. The St-Gaudens 1907 $20 Gold ultrahigh relief is the most dramatic U.S. coin with a basin. See DIE CAMBER.
CLASS 03.4

REFERENCE: C70 {2017} Sholey (Craig) Nineteenth Century Medal Making Processes MCA Advisory 20:5 (September / October 2017) p 29-32.

Die Camber. A slightly domed or convex curvature of the table or background in a die. The die is purposefully domed so it may strike coins that are slightly concaved or basin shaped. The reason is that this camber will lower all relief below that of all the rim, thus with all design lower than the rim, it will reduce wear on the design while the coin is in circulation. The rim bears the brunt of all surface wear (until the rim itself is worn down to the level of the design).

Placing the camber in the die is intentional. It is often so slight that it is hardly noticeable to the human eye. Some mints require their artists to model a design on a basin-shaped background plate to create this camber in the model. Numismatic writer Walter Breen called the creating of die camber basining and described it as “imparting variable radius of curvature to the fields.”

However, with the modern die-engraving pantograph, particularly the JANVIER, a die can be cut with a camber from a flat pattern. Thus the die, hub or master die can be made with the desired camber from a flat model or pattern on a modern PANTOGRAPH. The total surface – device and lettering in addition to the fields – is lowered, ever so slightly near the rim, gradually increasing towards the CENTER POINT.

It is impossible to know how the basin shape was created on a coined piece by inspection alone (unless the coined surface is badly buckled by sinking). This condition may have resulted from any of the following: (1) use of an intended basin-shaped model, (2) die camber created by the pantograph, or (3) sinking in a worn die.

Die camber is different from a CONE BLANK or DOME BLANK which is the contour of a die prior to its being hubbed. It is also different from a BUCKLED DIE, or SUNKEN DIE, in old or worn dies. Sinking occurs in all dies ever so slowly from constant compaction during striking (badly sunken dies strike pieces with an irregular DOMED EFFECT).
CLASS 04.4

REFERENCE:
NC10 {1988} Breen, ENCYCLOPEDIA, p 524-525.

Note: Where possible I have decided to run several terms of related meaning at one time. Otherwise it will take many years (70 in fact) to publish the entire encyclopedia list one word per week at a time. You can read any term without cost on the Newman Portal (go to Encyclopedia – then Dictionary). For those who would like to have the printed draft on hand of all 4,154 terms I still have a few copies of the printed draft at $50 each. Contact Dick Johnson, 139 Thompson Dr, Torrington, CT 06790 dick.johnson@snet.net

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