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by George Wilkinson
Two exciting varieties to collect. Two formidable tasks that require a steady stream of knowledge, information and most importantly, help if you decide to explore their potential enjoyment and challenge. Here is some information and ....help.
You should be familiar with the minting process before you dwell to deeply into acquiring RPMs and OMMs. It would be wiser to have more than just a cursory knowledge of the minting process of course, so it is recommend that you try to obtain a book or reference on this subject when you can.
RPM and OMM varieties are closely associated with the DIE as part of the overall minting process, so it is also highly recommended that you at least perceive how a DIE is created and obtain reference materials on this specific subject too. As you read this RPM and OMM information, you will understand the importance of gaining knowledge about the die-making process.
At the mint, a die is created. When the die is almost finished by the mint workers there comes the task of placing the mintmark on the die before it will be used to produce millions of coins.
The mint employee who puts the mintmark on the die is commonly referred to as the ENGRAVER. The engraver is sitting behind a counter or table. In front of him or her will be clamps or a device commonly know as a "vice". The die is secured between this clamp or vice so it will not move during the remainder of this process. On the table nearby, the engraver will have a detailed sketch or drawing of the coin design. On this drawing there will be a special highlighted area where the mintmark is to be placed. By "area" we are referring to a specific designated place on the die that is much wider and longer than the actual size of a mintmark. There is plenty of room or latitude for the engraver to work within. This latitude explains why you will find a "S" mintmark say, for 1955 cents, in different locations under the date. For instance, on one die for 1955 S cents the mintmark was placed just to the right or east under the "9" of the date. On another die the mintmark is found directly under the "5" of the date. Both mintmarks are within the space or area shown on the sketch, yet in different locations.
The mintmark punch is typical of punches you can purchase at any hardware store. At the mint, the shaft of the punches are color-coded by using different colors of paint so the engraver can easily determine which punch has the mintmark of "D" or "S" and so on. The shaft of the punch is "V" shaped. This "V" shape grooving on the side of the shaft allows the engraver to readily "feel" that the punch is in the proper unright (or normal) position. At the end of the punch is the letter of the mintmark in its normal size, shape, etc.
The engraver looks at the sketch and the location or area where the mintmark is to be positioned or placed. Once the engraver is satisfied that the "V" shaped grooves are in his hand correctly and that the tip of the punch that has the mintmark of "D" or "S", etc., is the proper position, the thick end or top of the punch is hit firmly by a mallet.
How hard is the punch hit ? However hard the engravers experience, expertise, judgement and ability deems appropriate. How many times is the punch hit ? However many times the engravers experience, expertise, judgement and ability deems appropriate. No one really knows the answer to this question. But one thing is for sure - RPM'ers and OMM'ers can at least intelligently guess how hard and how many times. That's one of the primary reasons they collect these varieties in the first place !
It is generally accepted consensus of RPM and OMM collectors that the engraver strikes the punch with the mallet more than one time in order to assure that the mintmark is sufficiently imprinted into the die face. However, it is equally noteworthy that many times the mintmark is placed on the die with only one blow to the mallet in the opinion of some experts.
RPMs occur after the engraver strikes the mallet with the first blow to the top of the punch. Remember that the mintmark punch is hand held and struck by the mallet in this manner. After the first blow, the engraver will check that the mintmark has been placed inside the designated area that is on the sketch. A careful check will also be made to assure that the mintmark punched into the die is clearly visible and sufficient enough for the coining process. If, in the judgement of the engraver, another blow with the mallet is required the punch is placed back on top to the original mintmark and struck again, or again, or again, or .... until the engraver is satisfied.
The exact repositioning of the tip of the punch on top of the mintmark already placed on the die requires a steady hand, keen eyesight, and solid nerves. If the mintmark at the tip of the punch for the second strike is not positioned exactly on top of the existing mintmark then a RPM has been created. If a third, fourth, fifth, six, etc., blows occur then multiples of the mintmark can and have appeared. This inaccuracy is the foundation for the joy of searching for RPM's !
Photomicrographs provided by Mr. Z
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