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Noxx

Well-known member
Joined
Feb 24, 2007
Messages
3,365
Location
Quebec, Canada
I know this has been discussed somehow but I still have questions.

Does anyone knows a company making custom metal stamps (dies?) that are made for marking gold or other metals ? I would like to press 10 grams gold bars. I also have access to a 20+ tons press at school.

I don't know much about metal types and such, that's why I'm asking. I don't want anything fancy, only weight (10 g) and Fine Gold markings. The gold ingot shall be in rectangular shape.


Thanks for any inputs !
 
I do it but the outlay was rather pricey. hence why I offer the service but in small denomination of 1/10th rounds.
Although I am finding most people want one ounce pieces instead.
I teamed up with a professional coin die engraver who has a 240 ton press that was an old US mint press. I make the metals, he stamps the coins.
together its been an over all outlay of over $200,000 in equipment to make professional yet still scrutinized due to it being private mint coins as well as a combined effort of over 40 years of combined talent.


My suggestion for small batches, have someone else do it, or buy a $50 stamping hammer set and pray people trust it if you want to market it.

If you want even stampings 20 tones is not enough even on gold to get good results with out spending a lot in machining costs and pray and hope you get enough of an impression. The more area, the more force needed. 20 tones is just barely enough to stamp a 16mm circle. a 10 gram bar will need upwards of 40 to 60 tones to get the correct look of a professional bar, a lot to spend on something that may get $10 over melt.
 
How do you know it will need 40 to 60 tons ? I've been trying to find a formula to calculate it without any success.

Oh and my ingots will be 19.7mm by 13.1mm.

Anyway, thanks for the info.
 
I'm sure your answers are in this book. It is the bible on all things machining. I searched for a while, but it's morning and I've ran out of time...work is calling. I'll look more this afternoon if you havn't already found the answer.

Kevin.

http://books.google.com/books?id=31eWvgTgD7oC&pg=RA2-PA958&lpg=RA2-PA958&dq=machinist+handbook+calculating+press+tonnage&source=web&ots=d1c4J2Et5k&sig=EVLXRCUopK8UHN4MupyVwunmhm0&hl=en&sa=X&oi=book_result&resnum=2&ct=result#PRA1-PA496,M1
 
Thanks for that. I remember seeing that book in a friend's hands. We were looking for a type of steel to use to make my die.
 
I tried to find an appropriate law without any success. When I tried to calculate with Young's modulus, I end up with 1 000 000 kg of force needed, which is, of course, not realistic.
 
I'm not so sure about this, but seeing how soft gold is, this could work?

http://www.harpermfg.com/hm_stamppresses.html?gclid=CPuY4_idopYCFSCcnAod_GOy7A

All it is is a arbor press. You can find one cheaper than this, but the press you already have to work with will do better. This guy is putting his stamp under the press, applying pressure, and then hitting his stamp with a hammer. He's getting pretty nice results from the images shown. A 15 lb sledge hammer in the hands of your average person can deliver about 2 tons of force (according to NatGeo's show "Fight Science") so, figure that down to a 5 lb sledge hammer, and you have about 1,333 lbs of force. This is assuming that the force-to-weight ratio is proportional and that you are swinging it as hard as possible.

I'm still looking for the actual tonnage required, but have found nothing useful as of yet.
 
btw, the company that sells that, Harper Mfg, makes custom stamps. Their pdf shows the different letters and symbols you can choose.

- They have karat stamps that they keep in stock for $10 a piece.
- They have a "Fine Gold" stamp for $17.00
- They have a ".999" stamp for $10.00
- Their custom stamps include many artsy designs to choose from

Something to think about.

I also found out this info.
"STANDARD STOCK STEEL STAMPS
Made on ¼” round heat-treated tool steel.
Size of medium characters is approximately 1mm in height.
Size of the small characters approximately ¾mm in height."


Here's the pdf. http://www.harpermfg.com/HarperJewelryStampCatalog.pdf
 
Interesting, thanks for the info.
But I'll stick to my friend's press.
It can deliver 30 tons. The tonnage is limited by his pump hoses, because they are not rated higher than that. I'm pretty sure his press can reach more than 30 tons, as you can see on the following picture.

If 30 tons is not enough, I could buy higher pressure hoses, his pump can handle it.
 

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viacin said:
I'm not so sure about this, but seeing how soft gold is, this could work? All it is is a arbor press
It won't work for anything but stamping small letters. I used a six ton compound arbor press to imprint my ingots, along with a set of ModelMark stamps, which are assembled in a holder and stamped as a unit, one line at a time.

My logo was approximately 3/4" tall, and looked like the two, below, just smaller. The six ton press was borderline adequate---often requiring the stamp to be impressed more than once to achieve desirable detail.

Harold
 
Noxx, that's a interesting storage shelf. I think it could make a nice press too. That frame could take a whole lot more than 30. This thing makes our 70 ton press at work look tiny. If Harold was using 6 tons, I would think 30 would work, and maybe without having to double stamp like he spoke of. If you didn't mind dinging them up, you can always apply pressure, and then strike the stamp with a hammer to help it imprint better.

Harold, very nice detail on those stamps. You said you sold your business, does that mean Regal Refining is still operating?
 
Looks like a lot of good advise!
Dont forget the science though. Ancient coins and bars
where stamped with a great deal of detail by hand.
many of the early dies where made of stone.
soap stone is easy to carve or ingrave and withstands
extreem temperature.
If the metal is hot enough it only takes a little presure.
Its food for thought any way - you could also look
into sand casting as a way of creating a unique bar.
 
viacin said:
You said you sold your business, does that mean Regal Refining is still operating?
Sorry, I somehow overlooked this question.

No, Regal Refining no longer exists. It was destroyed through ineptness, laziness and being less than forthcoming with the customers. All of the hard work I did in founding the business, which was excellent, was undone in a little more than one year.

Harold
 
slomouse said:
If the metal is hot enough it only takes a little presure.
Are you familiar with the term "hot short"? That's a condition whereby metals lose their ductility when heated. Gold alloys are such a metal. You can not work gold hot----no more than you can work brass hot. It crumbles.

While I was not there to see how ancient coins were made, you can expect that they were not pressed hot.

Harold
 
Harold_V said:
Are you familiar with the term "hot short"? That's a condition whereby metals lose their ductility when heated. Gold alloys are such a metal. You can not work gold hot----no more than you can work brass hot. It crumbles.

that would explain my experience with extremly hot piece of brass that I droped on the floor. It didn't shatter, or even crack, it just crumbled like cast iron. I thouht it was odd.

I'm sorry to hear about Regal Refining Harold. I can't believe someone would screw up such a good thing. It must have been hard watching someone mess up something you had worked so hard to grow and prosper.
 
viacin said:
It must have been hard watching someone mess up something you had worked so hard to grow and prosper.
It wasn't the highlight of my life, for sure. I was very proud of the fact that I created something from nothing, particularly that it was in an area where I had no education. It would have been nice to be able to say I had created the business, and it was thriving. That was my intention.

You can lead a horse to water, but..........

To his credit, the guy paid the debt entirely. I didn't lose any money, but the buyer ended up with equipment and nothing more. He paid the bill over a period of several years. I give him credit for that, but he is bitter because I wouldn't forgive the debt. I saw no reason to do so, for he purchased a good and viable business that had worth far beyond the purchase price.

Luckily, the entire transaction was carried out via an attorney. Everything was well documented, with the transaction registered with the State of Utah. Title to everything didn't transfer until the bill was paid entirely. I'll never know if he paid the debt as a result of the way the transaction was handled, or he was simply an honest man that had no business sense.

I am of the opinion that this individual makes bad decisions, and is the reason he is where he is today (he has not been successful in holding jobs). I gave him excellent guidelines in order to have a smooth transition of ownership. One of the things I advised was that he operate exactly as I did, and to not make any changes until the customers were familiar with him and he had gained their trust. The information fell on deaf ears, as he immediately started second-guessing the operation. The customers abandoned him in short order.

I am anything but a business man, but I was wise enough to provide exactly what the customer desired----having taken the clue from my very first customer, long before I expected that others would use my services.

Harold

edit: deleted a word that made no sense. Content otherwise unchanged.
 
That is sad to hear Harold.

I have always enjoyed looking back on the buildings/projects that I have done for others in the past and see them still enjoying them. There is only 1 business that I started and sold that still exists, and it has been through 2 subsequent owners.

Back to the topic of minting coins… I was splitting wood today for my girlfriend with a hydraulic log splitter of moderate size (27 ton). I thought of this thread and realized it would not be difficult to make an attachment to fit the end of a log splitter that could press coins. With a bit of simple machine work a lever giving a 4 to 1 mechanical advantage could be incorporated giving 100 tons of force applied to the die. Having said that I don’t know how many of you own log splitters.
 
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