My CONECA Must Unusual Award Coin

[koinpro]

Here is a neat one that I just shot images of for another forum to illustrate a point. It's a 1981-P dime that the Mint examined for me in 1985 (or so). It was described by them as a dime struck on planchet rolled to proper thickness with a copper reverse. They said that it was due to coolant being trapped between the copper core and outer layer of cupronickel during bonding. As the heat and pressure increased during the bonding process, the outer layer of clad (above or below the trapped coolant) burst leaving an area of exposed copper that was eventually rolled to proper thickness. Some of the clad layer was rolled into this blank which later fell away creating what appears to be a straight clip. The "clip" caused an ejection mishap and the coin was double struck. I won the Most Unusual Error Award for this one at CONECA's Errorama in 1986. I still own it. Not the most spectacular coin I own but one of my favorites.
Ken Potter
CONECA Public Relations

[diamond]

I think the Mint's explanation is bunk. This is an end-of-strip, tapered planchet error. On clad coins these are inevitably associated with a missing clad error. These errors vary in weight. Some weigh as much as a normal coin and others much less. I just published an article on these errors in Coin World.

[koinpro]

Mike,

I worked in a stamping plant for nearly 25 years and I can tell you I have never once seen a coil of strip that had a tapered lead or end. Strip is rolled to proper thickness, slit to proper width and fed onto coils of predetermined length. When the correct length is fed onto the coil it's cut with a shear die. There is no taper just a straight edge like you see on a blank with a straight clip. Tapers are due to low spots that can occur anywhere within the strip or edges of the strip at random.

Additionally, on the coin I show, you can see where the metal was that fell away from what was to ultimately be the reverse. It did not fall off the obverse. This is distinguished by the taper at each side of the straight edge. Notice that on the obverse it tends to wrap towards down to the reverse and on the reverse it's tapered upward around the area where the metal (probably clad) fell away. In effect, the obverse side would have appeared relatively normal while the reverse cradled the "extra metal" that fell away before the strike. All this is evidenced on the coin itself.

Other coins that are the result of similar mishaps are shown below.

[diamond]

Here's the thing. The two missing clad coins I feature in my recent article (a quarter and a dime) show a taper indistinguishable from that of a solid-alloy tapered planchet. The two nearly full-weight missing clad quarters I featured in an earlier column also show a slight taper. I have seen many other missing clad errors similar to these four coins and your specimen. It's inconcievable that all of these should have "rolling indentation" errors. Furthermore, your double-struck dime shows the taper terminating at a straight clip, just like many solid-alloy coins with tapered planchet errors. That would support its origin from the leading or trailing end of the strip.

To me it seems like these errors represent a failure to trim the end of the strip or a failure to trim it far enough into the strip to remove the area with the taper and the missing cladding.

[koinpro]

Mike,

I have several problems with your theory. First and foremost is that in 24 years of working in a stamping plant, I've never seen a coil with a tapered lead or end. Yes, I've seen ends damaged from the way they are secured on the coil and you will see band marks from banding, but not tapered as if there wasn't enough metal to fill the necessary requirement of thickness.

However, I have seen embedded metal that appeared to be rolled in and I have seen such metal fall out as a blank was transported to the feed mechanism or after being proceed further. This could occur anywhere in the strip including the lead and end of strip. However, because the leads and ends are such an infinitely small percentage of the entire strip, it is highly unlikely that most such errors originate from these areas and could cause a taper at some point.

Beyond homogeneous strip, clad strip that goes through a bonding process adds more possibilities of mishaps such as the one the Mint described to me.

The slitting of strip to proper width for a blanker also suggests that defects can occur here too but a taper would be possible here more from the strip being slit through a thin spot more than anything, in my opinion.

So far I've shown two additional coins, the 1977 dime and the 2005-S Kansas proof quarter with an exposed copper core rolled to proper thickness. Neither have a taper as in an "end of strip" tapered planchet scenario you suggest.

I'll show here another coin from my collection, a 1981-P dime (yep, another of the same date) that has a largely copper reverse, is rolled to proper thickness, and shows some defects in the form of "missing metal" that does not conform to your theory.

This piece has two areas of metal that fell out before the strike from what ended up being the reverse. The is no indication on this coin or any of the other coins I've shown here that both sides of the planchet were affected by the metal-loss. All four are largely normal on their one side (coincidentally the obverse on all of these coins), other than weakness of strike due to insufficient metal on the opposing side and ignoring the double strike on the one dime.

Additionally, this latest piece that I show, has two defects near the rim where the planchet thins, but the area in between is thick -- in fact thicker than normal. This is counter to the tapered planchet theory.

On a Tapered Planchet error, more often than not, you see what appears to be equal thinning on both sides of the coin -- not "gaps" from missing metal that fell out after the strip was rolled as we see on the coins here and no area of thickness interrupting the taper.

Additionally, the lips of a "clip" do not form up on a tapered planchet like we see on the 1981-P Dbl Strk dime. One one side (the reverse) the lips cradle an area were metal was missing and on the opposing side, we get quite the opposite effect suggesting that there was no metal missing from that side of the planchet and it began to flow to the side of less resistance.

With all this said, I have not seen your article nor the coins in question. I cannot state you are wrong about the coins you wrote about. There is always a slim possibility of a taper at the end of a strip -- I have just never seen one.

But for the coins I show here the evidence seems overwhelming to me that they are not the result of an end of strip scenerio and that the Mint is most probably correct in their assessment.

Ken






This image shows that the area in between the two low spots in the coin is thick. The low spots are pointed out by the white arrows.

[diamond]

I agree that some of these atypical clad errors do not conform to the expectations of a tapered planchet. In those cases I'm certainly willing to consider the possibility of a rolling indentation error (metal being rolled in and then falling out after rolling is completed). In fact I have a dime that I did not write up that is missing the reverse clad layer and that shows two shallow troughs within the exposed copper core.

But the vast majority of these overweight, full missing clad errors do show a taper at one pole that seem, at least in my eyes, to conform to a tapered planchet error. The terminal straight clip on your 1981-P dime provides added support for my conjecture.

Add to this the complete absence of fully clad coins struck on tapered planchets, and it would seem that these errors are hiding out as overweight missing clad errors.

In the end, it's probably the case that there is more than one etiology responsible for these errors.

I appreciate you taking the time to question my evidence and conclusions. It's always helpful to consider a contrary opinion.

[koinpro]

Mike,

It has been a very good discussion with lots to consider but I think we'll have to agree to disagree ... at least for now. You've peeked my interest and I'd like to see more of these coins and I do know I can round some up locally.


Ken