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 Replies: 30 / Views: 2,831 |
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Pillar of the Community
United States
3663 Posts |
The only set-up strikes that I have seen are for new coin designs, for mints being added to producing existing series, or for mints testing new coining presses. Unless Philadelphia changed coining presses in 1998, I don't see why a set-up strike would exist. Orientation checks usually are done at full striking pressure. Alignment today is calibrated so closely that it, too, should be able to be tested at full pressure, although that would have been a different matter a century ago. The only remaining modern reason for a low-pressure set-up strike would be to dial in the minimum tonnage needed to produce an acceptable image (within tolerances), to minimize die wear. The clearest set-up examples I have seen are a series of 10-12 1964-D Kennedy half dollars showing a wide range of striking pressure. That series was fairly widely displayed out here in the 1970s and early 1980s, but I haven't seen it since then. I remember that some of the stronger strikes had visible rims, but not nearly as bold as the 1998 cent shown here. I've often wondered how that run of 1964-D half set-up strikes made it out of the mint, but a lot of weird things escaped the Denver mint back then. Proof-like specimen strikes of the 1964-D Kennedy half and very marginally canceled dies with nearly complete images (such as the 1983-84 Olympic commems) come to mind. Bottom line: I agree. The 1998 cent is a spectacular Greaser. |
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Valued Member
United States
254 Posts |
But the question is. Is it a WAM? |
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Pillar of the Community
United States
2775 Posts |
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The only remaining modern reason for a low-pressure set-up strike would be to dial in the minimum tonnage needed to produce an acceptable image (within tolerances), to minimize die wear. I believe they have recommended minimum for applied tonnage for each product line. Wouldn't the machines speed not also increase or decrease production rates and is that speed left to machine operators discretion? Thanks, Doug. |
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Pillar of the Community
United States
3663 Posts |
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Wouldn't the machines speed not also increase or decrease production rates and is that speed left to machine operators discretion? I can only answer this for what I understand about the Denver mint. The answer differs depending on the type of coining press. Denver switched from the old Bliss Presses to the current Schuler Presses in 2004 or 2005. (It wasn't long after the Wisconsin "Extra Leaf" quarter debacle, which happened on a Bliss Press.) The current Schuler Presses strike coins horizontally. Striking pressure, stroke rate, and pressure are all managed digitally, with self-adjustments based on real time data. A single die pair produces all of the coins ejecting from each press. These presses are a long way from the "olden days" (before 2004/5). The Bliss Presses were configured with four die pairs, but longer travel distances made production with four heads roughly on par with the Schuler production with just one die pair. The Bliss Presses were old, had years of use, and required more "babying" to operate. Getting them dialed in was an art. Yes, there were tolerance recommendations, but the press-to-press variances required tinkering. Maximizing die life was vital, because changing one die pair idled the other three pair on the press. Ever small reduction in striking force extended die life and allowed a longer run between servicing. This can be seen in the wide variances of strike quality for Denver coins pre-Schuler and the much more consistent quality of Denver coins in the Schuler era. Compare the mushy 1990s cents with the sharp satiny late 2000s and 2010s cents. (Now if we could only get the designs of the coins to match the striking quality . . .) |
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Bedrock of the Community
United States
74728 Posts |
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I can only answer this for what I understand about the Denver mint. The answer differs depending on the type of coining press. Denver switched from the old Bliss Presses to the current Schuler Presses in 2004 or 2005. (It wasn't long after the Wisconsin "Extra Leaf" quarter debacle, which happened on a Bliss Press.)
The current Schuler Presses strike coins horizontally. Striking pressure, stroke rate, and pressure are all managed digitally, with self-adjustments based on real time data. A single die pair produces all of the coins ejecting from each press.
These presses are a long way from the "olden days" (before 2004/5). The Bliss Presses were configured with four die pairs, but longer travel distances made production with four heads roughly on par with the Schuler production with just one die pair. The Bliss Presses were old, had years of use, and required more "babying" to operate. Getting them dialed in was an art. Yes, there were tolerance recommendations, but the press-to-press variances required tinkering. Maximizing die life was vital, because changing one die pair idled the other three pair on the press. Ever small reduction in striking force extended die life and allowed a longer run between servicing.
This can be seen in the wide variances of strike quality for Denver coins pre-Schuler and the much more consistent quality of Denver coins in the Schuler era. Compare the mushy 1990s cents with the sharp satiny late 2000s and 2010s cents. (Now if we could only get the designs of the coins to match the striking quality . . .) Very interesting and good information! Thank you for sharing! I learned another thing on CCF today!  Errers and Varietys.
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Valued Member
United States
420 Posts |
Thanx Coop for another valuable lesson in the art of ID'ing..
And thank you fortcollins for sharing scuttlebut out of the Denver mint..
Swamp
PS fortcollins: I hear ya n am with ya in re modern (cent) design choices.. However, given what they're being struck upon I find myself not caring as much as much as I once would have.. And given how "sharp" the obverse features continue deteriorating toward it seems sadly obvious "they" don't much care either..
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Pillar of the Community
United States
2775 Posts |
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Now if we could only get the designs of the coins to match the striking quality.  Thinking the days of high relief on business strikes is over for the time being. Read in a previous topics the horizontal Schuler press was introduced in 2002, about the same time the inverted die setup began to be mainstream. Thanks, Doug. |
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Pillar of the Community
United States
3656 Posts |
Wow that is amazing - Great find
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Pillar of the Community
United States
2738 Posts |
This is definitely a grease strike. The strong design rim and the uneven pattern of weakness (e.g. a strong bust of Lincoln) are clear evidence of this.
Also, the terms "die adjustment strike", "die trial", and "set-up piece" can never be justified. For any simple, centered weak strike you can never assign ultimate cause. However, multiple lines of independent evidence indicate that the vast majority of weak strikes in the marketplace are the result of spontaneous equipment malfunction in the middle of a press run. So the preferred terms are "weak strike" or "low-pressure" strike.
Error coin writer and researcher.
Edited by mikediamond
06/22/2018 12:12 pm
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Pillar of the Community
 United States
8518 Posts |
Thanks Mike, I will remember that.
Oregon coin geek.....*** GO BEAVS ! ! ! ***
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Bedrock of the Community
United States
74728 Posts |
Quote:
Also, the terms "die adjustment strike", "die trial", and "set-up piece" can never be justified. For any simple, centered weak strike you can never assign ultimate cause. However, multiple lines of independent evidence indicate that the vast majority of weak strikes in the marketplace are the result of spontaneous equipment malfunction in the middle of a press run. So the preferred terms are "weak strike" or "low-pressure" strike. Very interesting and very educational information! Thank you for sharing! I learn another new thing on CCF today. Errers and Varietys.
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Pillar of the Community
United States
2738 Posts |
Error coin writer and researcher.
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Bedrock of the Community
United States
74728 Posts |
Another interesting and very informative read. Thank you Mike Diamond!
Errers and Varietys.
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Pillar of the Community
United States
3663 Posts |
Quote:
Also, the terms "die adjustment strike", "die trial", and "set-up piece" can never be justified. For any simple, centered weak strike you can never assign ultimate cause. However, multiple lines of independent evidence indicate that the vast majority of weak strikes in the marketplace are the result of spontaneous equipment malfunction in the middle of a press run. So the preferred terms are "weak strike" or "low-pressure" strike. Mike, the 1964-D Kennedy series that I mentioned had what might have been provenance. I remember seeing a handwritten letter displayed in the frame with the series and seeing the label "set-up strikes" on the display. That's why I've thought of them as that. The last time I know those coins were displayed was the late 1970s or early 1980s. They were the kind of thing that made me look and think "that's interesting" and move on to what really interested me back then, completing my Buffalo nickel set. I was out of collecting after that for about 25 years because of work and family and all the other demands of life, so I have no idea if those coins are still in this neck of the woods. Maybe somebody else from the Front Range back in the day has a better memory on this. The equipment malfunction thought is interesting. I could definitely see a hydraulic system failure during a production run creating sequentially weakly struck coins. That's the best explanation I have heard for coins like this. Thank you!!! |
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Pillar of the Community
United States
2738 Posts |
Coining presses are mechanical, not hydraulic. Hydraulic presses are much too slow.
Error coin writer and researcher.
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Replies: 30 / Views: 2,831 |
First Page
Posted 06/19/2018 9:53 pm
