Signs of Feeder Contact Surprisingly Rare on Off-Center Strikes

By Mike Diamond

Off-center strikes are the result of a malpositioned coin metal disc (planchet or coin). A faulty feeder/ejector mechanism is presumably responsible for such mishaps. They can also be caused by something that impedes the insertion of the planchet or the ejection of the newly struck coin.

The vast majority of off-center strikes show no evidence that the planchet or coin was held in place by a feeder/ejector (henceforth referred to as a feeder). And that poses a bit of a mystery, especially for discs transported by rotary dial feeders.

A rotary dial feeder consists of several individual feeders that are bolted to a circular indexing plate. Each feeder consists of two so-called “fingers” that define a notch designed to carry the planchet into the striking chamber and the newly-struck coin out of the striking chamber.

The fingers have no independent role in moving the coin metal disc into and out of the striking chamber. Insertion and ejection are accomplished solely by the rotation of the indexing plate. Each incremental turn of the plate positions the next feeder notch and its contained planchet over the anvil die.

Shown above is an intact feeder in which the right “finger” was struck by 2000-D Maryland quarter dollar dies. This feeder was evidently composed of steel, rather than aluminum.

Aluminum feeder fingers are designed to break off when struck. Shown above is a 2007-D cent struck on a breakaway aluminum feeder finger.

A mistimed feeder should leave one side of the feeder notch positioned over the anvil die. That portion of the notch will be struck while the planchet contained within it receives an off-center strike. Confined by the feeder notch, the coin’s expansion should ordinarily be blocked and the coin itself deformed.

The illustrated off-center dime was deformed by contact with both sides of the feeder notch. I’ve assigned the term “bilateral machine part impingement” to this type of striking error (Coin World, May 25, 2015). The struck portion of the dime rested against the right side of the feeder notch. The two struck edges flowed against each other to form, on the dime, a “foreign object chain strike”.

The right side shows reduced convexity (relative to an unconstrained off-center strike), and the edge shows a long contact facet. The left side of the dime was pushed in as the unstruck portion of the planchet was driven into the left side of the feeder notch by the expansion of the struck portion. This created an indentation in the edge and another contact facet. Together they comprise a form of “intra-strike damage” (damage that occurs during the strike).

This dime was struck with the inverted die setup (reverse die as hammer die). This setup is generally associated with the Schuler press, along with use of a rotary dial feeder and breakaway feeder fingers. However, rotary dial feeders and breakaway feeder fingers were employed well before the Schuler press was widely adopted.

This dime is an outlier, as the vast majority of off-center strikes seen in coins struck by the Schuler press show no feeder/ejector contact. The exception to this pattern is double- and multi-struck specimens involving one or more off-center strikes. Such coins do usually show feeder contact.

Shown above is a 5-cent coin that received a relatively normal first strike and then three closely-spaced off-center strikes. Like the dime, this 5-cent coin shows a bilateral machine part impingement error.

Once in a while, a planchet or coin will escape the notch and wind up above or below the feeder. As a result, the coin will end up with a “struck through feeder” error (Coin Word, March 7, 2011).

Shown above is a triple-struck 1996-P 5- cent coin that was struck through one side of the feeder notch. The curved internal margin of the struck-through error marks the edge of the feeder notch. The impact nearly tore off the portion of the planchet below the feeder. This coin was struck with the traditional die setup (obverse die as hammer die).

It remains to be explained why so few single-impact off-center strikes show either a bilateral machine part impingement error or a struck-through-feeder error. After all, the disc would seemingly have no way to evade the dial feeder, which continually moves through the striking chamber and hovers over the anvil die at all times.

There are several possible explanations.

1. The unstruck portion of the off-center strike tips up and rides over the adjacent feeder finger. The problem with this scenario is that it would only apply to those off-center strikes with visible “cupping”. Many off-center strikes show little or no cupping. Moreover, in this scenario, the struck portion should still flow against the side of the adjacent feeder notch and develop a contact facet.

2. A feeder is struck and breaks apart, leaving a gap in the dial feeder. Any planchet that falls into this gap will be unconfined and would simply be pushed along by the next intact feeder. If struck off-center, the coin’s expansion would be unimpeded.

3. A gap develops between the dial feeder and the top of the collar. This could occur if the indexing plate becomes unstable and lifts up or the collar becomes unstable and drops down. In either case, planchets and coins that fall into this gap would be weakly advanced, so that many wind up in an off- center position. Positioned beneath the dial feeder, and presuming the feeder notches are positioned properly over the anvil die, the planchet will expand freely.

4. A tilted indexing plate. This would leave excess space between the feeder and the top of the collar at one pole, allowing for planchets and coins to fall into a gap between the indexing plate and the collar. It would also cause the depressed pole to scrape against the top of the collar. Note that the struck Maryland quarter dollar feeder shows slightly arcuate scrapes on the obverse (presumably bottom) surface. Many intact feeders show these same scrapes. Such scrapes are presumably due to an absence of clearance between the dial feeder and the top of the collar.

5. A tilted collar. This would have the same effect as 4.

None of these scenarios adequately explain the existence of extensive runs of identical off-center strikes from the same die pair. All these scenarios should produce quite a bit of variability in the extent and location of the off-center strikes produced during a particular press run. Clearly, further investigation into repeating patterns of off-center strikes and dial feeder mechanics is required!