PART VI. Striking Errors:
Stutter Strikes:
Stutter Strikes due to planchet flexion (Type II):
Definition: A stutter strike is a rare error that can be thought of as the polar opposite of machine doubling. While the extra impressions of machine doubling occur after the downstroke of the hammer die reaches its lowest point, a stutter strike occurs before the downstroke has completed its downward trajectory. In a stutter strike, the hammer die makes initial light contact with the surface of the coin, but completes its descent in a slightly different position relative to the original point of contact. The result is a thin crescent of design at the outer margin of coin, distinctly separate from the definitive strike.
A stutter strike can result from movement of the die, movement of the coin, or expansion of the coin during the downstroke. It always occurs together with at least one other press malfunction or error. Associated errors include an off-center strike or broadstrike atop a stiff collar, an indent or partial brockage, or a loose die in combination with any of the aforementioned errors.
The Indian 1998 5 rupees below features a double row of denticles opposite a large indent on the reverse face. As with most Indian coins, the reverse face was struck by the hammer die. While the double row of denticles may appear to be a double-strike, closer inspection shows that it is, instead, a stutter strike.
In the case of this 5 rupees coin, the factors underlying the production of a double row of denticles appears to be the indent, in combination with a loose hammer die or die carriage. The presence of an intrusive planchet caused uneven pressure to be applied to the planchet represented by this coin. The area overlain by the intrusive planchet received the initial force of the strike, which tipped up the part of the planchet lying beyond the indent. The elevated outer portion of the planchet contacted the perimeter of the descending hammer die so that the former picked up an initial row of denticles. Simultaneous with that contact, the hammer die shifted medially and completed its downstroke, producing the second row of denticles along with the main strike. The main strike is misaligned relative to the obverse design, which was struck by the anvil die.
The stutter strike shown below is associated with an indent on the left side of the obverse face. The intrusive planchet was contacted first by the descending hammer die. This caused the right side of the underlying planchet to angle up and meet the hammer die on its way down. That light initial contact left a weakly-struck crescent on the right side of the coin that contains the TY of LIBERTY and the date. As the hammer die continued its descent, it compressed both planchets. This caused both planchets to expand in all directions. The expansion of the underlying planchet carried the lightly-struck crescent on the right side beyond the edge of the striking chamber. The hammer die then completed its descent, producing the definitive design.
The stutter strike lies lateral to the definitive design on both the obverse and reverse face. It is opposed on the reverse face by the original unstruck surface of the planchet.
