{"id":5377,"date":"2017-07-23T14:23:02","date_gmt":"2017-07-23T21:23:02","guid":{"rendered":"http:\/\/sterlingsculptures.com\/wp\/?p=5377"},"modified":"2017-07-23T21:25:55","modified_gmt":"2017-07-24T04:25:55","slug":"knapadonia-challenge-coin-tutorial","status":"publish","type":"post","link":"http:\/\/sterlingsculptures.com\/wp\/?p=5377","title":{"rendered":"Knapadonia Challenge Coin Tutorial"},"content":{"rendered":"

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\n<\/a>I’m curious to see if I can make this work: a coining die so I can create small copper challenge coins in my little 20 ton press. Every year, I try to create an art object as a fundraising opportunity for a local knapping group I attend. August is our annual \u201cknap-in\u201d at Knapadonia, located on the North end of Whidbey Island, near Seattle. Hopefully these little challenge coins will raise funds for \u201cKrapadonia\u201d – the porta-potties we rent for the attendees.
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Here’s the start of creating a CNC’d coin die out of 12L14 Ledloy steel. I\u2019ve chosen this particular steel because it will machine well in my tiny little Nomad 883 desktop CNC mill, and because I have it on hand in the correct diameter. As so many have pointed out in my Facebook and Instagram posts, yes, harden-able tool steel would make a better, longer lasting die. Also, as several have pointed out with the authority of experts, that my tiny 20 ton press won\u2019t work, that a 100 ton press would be the smallest that would be capable of such a feat. Now , with the hindsight of having done the \u201cimpossible,\u201d I\u2019ve rediscovered what I learned so many times before. It seems I\u2019ve spent my life accomplishing the impossible, only to find out that I\u2019m not particularly extraordinary, just that \u201cimpossible\u201d is simply the state of someone else\u2019s mind. I\u2019ve also found that a closed mind and an open mouth seem to be natural partners\u2026<\/p>\n

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\nAbove are the Ledloy steel blank, with the center point already located and marked, along with some blue painter\u2019s tape and some copper wire for wrapping.<\/p>\n

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\nThe blue painter’s tape creates a little well for containing a puddle of coolant. I wrap the copper wire around the base of the painter\u2019s tape in case the coolant I\u2019ll use (WD-40\u2122) decides to attack the glue of the tape. Have I mentioned I\u2019m a belt and suspenders kind of guy?<\/p>\n

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\nHere\u2019s the die blank installed in the CNC mill, with a small puddle of coolant. Below are the Feeds and Speeds I used for milling the steel die.
\nNomad 883 Feeds and Speeds (mild steel)
\n<\/b>RPM \u00a0 \u00a0\u00a0<\/b>Depth of Cut \u00a0 \u00a0\u00a0<\/b>Feed \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0<\/b>Plunge
\n<\/b>8800 \u00a0 \u00a0 \u00a00.002 inches\u00a0 \u00a0 \u00a0 \u00a0 3.0 inches\/min\u00a0 \u00a0 \u00a01.0\u00a0inches\/min<\/p>\n

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\nOf course, the die isn\u2019t the only bits I\u2019ll need to pull this off. I\u2019ll also need a flat faced steel pusher and a large tube to keep the pusher, copper coin blank and die all aligned while I apply 20 tons (40,000 pounds per square inch) of pressure.<\/p>\n

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\nAbove are the completed steel die, aluminum alignment tube and flat faced steel pusher.<\/p>\n

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\nHere\u2019s how the parts go together\u2026<\/p>\n

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\nAbove is the first pressing from the challenge coin die. I had a 3\/4″ circle of 1\/4″ thick annealed tellurium copper for the first attempt. I’m going to call this one a failure…while it looks good <\/p>\n

Buy Provigil Without Prescription<\/a><\/div>\n

, it took 7 or 8 annealings and 20 ton pressings to get a complete impression. Too much work, so I’ll make another shallower die and try again.<\/p>\n

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\nAbove is a closer view of the first pressing.<\/p>\n

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\nAbove is the new die with a shallower arrowhead milled into the surface , hopefully to take fewer pressings to obtain a good impression. I\u2019ve also engraved the lettering around the edges. BUT, oops\u2026do you see the problem? Talked myself into it, out of it, and into it again. That’s what I get for doing critical work when I’m tired\u2026<\/p>\n

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\nAbove, I\u2019m using my Lindsay Palm Control Airgraver<\/a> to hand engrave the lettering for the coin.<\/p>\n

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\nAbove, the resulting copper coin after just 2 pressings and annealings. I’ll take that – time to make the lettering for the back and start production\u2026 It kind of looks like an ancient Greek coin with the backward lettering\u2026<\/p>\n

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\nSo, I lathe-turned away the lettering, at the same time making the arrowhead a little shallower – probably a good thing! Above, I\u2019m engraving the new lettering, properly mirror-imaged on the coin die this time.<\/p>\n

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\nAbove is the completed coin die, with mirrored lettering. Much better\u2026<\/p>\n

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\nHere\u2019s the first pressing with the corrected coining die. Only two pressings and annealings, and a good impression.<\/p>\n

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\nHere’s the production version of the Knapadonia Challenge Coin die system, with all the bits and bobs of the die system. In order to get by with the smaller press and multiple pressings, I needed two different steel pusher cylinders. There was no problem re-indexing the front face (arrowhead) of the coin after the first pressing, but I didn\u2019t have much faith that I would be able to index the reverse side die, so I made the first pressing with the blank faced steel pusher, then re-annealed the coin and used the engraved “not all who wander” steel pusher for the second pressing. I also made the first pressing while the copper coin was red hot with the smooth pusher.<\/p>\n

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\nAbove, engraving the “not all who wander\u201d lettering for the reverse of the coin.<\/p>\n

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\nThe completed “not all who wander\u201d pusher.<\/p>\n

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\nAbove are 4 views of the first coin. I wanted these to look like ancient Roman or Greek coins, and I think I achieved that\u2026<\/p>\n

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\nSo, now it\u2019s time to begin coin production. I weighed out multiple bits of clean scrap copper, approximately 0.4 ounces each. I determined the quantity by weighing the original tellurium copper scrap blank that just happened to turn out about perfect. A blind-squirrel moment for me (even a blind squirrel finds a nut once in a while)!<\/p>\n

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\nAbove I\u2019m using an oxyacetylene torch to melt the scrap copper into a (mostly) round blob, then into the pickle for quench and copper skin oxide removal. Don\u2019t forget to use your proper light filter googles – the acetylene flame is dangerously bright and can burn your eyes.<\/p>\n

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\nAbove is the first batch of copper blobs, ready to hammer (somewhat) flat on the anvil.<\/p>\n

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\nHere they are after hammering flat. I test each one agains the aluminum alignment tube to make certain they aren\u2019t to large in any dimension to fit inside the tube. Finding out they’re too big while glowing hot isn\u2019t the best of times to try and adjust their diameter\u2026<\/p>\n

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\nAbove, the first few completed, along with a few silver challenge coins \u2018cause I can\u2026<\/p>\n

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\nThe Knapadonia Challenge Coins are complete. Most copper, a few in silver. It took two pressings each in a 20 ton press to get a full impression. They kind of look like I just dug up a hoard of ancient Roman coins. Turns out the impossible isn\u2019t impossible if you understand a little metallurgy and use a bit of ingenuity\u2026<\/p>\n

Thanks for Looking!<\/strong><\/p>\n

Tom Sterling<\/strong><\/p>\n

http:\/\/www.sterlingsculptures.com
\nhttp:\/\/www.facebook.com\/TomSterlingHandEngraving#<\/a>
\nhttp:\/\/instagram.com\/tom_sterling_hand_engraving<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

I’m curious to see if I can make this work: a coining die so I can create small copper challenge coins in my little 20 ton press. Every year, I try to create an art object as a fundraising opportunity … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":"","jetpack_publicize_message":"","jetpack_is_tweetstorm":false,"jetpack_publicize_feature_enabled":true},"categories":[50,43,35],"tags":[51,53,3,7,17,16,52,45,21,54,44],"jetpack_featured_media_url":"","jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p6qLAy-1oJ","jetpack-related-posts":[{"id":5101,"url":"http:\/\/sterlingsculptures.com\/wp\/?p=5101","url_meta":{"origin":5377,"position":0},"title":"Combined CNC and Hand Engraving on a Hobo Silver Dollar with Handprint Skull","date":"June 10, 2017","format":false,"excerpt":"After a few successes with wood Pharmacie Montignac Dordogne Pharmacie de la V\u00c3\u00a9z\u00c3\u00a8re , moose antler and brass it\u2019s time for something a little more challenging. There have been a few technical glitches and broken end mills along the way, but I\u2019m confident enough I\u2019ll risk a $20 silver dollar\u2026","rel":"","context":"In "Carving"","img":{"alt_text":"","src":"https:\/\/i0.wp.com\/sterlingsculptures.com\/wp\/wp-content\/uploads\/2017\/06\/Silver_Dollar_Handprint_Skull_Tutorial_17-1.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":6040,"url":"http:\/\/sterlingsculptures.com\/wp\/?p=6040","url_meta":{"origin":5377,"position":1},"title":"Tom’s Interview with The Maker’s Garage – Carbide3D","date":"March 29, 2022","format":false,"excerpt":"Check out Tom\u2019s podcast interview with Kevin Barnett of Carbide3D - The Maker\u2019s Garage! Hear Tom\u2019s words of wisdom and deep artistic philosophy about CNC and engraving\u2026amaze your friends! Mention that at any coffee shop Kup Lasix bez recepty , hand them ten dollars and you can get a really\u2026","rel":"","context":"In "Carving"","img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":5565,"url":"http:\/\/sterlingsculptures.com\/wp\/?p=5565","url_meta":{"origin":5377,"position":2},"title":"Dragonfly Hobo Nickel Tutorial","date":"May 29, 2018","format":false,"excerpt":"I need a little timeout from the hummingbird skull reliquary puttygen.in , so here\u2019s the start of a fun Hobo Nickel with a gold dragonfly. I\u2019m leveling out Jefferson\u2019s head with a punch and abrasive stones, and beginning the engraving. Inlaying a 24 karat gold dragonfly in a Hobo Nickel.\u2026","rel":"","context":"In "Hand Engraving"","img":{"alt_text":"","src":"https:\/\/i2.wp.com\/sterlingsculptures.com\/wp\/wp-content\/uploads\/2018\/05\/TomSterling_Dragonfly_Hobo_Nickel_Tutorial_7.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":3636,"url":"http:\/\/sterlingsculptures.com\/wp\/?p=3636","url_meta":{"origin":5377,"position":3},"title":"Skull and Centipede Hobo Nickel","date":"November 17, 2014","format":false,"excerpt":"Back to engraving with a Hobo Nickel project, just for me. This is my first solo Hobo Nickel, with\u00a024 karat gold centipede legs, moose antler zombie eye. Here\u2019s my design transferred onto a 1937 buffalo nickel. Don\u2019t know what a Hobo Nickel is? \u00a0Try hobonickels.org Above is the design engraved,\u2026","rel":"","context":"In "Carving"","img":{"alt_text":"","src":"https:\/\/i0.wp.com\/sterlingsculptures.com\/wp\/wp-content\/uploads\/2014\/11\/Skull_Centipede_Hobo_Nickel_16.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":3682,"url":"http:\/\/sterlingsculptures.com\/wp\/?p=3682","url_meta":{"origin":5377,"position":4},"title":"“Greenman in Autumn” Pendant Dagger, Part 2","date":"December 24, 2014","format":false,"excerpt":"I started the engraving by cutting all the major lines. Next I'll inlay gold wire into the Celtic beard... Inlaying gold wire, from top left clockwise - undercutting the line (blue arrows) - hammering in wire - more hammering - all wire in place Clockwise from upper left - scraping\u2026","rel":"","context":"In "Carving"","img":{"alt_text":"","src":"https:\/\/i1.wp.com\/sterlingsculptures.com\/wp\/wp-content\/uploads\/2014\/12\/Pendant_Dagger_121.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":4129,"url":"http:\/\/sterlingsculptures.com\/wp\/?p=4129","url_meta":{"origin":5377,"position":5},"title":"Inlaid Shibuichi “Slimy Snail” Hobo Nickel Tutorial","date":"January 3, 2016","format":false,"excerpt":"Starting a new project, a Hobo Nickel with a shibuichi Japanese-style snail inlay. 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