homemade anode or ingot molds

[bmgold]

Can steel or stainless steel be used to machine a mold to make anodes or ingot molds if they are well sooted up to prevent the gold/silver/lead etc from sticking to it or is cast iron or graphite the only choices?

 

[Noxx]

Yes, why not ?

But use iron.

 

[bmgold]

Thanks. It figures, I could have gotten steel or even stainless steel from work for free but we don't do much cast iron work. Not really a problem, I stopped on my way home and bought a scrap piece of cast iron that I can use. I also have a piece of graphite electrode material that may make a small, round mold if/when I get enough gold or silver extracted and refined to make a small "coin". I'm still in the learning and gathering of materials and knowledge stage but I see I have passed the newbie stage, at least as far as my title here says. I'm glad to have found this forum and hope to someday be informed enough to add more to the site than just questions.

 

[Harold_V]

Iron is the best choice for a few reasons, although it does not have the resistance to thermal cracking that you'd find in steel or stainless.

The real advantage of iron is its resistance to scaling. If you use a steel mold, it will tend to scale with time, and that's not in your best interest. Stainless might work to satisfaction, but unless it is a free machining grade (303S, 303 Se, or 416), it isn't likely to respond well to machining. Yes, it can be done.

Because stainless does not grow a good oxide coat, it would be easier to solder your metal to the mold, even with a generous covering of soot from an acetylene torch. The problem can be extreme when you pour large ingots, but not nearly as bad with small pieces. I get the idea you're talking about small pours from your comments.

If you make a mold, do keep draft in mind. If you make a straight sided cavity, you may have difficulty removing the ingot. Shoot for at least a couple degrees of draft, with no undercuts to trap the ingot.

Harold

 

[bmgold]

Thanks Harold, I knew someone on this forum would have an answer and yours even had an explanation with it.

As far as ingot molds go, yes, unfortunately I am talking small amounts, possibly 1/10 or 1/4 ounce size. The anode mold would likely be considerably larger. I am still awaiting my order of dvd's from Lazersteve before getting far ahead of my knowledge but am collecting tools and materials to process while I wait.

If the anode is just plain old lead, I expect aluminum should work for the mold but anything hotter and more valuable would need something else to take the heat and not contaminate the ingot with anything or worse yet, contaminate the mold with your gold/silver/etc.

As for the mold draft, I'm thinking a ball endmill should work although it might not make a nice looking ingot, it should be fine for an anode mold.

 

[Harold_V]

As for the mold draft, I'm thinking a ball endmill should work although it might not make a nice looking ingot, it should be fine for an anode mold.

A ball end mill can work, but the ball necessitates that you must take pass after pass to enlarge a cavity. Aside from being slow, it's not a big deal if you have a CNC at your disposal----but on a manual machine it could take a long time, depending on the size of the mold, and how flat you desire the bottom to be.

I used tapered end mills to make all of my molds. They're not expensive, and will serve you well if you use other tools to square the mold, and to rough the cavity before applying one of them.

Be certain you've eliminated the scale from any iron you machine, which you do by taking off no less than 1/8" of the cast surface. It is often contaminated with a little sand, and can also be chilled, making the project less than pleasant. Once you're down to clean gray iron, it machines exceedingly well, assuming it's not chilled. I don't like the dust, but some folks don't seem to mind it at all.

If you elect to buy a tapered end mill, be conscious of the diamter and taper. It stands to reason that if you buy a fairly large diameter cutter, the corner radii in your mold well be quite large. Not bad for large ingots, but not desirable for small ones.

In order to avoid sharp corner on the sides of your ingots or anodes, a slight radius can be ground on the end of the cutting edges, but if you are not a machinist and do not understand cutting technology, I suggest you avoid trying. It's real easy to screw up an end mill so it won't cut. The radius in question will leave a radius along the bottom edges of the mold cavity, while the diameter of the end mill will determine the corner radii.

Hope some of this helps.

Harold

 

[bmgold]

Anyone have some dimensions for a real ingot mold? Down to thousandths of an inch if possible but a general tape measure idea if that is all you have. I expect there is a way to calculate the size if need be. I'll have to check my copy of machineries handbook at work.

I'll also check on the tapered end mill at work and maybe have them slip one into their tool order to avoid shipping costs.

I do have access to cnc equipment but want to save that "favor" for a more involved job someday. It is used a lot so getting use of it would be a little tough. You can't tear down a paying job to make your own stuff. Manual machines should do.

 

[Lou]

There's a way to calculate the volume needed, but it's better to simply melt the requisite amount of gold.

Density=mass/volume. So if you know how much your bar should weigh, and the density of liquid gold at 2200F (CRC has it), then you can easily solve for the volume.

Still easier just to mass it out and cast it into a mold that has a little head room.


Lou

 

[Harold_V]

Still easier just to mass it out and cast it into a mold that has a little head room.

That doesn't work in all cases. Because of gold's desire to ball up, if you try for an ounce ingot in a two ounce mold, you end up with an incomplete casting. It is for that reason that my molds were made in various sizes, although I also was concerned with aesthetics.

My half ounce ingot was really cool----like a tiny loaf of bread. It would not pour in an ounce mold, no matter how hard I tried.

Needless to say, large ingots are far more forgiving. My mold size jumped from five to ten ounces. I had a five, three, two, one, and a half.

Harold

 

[bmgold]

Thanks for the replies. Wow!!! 5 and 10 ounces is way beyond even MY wildest dreams at this time. I'm thinking more like 1/10th ounce or possibly 1/2 if I dream a bit. I wasn't thinking right. You couldn't just fill the mold or pour to a line and expect the weight to be close enough when dealing with $700+ per ounce gold.

I checked on tapered end mills and while not real expensive for the small sizes, the price jumps considerably when you go to larger sizes. Since I don't have enough gold to worry about needing a mold yet I may just wait before purchasing or building a mold. Still may try to build a mold for an anode or cathode to use in a cell of some sort or just to play with some lead or even silver to test things out.

After getting and watching Lazersteve's dvd's I now realize that nitric acid looks a little more dangerous than I hoped it would be. Even the 1/2 gallon or so batch of HCl/bleach looked a bit dangerous. I also saw the quantities of scrap involved to get a small piece of gold. I have to collect and separate way more scrap before attempting the extracting and refining. The education from watching the videos was well worth the cost of them and I hope he keeps making more videos. I'd say that all newbies and anyone thinking about getting into this refining hobby or business should watch his videos either online (If you have a fast connection...45 kbps just won't do it here) or buy the dvd's. Sorry to sound like an advertisement but I'm a happy customer. Thanks Steve.

By the way, in the video I didn't notice the fumes when the bottle of HCl was opened up. Maybe mine is stronger or maybe it has some contaminates or maybe the video just didn't show it up but mine fumes when the lid is opened. I can't imagine pouring 1/2 a gallon into a container at a time without some real good ventilation.

 

[Harold_V]

Thanks for the replies. Wow!!! 5 and 10 ounces is way beyond even MY wildest dreams at this time. I'm thinking more like 1/10th ounce or possibly 1/2 if I dream a bit.

You will have little success attempting to pour small amounts of gold. It is for that reason that small ingots tend to be stamped, not cast. One of the problems is getting all of the gold to leave the melting vessel and end up in the ingot. By rolling gold to a specific thickness, planchets can them be punched, adjusted if necessary, then stamped at a specific weight. Unless you intend to get in the medal business, it's not likely you'd want to get involved with those processes, if for no other reason, the economics involved.

Since I don't have enough gold to worry about needing a mold yet I may just wait before purchasing or building a mold. Still may try to build a mold for an anode or cathode to use in a cell of some sort or just to play with some lead or even silver to test things out.

Fact is, you can melt gold in a melting dish and achieve quite good results. You don't have to pour, it can be left in the dish to solidify, at which time it can be removed easily with a tweezers. If the flux coating in the dish sets, the button will be glued to the dish, so the window of opportunity to get it removed is short. I returned gold to my customers in that fashion for several years, until I finally started pouring shot.

Buttons retrieved from the melting dish, as I described, often have a small coating of borax. It can be removed by boiling the button in a small vessel with dilute sulfuric acid.

Sorry to sound like an advertisement but I'm a happy customer. Thanks Steve.

Steve deserves any and all praise that you can provide. He has worked hard to provide readers with good and useful information. Readers of this forum would be lost without his expertise.

I can't imagine pouring 1/2 a gallon into a container at a time without some real good ventilation.

Think fume hood. Of all the acids you'll handle in the course of refining precious metals, it's entirely possible that HCl is the worst offender where your lungs are concerned. Working in the mouth of an adequate fume hood eliminates any and all problems.

Harold

 

[bmgold]

I just finished building a mold to pour lead into to make an electrode for some type of cell. I think it may actually be used as the cathode but it did pour ok. It took a lot of hand filing to get enough draft for the part to come out but it looks like it would work.

After reading the replies and lots of other posts I think, for the small amounts I would get, I will just stick to the button idea and give up on ingot molds at least for now.

I now need to study the different cell designs to see if I could build/use such a thing.

I am eagerly awaiting any more dvd's from Lazersteve since even with high speed internet now, I still can't get the videos on his site to work. I expect I need an updated video player or something.

If lazersteve is reading this, I would be interested in buying a copy of the cell videos on cd or dvd for computer viewing only if you might be talked into such a deal. I know how much time you must spend to make the videos into a dvd version. I'd probably get a little tin from you and maybe a melting dish if it would all fit and make it in one piece in the one price shipping package. PM me if you might be interested in such a sale. If not, no problem. Keep up the good work on the dvd's. I will most likely buy more when they are done.

EDITED AGAIN: got the videos to work online... still interested in an offline copy but not needed. Great videos. THANKS

Thanks everyone. The picture is my mold for the electrode and a couple castings of lead. The quarter is to show the size and the dark stain is some plated copper from a quick test I did. The electrodes can be put into a small glass candle holder I got at the dollar store. They can be bent over the side or just hung from a paint stirring stick or other non-conductive holder placed on the top of the glass container.

Edited: The mold is made from aluminum but works so far for lead. When I get a small stripping cell completed I'll post a picture of it.

 

[bmgold]

I finally got Lazersteve's online videos to work and his melting video was a great inspiration (especially the mold). Maybe he can be talked into posting a picture of the resulting gold bar.

Edited to keep from making this topic to long (I'm already an active member...Don't need to increase my message count)

Thanks for the picture Lazersteve. It looks good. I'd be happy with one a fraction of that size. Maybe someday.

 

[lazersteve]

Bmgold,

Here's the 37 gram bar right out of the mold.

[img:716:457]http://www.goldrecovery.us/images/molded_bar.jpg[/img]

Steve

 

[bmgold]

I just got a mold that should work as an ingot mold. It was a die to form lead for a job we had at work. It was made from hardened tool steel and had a rounded shape burned in with an EDM at another shop. I tested it with some lead and it made an ingot that weighed 3 troy ounces. It is larger than I wanted but it was free since it had a defect in it. My quick calculations are that it should make a 2 ounce silver ingot or about 5 ounces of gold. I might have this wrong but those are the figures I came up with going with the specific gravity of lead, silver and gold. The mold would not have to be filled to the top to get a nice ingot since the bottom is rounded and tappers to the top. Looks like a miniature belt buckle.

 

[rainmaker]

Just a note on using iron molds. I have an old lead bar sinker mold made out of cast. I have been using a single application of graphite grease for a long time, many pours. It iis available from the auto parts store. I burned the first and only application in with my propane torch prior to the first use.

 

[bmgold]

Thanks for the graphite hint. I expect you are talking about graphite lock lubricant. I'm not sure it would burn into my hardened mold like it would with cast iron so it would probably have to be reapplied more often. I might be wrong about this. I just carboned up the mold with an acetylene torch and that worked so far with lead. I plan on trying it with some sterling silver scrap to condense all the broken chains and bent rings I have collected. I just ordered a small sand casting kit to try to make some trinkets or maybe a ring or something. I also want to try casting some parts for a model steam engine but not from silver or gold. I'm thinking aluminum or pot metal. Pot metal would be easier to cast and would probably be better for the flywheel but it's not much fun to machine (sticks to the endmill or lathe tool). Brass might be an option that would make a nice engine but I've never tried casting it. Maybe a little borax as a flux?

 

[GeeDub]

We ghetto refiners are sort of like Hill Billy refiners. At least when we start out. Here are 2 things I used long ago.

1) if the smoothness and finish isn't that important, for those really small 1/10th ouncers, I used to just carve one out of the other side of the charcoal block I used to solder jewelry.

2) For larger buttons, I used a cast iron muffin pan bought at a housewares store. Just greased it with a little motor oil. Nowadays motor oil has too many additives, so I would suggest vegetable cooking oil from the supermarket. Poured all my gold and silver as muffin ingots until I started selling to casters, who wanted shot.

 

[bmgold]

I just finished making a couple pretty simple graphite molds and tested them out with some lead.

The small rectangular one was made out of a scrap of EDM electrode material using a small ball end mill. I figure it should make about a quarter ounce bar of gold (If I had some ) It is a little bit hard to pour that small of quantity without over-filling the little mold. It should work when only dealing with a small amount to pour like 1/4 ounce.

The round one was much easier to make using a small lathe and a 1" diameter piece of graphite. This stuff is dirty and dusty to machine but it does machine pretty easy. I used a small end mill held in the drill chuck of the lathe to bore it out to about the depth needed and then, with a small boring bar, I cut a small taper on the sides. This mold should make about an ounce round ingot if it was bored a little deeper.

I can't say how they will work with gold or silver yet but, they both work real nice with lead. The little ingots fall right out when it is turned over. I'm surprised more people don't use round molds or at least I haven't notice any pictures posted here. A lot of people have small lathes in their garage or basement and I expect that with some care someone could hand carve/scratch a design into the bottom of the mold and get a unique ingot/token poured. The lines left from facing the bottom of the bore transfered to the casting and in the rectangular mold, I carved away a little lump left in the bottom from using a ball end mill and the scratch marks showed on the cast bar.

 

[nicknitro]

Hey BMGold,

Just a suggestion, I meant to post it on your othe topic, if you are melting things in your melting dish, that are not know to be gold, don't reuse this dish for gold, it could contaminate your final nuggets, and the most probable solution to getting it pure again would be inquartation, then re-refining from scratch.

Seems I remember you tried E-Bay gold flakes& Pieces, most likely copper, zinc, and other non PM's.

Good Luck,
Nick