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<p>[QUOTE=&quot;GDJMSP, post: 838276, member: 112&quot;]When it comes to mechanical doubling - that is it in a nutshell - the two strikes. There was an excellent article on mechanical doubling by Mike Diamond (a member here) in a recent <i>Coin World</i>. I would urge you to get a copy and read it.</p><p><br /></p><p>But simply put, the primary strike occurs when the hammer die and anvil die come togther. It ends in the microsecond that the hammer die has reached its lowest point at the end of its stroke. In that very microsecond the minting of the coin is at an end (and anything that occurs after that microsecond is considered to be damage).</p><p><br /></p><p>Up to now there is no mechanical doubling on the coin. But in the next microsecond, as the hammer die begins to retract, one or the other of the two dies moves. Think of this move being a bounce and it is easier to understand. It is that bounce that causes the secondary strike. </p><p><br /></p><p>During the bounce one die or the other hits the coin again. And since the die that bounced has moved out of its previous position it cannot and will not hit the coin in precisely the same place that it hit it during the primary strike. Nor will it come into complete contact with the coin. Only a portion of the die&#039;s surface will come into contact with only a portion of the surface of the coin.</p><p><br /></p><p>What this does is to smear or push part of the coin&#039;s design to one side or the other. That is what creates the flat, shelf-like appearance so common with mechanical doubling.</p><p><br /></p><p>What you have to remember is that all of this can literally take place numerous times, (to several coins) in the time it takes you to blink, for roughly 12 coins are struck in one second.</p><p><br /></p><p>Does that make it easier to understand ?[/QUOTE]</p><p><br /></p>

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