Topic: Question to collectors regarding metal content/weight (Read 577 times)

Hi,

Yes, the clay is expensive. Needs air vents, it's to compact. But good stuff for simple shapes.
We tried closed casting without air vents. Poor results. Open casting seemed promising as an alternative to graphite molds (with us of 'needle' hole venting').  

Yes, the results are inconsistent, so we stick with simple geometric shapes and the logo. Can do some more details, but result will always vary.
Yes, if a detail breaks, start over again...
Resin 3D printers are the best, we use them, are experimenting with wax as well, near perfect detail.
But seems you already have experience with most methods, cool stuff you are making!

Example of our venting:

    

Good luck, am interested in a spoon or fork...
.925 would be best in my opinion, stronger. If possible use rhodium for finishing gilt layer, would be cool and shiny + somewhat scratch resistent.

Pyrite, in layman's terms, is fools gold (some pun intended).

I use Petrobond for less expensive metals like copper and brass when I have the patience to hand finish things or lose detail. I've never used Delft Clay because of the cost. Do you bother cutting vent holes when you use delf clay/green scand/ or petrobond? Ive had pretty decent luck just using the porosity of the material itself. What I really do not like about the sand casting methods, is 3D models with lettering are realllllly inconsistent if you do any sort of lettering or detail where you can break the sand and remove features when removing the model. I had issues where if I applied inconsistent pressure when packing, sometimes I could remove the 3D model, sometimes I couldn't, etc. If I pack too hard vs not hard enough even if I didn't break features off, I'd get inconsistent weights as well which is really tough with this crowd.

I've not used pyrite before, but I'll look into it. I primarily use gold, electrum, argentium silver, fine silver, aluminum bronzes, copper, aluminum, platinum/palladium (though I need to retool to do those better) though I've tried a few exotics with mixed results. Purple gold is by far my favorite but the strangest material I've ever worked with. Its super pretty but has  trash mechanical properties. This is a stock photo from google pictures, as I don't have any pictures of what I've made with it handy.




The primary method I use now is lost wax casting. I've got a Resin 3D printer which is slow as hell but produces unbelievable detail down to a couple of microns. I can buy castable resin for it and go straight from print to mold, but the resin is something like $375 per liter, so I just use the standard stuff that'll provide me with a good finish, and put it in a silicone mold so I can wax inject replicas. Material cost is still sort of ridiculously high for low batch things, but its a lot better than adding up all of the man hours that goes into making things individually.

With the spoon and about 50 other plans I have, the issue I am running into is my furnace size for burning out the molds. Its taken forever but I'm finally getting around to finishing up my 13.5x13.5x13.5 inch kiln. Ive just gotta make some finishing touches and install the electronic controls at this point and I should be all set.



Plaster casts are typically 1 time use, but they give the best detail. Commercial products have all sorts of chemical additives to eliminate air bubbles, (though you still need a vacuum chamber) surfactants to keep the surface of the molds super smooth and without pores otherwise you get pits in your cast, and low shrinkage factors. DIY methods will work if you are careful and do a carefully controlled heat cycle to remove ALL moisture from the mold, but often the size of what you cast will be inconsistent at the very least.

I use commercial investment powders, and while expensive, give expected results more often than not once you deal with a few minor tweaks that you'll need to do regardless of mold material. The burnout cycles are provided by manufacturers, and typically take anywhere from 10 to 18 hours with VERY specific temperature heat soak/ramp schedules. They might require you start at 275 degrees (Fahrenheit) for 45 minutes, ramp up to 350 for 30 minutes, then up to 475 for 15 minutes, 550 for 2 hours, 675 for 3 hours, 900 for 2 hours, 1150 for 2 hours, 1350 for 1 hour, and then back down to 900 before you cast the material. Little things like not following the very particular timing/length can completely ruin an otherwise perfect mold. DIY products don't have manufacturer suggested times, so just know you'll have to do a bit of experimentation before you get it right.

Going to make this post even longer and just throw in a few pictures of things I'm working on.







And to physically hurt the bullion collectors here

Very cool spoon!

Casting in Green sand, Petrobond or (Delft) clay is indeed less suited for detail and a smooth surface finish. And cumbersome with regard to finish, but a great entry point for casting.  
Will say Delft Clay is best of choice in my experience, more oil in the substance, better cohesion and clearance of model.
Air venting en flow of silver is where we learned the most. Also, heating the clay a bit before pouring seemed to help (but not to much, because of the release of oil when heating).
Have tried a couple of models with detail, but best do detail with lost wax as you mentioned.  
We have been playing with Braluminium, alloy of bronze and aluminium. While not suited for collectibles, nor precious, good stuff!

Thanks for the inspirational post and valuable comments of others.
Maybe a Pyrite version of the spoon for BCH? (though Pyrite is brittle, and toxic when heated)

I did see refractory concrete breaks up after water vaporizes most of the times, I did see some nice molds of that concrete that done pretty well tho maybe making the mixture properly and the brand you use influences but that takes a bit of trial and default i guess.

On the other hand it can't be more than two days that I discovered stone for this purpose, however in past experiences with stone and fire stone can break up and no idea how'd I could carve there.

Thanks a lot for the encouragement, should of answered way earlier but even looking specificaly for this thread I saw nothing in new replies.

I appreciate it. It was serious, but I should be in the clear now. I'd be careful with refractory cements, they really don't handle temperature changes well and aren't designed to rid themselves of moisture to the degree that needs to be done. In the best case scenario and you are lucky and it holds up, your surface finish will likely have issues. As I've found through the years, the difference between the expensive method of metal product production where you use professional products versus the DIY homemade versions is success rate and time. Home made versions fail more often and require a lot of extra manual work to get to a finished product, which by the time you are done with it replaces the cheaper DIY material cost with labor costs.

Titanium is neat, if just sort of blows up if you heat it improperly. I've got a lot of neat and interesting metals I can work with though. I say go for it with the 1 KG copper coins, just a heads up though it'll likely take you a while to get it right. Copper is really hard to work with, its taken me about 5 years to cast my own copper pan and I'm close but still haven't gotten it quite right. Its doable, just requires a whole lot of tinkering, degassing, temperature, and geometry exploration. Best of luck 

Hope you get better and it nothing serious.
Lol the 0.05% goldspoon chance id do it if i could.

So I has quite a while wanting to do some melting and pouring myself, I haven't found much information but my idea is using refractory concrete as mold, as far as I seen in a vid if you careful you can even use it more than once.

I like titanium but I heard its a pain in the arse without argon atmosphere. You could perhaps make a collection of different metals.
Spoon bullion lol.

PS: I plan making 1 kg copper coins as start, 51 of them, with 5 spots for holo and 5 coins on the front , featuring BTC ETH XMR XML and STEEM, however i first thought of doge instead of steem, just can't fit all coins i like .

The project isn't dead, just had some health issues come up a little while ago that prevents me from executing all of my fun project plans. I'll be back at it in April though!

To save other people the googling time:


-Dave

Platinum I can do, zirconium I have no idea at the moment but I can look into it, and Tungsten isn't workable with heat. It has the the highest melting point of any metal (6200F / 3420C) and I believe rather than being melted to combine multiple bits of tungsten together, its sintered.

The mention of the gold spoon was 99.95% a joke by the way.

Platinum? It's less expensive then gold but it does have a much higher melting point so the actual making of the spoon would be more difficult.

I have always thought it would be neat to have some stuff with "oddball" metals.
Zirconium is light so it would be weird to have a what looks like a standard thing but it is much lighter.
Tungsten would also be cool.

-Dave
 

You know... Id be quite an interested buyer of that spoon.

Change "hold" to "hodl" and maybe hologram it. That would be an awesome collectors piece.

Sandcasting with precious metals can be a bit sketchy. In the absolute best case scenario, the surface finish is just not fantastic and you lose a lot of detail. In the not that bad but still frustrating cases, you'll just get a ton of failures for each success. Even assuming the best case, you end up doing a ton of grinding and finish work which ends up more expensive by the time you are done due to the required man hours. I typically use the lost wax method using 3D printed Resin model, a high quality investment powder (casting plaster), vacuum pumps, and metal. The setup and material costs are higher than sandcasting, but the method allows far more intricate detailing and requires much less time to get a finished product.

Right now the issue I ran into is that my kiln is too small. The ceiling height can't accommodate a flask large enough to fit a spoon into it, so I'm building a new kiln. The fire bricks arrived broken, still waiting for the heating elements and control panel parts to come, and then I've got to assemble the thing.  

i have not cast any metal since the 1970’s in high school foundry shop.

making a sand mold was time consuming. and i had a lot of failed casted items.

but i figured i could ask i some one else got you up to 2000.

here is a merit to go to 2001

I can, but I've pretty much found out that in most cases, making single order custom things is prohibitively expensive.

I am on the cell pushed you to 1999 with the last merit this account has. I have a pewter letter opener any chance you could copy it in sterling? My location is nj I could photo the letter opener. Next to a ruler .

I'm not geared up properly to handle ferrous based metals right now, but if I get into forging so I can make meteorite kitchen knives that could be neat, though I don't know exactly how usable they'd be. I'll do some searching around for something interesting while I'm waiting for all of my kiln materials to show up. Francium spoon!

On a side note, I've got a ton of plans and partial designs for things that aren't spoons with different purposes in different materials. I just got on a kitchen utensil kick recently and decided I wanted at least one silver spoon/fork/knife for when I want to feel fancy eating a bowl of cereal. I've successfully made custom rings with Bitcoin private keys inside so you can have a backup and discrete way to carry your coins on you. A few decisions need to be made about whether I just ask people to encrypt and send me the keys to put on them, or if I could obscure the inside and make denominations of wearable keys. I've got a few solutions for obscuring the keys though they wouldn't be perfectly foolproof as a jeweler may be able to figure out what I'm doing and redeem the BTC. For a self funded model of course you don't have to worry about it trading hands so its not a concern.

I has no idea what to suggest, last time I were searching metals i ended up in radioactivity and discovered europium which just tarnishes very fast even looks very nice if properly protected.

Long ago I were really interested in seeing a physical made of meteorite metal, which is expensive as hell and I think it is not pourable since youd lose the etching pattern.
Edit: I found these things at arizonaskiesmeteorites.com
And just noted they just got quiiite a few new specimens.

Exotics are fun but hard to source and are often full of surprises. That said, if you have a suggestion I'm all ears and I'll at the very least look into it and give you a proper response as to why its a good or bad idea.

I picked silver first because besides being my forte, its actually a suitable material for dining ware. Making this spoon out of gold is really a pipe dream, I mean I could do it, but it'd be something like 4 oz of pure gold or ~0.8 BTC just in metal. Not really that great of an idea.

Ugh I never imagined I'll never get more merit to give.

Gold would be a bit expensive, why you don't try some exotic metals that ain't as expensive.

I've got a general idea of the direction to take, but still looking for input while I wait. The spoons are just long enough that they don't fit in my kiln now and I'm not changing the length as I find them very properly sized, so I'm building a new kiln. While I'm waiting for all of the bits to arrive, please feel free to keep the suggestions/opinions coming in.

My plan as of right now is to make two versions, one in .999 silver and one in Britannia Argentium silver. I expect they'll both be damn near 2 troy ounces, but I won't know exactly until I have them made. Not sure yet whether I'll mark 2 Troy Oz Fine silver on the .999 version if they do indeed remain above but ~ 62.2g of silver after finishing.

I sort of want to make a gold one as well, but I feel like that'd be kind of stupid...