WHAT TYPE OF COIN PRESS was used in the Bombay Mint in the late 19th Century?

Insider2Insider2 Posts: 12,813 ✭✭✭✭✭
edited November 9, 2019 8:40AM in U.S. Coin Forum

When we look at many of our AU/MS coins, especially the large ones, we can see radial flow lines. They are best seen near the coin's rims. The flow lines become longer, deeper, and more noticeable on coins as the die is used.

I have imaged a "dollar sized" silver British trade dollar struck at the Bombay Mint. The lines on this coin are not in the usual radial direction! They are curved away from the center. I'm trying to understand why.

Knowledgeable numismatists have said that steam-operated screw presses were sent to the Bombay Mint.

I think this discussion should be moved to the World Coin Forum.

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Comments

  • HemisphericalHemispherical Posts: 8,270 ✭✭✭✭✭

    Spiral like lines etched into the the die that was not made by the authorized source. My WAG.

  • jmlanzafjmlanzaf Posts: 10,010 ✭✭✭✭✭

    I assume you mean whizzing before striking? If the coin were whizzed later, there would be lines on the devices as well.

  • JimnightJimnight Posts: 2,648 ✭✭✭✭✭

    Maybe stretch lines from striking pressure?

  • PerryHallPerryHall Posts: 37,037 ✭✭✭✭✭

    Since it's limited to the fields, I'd assume it from polishing the die.

  • Insider2Insider2 Posts: 12,813 ✭✭✭✭✭
    edited November 7, 2019 1:38PM

    @jmlanzaf said:
    I assume you mean whizzing before striking?

    If the coin were whizzed later, there would be lines on the devices as well.

    Good point! :).

  • TommyTypeTommyType Posts: 4,357 ✭✭✭✭✭

    Throwing out a WAG, since I have no real knowledge about the time frame we are talking here....

    But would a screw press cause a different flow?

    Part of me likes the idea....the radial direction might be influenced by a slight circular "twist" of the dies...

    But...that same twisting motion would seem to also cause significant "strike doubling", as we call it. Shearing of the design elements...

    Anyway, I'd focus on how the presses and equipment are different than what the US uses??

    Easily distracted Type Collector
  • ms70ms70 Posts: 11,319 ✭✭✭✭✭

    I suppose the dies could've been loose in the press to a tiny degree causing rotation on strike?

  • CaptHenwayCaptHenway Posts: 27,183 ✭✭✭✭✭

    I have seen those on BTD's. Perhaps some sort of rotary brush was used against the face of the die, causing lines that spiral outwards.
    THis is just a guess.

    ... --- .-.. --- -. --. --..-- .- -. -.. - .... .- -. -.- ... ..-. --- .-. .- .-.. .-.. - .... . ..-. .. ... .... ..__.
  • LindeDadLindeDad Posts: 18,741 ✭✭✭✭✭

    Repairing a rusted die?

  • KliaoKliao Posts: 1,018 ✭✭✭✭

    Die polishing marks?

    Young Numismatist here. Enjoy collecting coins and selling items to fund my collection

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  • kazkaz Posts: 7,099 ✭✭✭✭✭

    My understanding is the "flow lines" are from gradual erosion of the dies as they are used, and proceed radially from the center. these look more like lines from some device used to prep/polish the dies like a rotating wheel with an abrasive on it, or maybe a rotating wire brush (although I am not sure how well that would work on hardened die steel).

  • KOYNGUYKOYNGUY Posts: 28 ✭✭

    T.D. Is right again, Rotary brush used on B.T.D. dies is S.O.P., To the novice mint state coins look whizzed. Incuse for whizzed coins, raised for "whizzed" dies. J.P.

  • Insider2Insider2 Posts: 12,813 ✭✭✭✭✭

    ANSWER TOMORROW. There are enough clues i this discussion already. That plus a little research...

  • rickoricko Posts: 69,503 ✭✭✭✭✭

    Definitely looks like a die issue to me....will check for the answer later. Cheers, RickO

  • messydeskmessydesk Posts: 16,223 ✭✭✭✭✭
    edited November 8, 2019 6:09AM

    Most of my British Trade Dollars are like that. There are no flow lines in the field on the coin shown. They're polishing lines. Flow lines would start to blur the dots and the corners of the encircling pattern.

  • Insider2Insider2 Posts: 12,813 ✭✭✭✭✭

    This discussion has proved to be an eye opener for me. It's something I thought would be answered right away especially on the world coin forum. Now I realize I misjudged the difficulty!

    Usually, an answer to almost anything can be found on the Internet in less than a minute. So, last night I went on the Internet to provide some links for everyone. After ten minutes of searching, I was beginning to doubt if what I learned about these coins while authenticating a collection in the early 1970's was actually true! Finally. I found confirmation of the answer in two short sentences on two different pages from two different books on the numismatics of India!

    I'm not going to reveal the answer yet. >:)

    I'll give a hint. These lines are not scratches or caused by a polished die. The characteristic is commonly seen on many different coins of all sizes.

  • KliaoKliao Posts: 1,018 ✭✭✭✭

    Casting lines if it’s a fake?

    Young Numismatist here. Enjoy collecting coins and selling items to fund my collection

    Please see my eBay store for jewelry and a few coins!
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  • Insider2Insider2 Posts: 12,813 ✭✭✭✭✭

    @Kliao said:
    Casting lines if it’s a fake?

    The coin is authentic. As for "casting lines," if this coin were a cast counterfeit, most of these lines (depending on the quality of the cast) would be transferred from the genuine coin.

  • PerryHallPerryHall Posts: 37,037 ✭✭✭✭✭

    When a master die is made from a plaster model, a Castaign machine is used to cut the master die. It works like a pantograph by using a stylus to trace the surface of the plaster model so the cutter can copy the design into the master die. These circular lines could be trace remnants of the cutting of the master die which is transferred to the working hub and then to the working die.

  • Insider2Insider2 Posts: 12,813 ✭✭✭✭✭

    @PerryHall said:
    When a master die is made from a plaster model, a Castaign machine is used to cut the master die. It works like a pantograph by using a stylus to trace the surface of the plaster model so the cutter can copy the design into the master die. These circular lines could be trace remnants of the cutting of the master die which is transferred to the working hub and then to the working die.

    NOPE. Don't over think this.

  • Moxie15Moxie15 Posts: 105 ✭✭✭

    I do not know if I can put this into words that make sense, and if I come close it is most likely wrong.

    The face of the planchet or the die had a very thin coating of oil or grease on it. Liquid cannot be compressed so as the die struck the pressure increased and the temperature increased the liquid looked for an easy route to move along pushing the metal into an unusual pattern.

  • Insider2Insider2 Posts: 12,813 ✭✭✭✭✭

    @Moxie15 said:
    I do not know if I can put this into words that make sense, and if I come close it is most likely wrong.

    The face of the planchet or the die had a very thin coating of oil or grease on it. Liquid cannot be compressed so as the die struck the pressure increased and the temperature increased the liquid looked for an easy route to move along pushing the metal into an unusual pattern.

    Very thoughtful but not the reason in this case. This is a struck coin using a normal die.

  • lkeneficlkenefic Posts: 4,703 ✭✭✭✭✭

    Perhaps someone attempted to buff out spots on a rusted die? However it was done, it seems uniform...

    Collecting ... dust

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  • Insider2Insider2 Posts: 12,813 ✭✭✭✭✭

    @lkenefic said:
    Perhaps someone attempted to buff out spots on a rusted die? However it was done, it seems uniform...

    Nope. Hint, this coin is an original MS example. You don't need to see the entire coin to guess what happened to leave these curved ridges.

  • Insider2Insider2 Posts: 12,813 ✭✭✭✭✭
    edited November 8, 2019 1:38PM

    @ifthevamzarockin said:
    Good chance the cat is going to suffocate before you let it out of the bag. :'(

    OK, The effect has little to do with the condition of the dies.

  • HemisphericalHemispherical Posts: 8,270 ✭✭✭✭✭

    I know it cannot be Canada’s anti-CF radial lines. ;)

    Awaiting...

  • ifthevamzarockinifthevamzarockin Posts: 1,841 ✭✭✭✭✭

    @Hemispherical "anti-CF radial lines."

    I think you are on to something there. :D

  • messydeskmessydesk Posts: 16,223 ✭✭✭✭✭

    This is going to be one of those things that makes me feel like an idiot when you divulge the cause.

  • Insider2Insider2 Posts: 12,813 ✭✭✭✭✭

    I'm glad I >:) posted this on the US forum.

    The image shows curved metal flow on a genuine British Trade dollar struck at the Bombay Mint in India at the turn of the previous Century. It was struck with normal dies. There is no evidence of any die polish, rust, or abrasion on the dies. This effect is very common on coins of British India. If the dies were loose, there is no way to tell from this image. So, how was this acceptable characteristic (its the way the coins come) produced on a coin at the Bombay Mint 120 years ago?

    l

  • CaptHenwayCaptHenway Posts: 27,183 ✭✭✭✭✭

    @Insider2 said:
    I'm glad I >:) posted this on the US forum.

    The image shows curved metal flow on a genuine British Trade dollar struck at the Bombay Mint in India at the turn of the previous Century. It was struck with normal dies. There is no evidence of any die polish, rust, or abrasion on the dies. This effect is very common on coins of British India. If the dies were loose, there is no way to tell from this image. So, how was this acceptable characteristic (its the way the coins come) produced on a coin at the Bombay Mint 120 years ago?

    l

    Smoke and mirrors.

    ... --- .-.. --- -. --. --..-- .- -. -.. - .... .- -. -.- ... ..-. --- .-. .- .-.. .-.. - .... . ..-. .. ... .... ..__.
  • ifthevamzarockinifthevamzarockin Posts: 1,841 ✭✭✭✭✭

    @TommyType said:

    This just turned into 101 ways to beat a dead cat :D

  • Insider2Insider2 Posts: 12,813 ✭✭✭✭✭
    edited November 8, 2019 3:56PM

    I'm going to post the answer that I learned and you guys can argue that it cannot happen as it is not seen on US coins made with a similar press.

    @TommyType said:

    Throwing out a WAG, since I have no real knowledge about the time frame we are talking here....

    But would a screw press cause a different flow?

    Part of me likes the idea....the radial direction might be influenced by a slight circular "twist" of the dies...

    But...that same twisting motion would seem to also cause significant "strike doubling", as we call it. Shearing of the design elements...

    Anyway, I'd focus on how the presses and equipment are different than what the US uses??

    These coins were struck on old screw presses. The image shows curved flow lines due to erosion of the die as more and more coins were struck in the same way that "radials" occur.

  • ifthevamzarockinifthevamzarockin Posts: 1,841 ✭✭✭✭✭

    So no more cats die... LOL :D

  • AUandAGAUandAG Posts: 21,486 ✭✭✭✭✭

    Okay, you screwed the cat it seems............

    For real?

    bob

    BST deals: Dozens of buys/sells. Will provide a list upon request.
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  • ifthevamzarockinifthevamzarockin Posts: 1,841 ✭✭✭✭✭

    "These coins were struck on old screw presses. The image shows curved flow lines due to erosion of the die as more and more coins were struck in the same way that "radials" occur."

    Respectfully disagree..... I will post after we kill a few more cats.

  • ifthevamzarockinifthevamzarockin Posts: 1,841 ✭✭✭✭✭

    @AUandAG said:
    Okay, you screwed the cat it seems............

    In about 58 - 67 days we can sell the kittens! :D

  • Insider2Insider2 Posts: 12,813 ✭✭✭✭✭
    edited November 8, 2019 4:36PM

    @ifthevamzarockin said:
    "These coins were struck on old screw presses. The image shows curved flow lines due to erosion of the die as more and more coins were struck in the same way that "radials" occur."

    Respectfully disagree..... I will post after we kill a few more cats.

    Excellent!

  • Moxie15Moxie15 Posts: 105 ✭✭✭

    So what am I missing?

    If memory serves...
    The die on a screw press should remain in one position. I t should not turn with the turning of the screw. Like a vice the screw presses against the back of the jaws holding the die.

    so how does it form the curved flow lines?

  • thefinnthefinn Posts: 1,327 ✭✭✭✭✭

    Not a curry vindaloo huh?

    thefinn
  • thefinnthefinn Posts: 1,327 ✭✭✭✭✭

    So why isn't this seen on coins from the US, GB or France struck on a screw press?

    thefinn
  • AUandAGAUandAG Posts: 21,486 ✭✭✭✭✭

    A "screw" is just the mechanism that drives the dies together. Screw turns but dies don't. Think of a tire jack that operates with a 'screw" .

    bob :)

    BST deals: Dozens of buys/sells. Will provide a list upon request.
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  • kazkaz Posts: 7,099 ✭✭✭✭✭
    edited November 8, 2019 5:03PM

    @PerryHall said:
    When a master die is made from a plaster model, a Castaign machine is used to cut the master die. It works like a pantograph by using a stylus to trace the surface of the plaster model so the cutter can copy the design into the master die. These circular lines could be trace remnants of the cutting of the master die which is transferred to the working hub and then to the working die.

    Just a point on terminology, the Castaing machine was used to apply the edge lettering on early coins such as bust halves. The Janvier reducing lathe was used to make the master die.

  • jmlanzafjmlanzaf Posts: 10,010 ✭✭✭✭✭

    @AUandAG said:
    A "screw" is just the mechanism that drives the dies together. Screw turns but dies don't. Think of a tire jack that operates with a 'screw" .

    bob :)

    True, but that could impart some residual torsion if the screw is perpendicular to the die? If the die is at all loose, why can't the die rotate slightly?

    That said, I don't see how that explains the curved flow lines in the fields but no corresponding rotational signature on the devices. Or is that what I'm seeing up by the rim?

    As you point out, the screw is really delivering most of the force in the same direction as a standard press so the flow should, I would think, also be radial.

    @insider2 How do we know it isn't die polish?

  • PerryHallPerryHall Posts: 37,037 ✭✭✭✭✭

    @kaz said:

    @PerryHall said:
    When a master die is made from a plaster model, a Castaign machine is used to cut the master die. It works like a pantograph by using a stylus to trace the surface of the plaster model so the cutter can copy the design into the master die. These circular lines could be trace remnants of the cutting of the master die which is transferred to the working hub and then to the working die.

    Just a point on terminology, the Castaing machine was used to apply the edge lettering on early coins such as bust halves. The Janvier reducing lathe was used to make the master die.

    You are of course correct. I can't believe I got the two terms mixed up. I must have had a senior moment. :D

  • messydeskmessydesk Posts: 16,223 ✭✭✭✭✭

    I'm now wondering if this is an exercise in not trusting everything you see in print.

  • divecchiadivecchia Posts: 5,510 ✭✭✭✭✭

    @TommyType said:
    Throwing out a WAG, since I have no real knowledge about the time frame we are talking here....

    But would a screw press cause a different flow?

    Part of me likes the idea....the radial direction might be influenced by a slight circular "twist" of the dies...

    But...that same twisting motion would seem to also cause significant "strike doubling", as we call it. Shearing of the design elements...

    Anyway, I'd focus on how the presses and equipment are different than what the US uses??

    Looks like @TommyType had the right idea.

    Donato

    Hobbyist & Collector (not an investor).
    Nolan Ryan Master Set ---- Nolan Ryan Topps Master Set
  • TommyTypeTommyType Posts: 4,357 ✭✭✭✭✭

    @divecchia said:

    @TommyType said:
    Throwing out a WAG, since I have no real knowledge about the time frame we are talking here....

    But would a screw press cause a different flow?

    Part of me likes the idea....the radial direction might be influenced by a slight circular "twist" of the dies...

    But...that same twisting motion would seem to also cause significant "strike doubling", as we call it. Shearing of the design elements...

    Anyway, I'd focus on how the presses and equipment are different than what the US uses??

    Looks like @TommyType had the right idea.

    Donato

    Imagine MY surprise. :neutral:

    :blush:

    Easily distracted Type Collector
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