Using the Fisch - Coin tight through the Slot?

15 October 2012

Tight through the Slot? 

The checking of coins with the Fisch requires judgement. Like how does the coin look compared to a known genuine coin, how tight is it in the recess, how tight through the slot. A coin at max diameter or thickness will be tight at the slot or in the recess. In fact, it is not necessary to force a coin through the slot when by looking you can see that it is very close to passing through. Does it pass the weight check?  Does it ring when checked with the Ringer?   

Why do I say this? Because what are you looking for: You are looking for a common metal fake with the Fisch. The Ringer can also detect common metal counterfeits but its main role is detecting tungsten counterfeits

Re-read the Fisch Principle. From the Fisch Principle: “A fake made from lead to exactly the same thickness and diameter as a genuine Krugerrand (or American Eagle) would be 35% lighter than the genuine coin. If made the correct weight and diameter it would be 54% too thick.”  A common metal fake will most definitely fail the Fisch checks of maximum size and minimum weight. 

Although unusual, the diameter of the coins appear to be at max or even a bit over max.  Given the minting process, the thickness is often the dimension that is oversize.

In the minting process a planchet (or blank) is held in a collar and struck by the die. The impact of the die forces the metal to flow towards the rim which then forms the raised edge of the coin. The coin has a raised edge to protect the devices (the images/writing on the coin) from excessive wear (as would occur if it were higher than the rim of the coin.)  As you can imagine in the minting, the smaller the coin, the more difficult it is to control the rim height. If the collar is a bit worn or loose, a coin will be of greater diameter than the mint specification. See the Fisch Family pages for many reports of coins outside of mint specifications. 

Modern coins have been minted in the same way for over 450 years. Aside from the advancement in the equipment that allows mints to make thousands of every day coins in an hour, the process is the same one:  A metal disk is held in a collar and stamped with force. The Fisch, on the other hand, has been made using modern technology with fine tolerances. 

Each Fisch is checked with disks at the maximum thickness and diameter of the coin and the minimum weight as specified by the issuing mint.