The incomplete punch (incomplete clip) is an infrequently encountered planchet error. It occurs when a punch (blanking die) fails to penetrate the coin metal strip completely. If the strip fails to advance properly, and a blanking die slices through the same general area a second time, you end up with a blank that carries a deep semi-circular scar on both faces.
The illustrated 1974 Jefferson 5-cent coin shows a classic incomplete punch. Each face displays a deep, sharply defined curved groove in the same position. Each groove penetrates the surface and appears on the coin’s edge where the groove terminates. The depth of a punch mark will naturally vary from coin to coin.
The appearance of an incomplete punch will be very different on an unstruck blank or on the unstruck portion of an off-center coin. A blanking die doesn’t so much slice through the coin metal strip as push through it. This is because the blanking die is not a circular blade; it is a flat-faced cylinder with a relatively narrow central tunnel that helps dissipate heat.
If the battery of blanking dies doesn’t penetrate the strip completely, it leaves a series of depressed circles in the upper surface of the strip and a corresponding series of elevated circles on the lower surface of the strip. After lagging behind and being punched through a second time, this portion of the strip yields a series of blanks, each of which shows a step-down on its upper surface and a step-up on its lower surface. When the blank is struck, the steps are erased and all you have left are two grooves.
Error dealer Jon Sullivan recently presented an off-center, copper-alloy cent whose unstruck portion carries a defect that shares many of the characteristics expected of an incomplete punch error (see photos). It was erroneously described by a major grading service as having a “double indent.”
The idea that this planchet was sandwiched between two planchets when struck is ludicrous, as neither face shows an indentation from an unstruck planchet. Instead, the planchet is bisected by a curved disruption that divides it into a crescentic half and an oval half. The oval half has been pushed in on one side and pushed out on the other side.
The metal has been visibly sheared through at the sharp step-down from the crescentic portion of the planchet to the oval portion. This presumably represents the original upper surface of the cent strip. The other side of the coin shows a sharp step-up from the crescentic portion of the planchet to the oval portion. This presumably represents the original lower surface of the strip.
A tiny off-center uniface strike is located midway along the outer curve of the oval section of the planchet. The outer portion of the last two letters of GOD can be seen at the tip of the struck tongue of metal. These die-struck obverse elements occur on the same side as the pushed-out portion of the planchet. This is not surprising as almost any planchet has a 50/50 chance of arriving in the striking chamber with its original down side facing up.
Some features of the planchet defect are not entirely consistent with an incomplete punch error. The two halves of the planchet should be parallel to the same horizontal plane; instead, the oval portion of the planchet meets the crescentic portion at an angle of around 30 degrees. This almost certainly represents damage that occurred after blanking. Such damage is also unsurprising, as the punch almost completely penetrated the strip, leaving a weak connection between the two halves of the planchet.
Also, both halves of the planchet should have flat surfaces, top and bottom. Instead, the “upper” side of the oval portion is distinctly concave in vertical cross-section while the “lower” side is convex. My guess is that the same mechanism that produced the bend also squeezed the oval portion of the planchet into its convexo-concavo topography. The upsetting mill is one candidate. If the bowl-like shape isn’t damage, then we’d have to invoke an unlikely, ad hoc explanation involving a mystery cylinder with a convex face.