# Drill a hole in crucible?



## ssharktu17 (Jan 18, 2022)

Hello I am looking to make silver shot or sterling shot. I want to get a large crucible like 20kg and drill a hole in it so I can melt silver continuously and produce shot. Is it possible to drill a crucible or do they need to be designed like that? I dont have the equipment or welding gear to move around a giant crucible so Id like to minimize any of the moving or pouring.


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## Elemental (Jan 18, 2022)

How much shot are you looking to pour at once? A 20kg crucible holds about 2.5L of liquid. My first thought is that this is a bad idea. Perhaps if you attached some sort of sketch showing what you're exactly trying to engineer here, that would be helpful. Where would you put the hole? Are you quenching the shot or dropping it into graphite powder? I think we are going to need a bit more of an explanation of what your trying to do.


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## ssharktu17 (Jan 18, 2022)

Elemental said:


> How much shot are you looking to pour at once? A 20kg crucible holds about 2.5L of liquid. My first thought is that this is a bad idea. Perhaps if you attached some sort of sketch showing what you're exactly trying to engineer here, that would be helpful. Where would you put the hole? Are you quenching the shot or dropping it into graphite powder? I think we are going to need a bit more of an explanation of what your trying to do.


A lot of scrap sterling old flatware sets, bulky type stuff like tea pots or big dishes. Basically just want to put a big crucible in an insulated stainless drum and melt it into sterling shot. I would like to avoid the lifting/pouring and moving part for safety and not having the appropriate tools for that.


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## Elemental (Jan 18, 2022)

Are you trying to do something like this? I think the hardest part would be getting the silver to come out of your hole and into a graphite tube and not solidifying in the tube, you would have to keep the tube heated as well or well insulated with Kaowool. Also, I have no idea how you might control the flow rate.


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## orvi (Jan 18, 2022)

ssharktu17 said:


> A lot of scrap sterling old flatware sets, bulky type stuff like tea pots or big dishes. Basically just want to put a big crucible in an insulated stainless drum and melt it into sterling shot. I would like to avoid the lifting/pouring and moving part for safety and not having the appropriate tools for that.


Not a big professional in the operations like one attempted, but i think it is doable.
20 kg batch would be somewhere 2+ liters of molten metal + some dross/slag. As I imagine the whole process... I do not think you need such a big crucible, but it will be somewhat quicker with larger one=higher area for heat transfer.
As the silver melt, it will flow to the bottom and drain through the hole, so this could be done continously, just adding more raw sterling and harvesting shot in some high and big steel barrel with good water circulation.

"Heat management" with the cooling water should be considered, because cooling down 2 L of molten silver is not a joke  without steam explosions and other accidents.

Many times, crucible is perforated with teeny holes near the top. And as you grab it with tongs and tilt it, molten metal pour through tiny holes at the top to water basin, creating small grains of metal. Nice and even in shape 
For this ammount on regular basis, you should maybe consider some tilting furnance.

Also think if the material of crucible could be drilled - not to develop cracks. Graphite will be OK, but with sintered materials like clay/SiC+clay etc. I will be cautious not to crack expensive stuff  and wreck the drill bit because of hardness of material  but it could be drilled tho, it is brittle and slowly goes through, but cracking is a real issue.

Good luck with project


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## ssharktu17 (Jan 18, 2022)

Elemental said:


> Are you trying to do something like this? I think the hardest part would be getting the silver to come out of your hole and into a graphite tube and not solidifying in the tube, you would have to keep the tube heated as well or well insulated with Kaowool. Also, I have no idea how you might control the flow rate.


Thats pretty close. I was just thinking of having the bottom of the barrel not heavily insulated and cutting a hole in it so the crucible could drip straight down. Im not that concerned with heating efficiency I have a lot of waste oil I can burn.


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## ssharktu17 (Jan 18, 2022)

orvi said:


> Not a big professional in the operations like one attempted, but i think it is doable.
> 20 kg batch would be somewhere 2+ liters of molten metal + some dross/slag. As I imagine the whole process... I do not think you need such a big crucible, but it will be somewhat quicker with larger one=higher area for heat transfer.
> As the silver melt, it will flow to the bottom and drain through the hole, so this could be done continously, just adding more raw sterling and harvesting shot in some high and big steel barrel with good water circulation.
> 
> ...


Ya I suppose it would be a gradual trickle into the water as it slowly melted so I could just add Ice or have a large volume of water circulating. Im not concerned about the look of the of the shot so much as just having it in smaller manageable portions that I can remelt and pour later. Thanks for the info there solid graphite would be the choice.


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## Elemental (Jan 18, 2022)

If you build something, I would appreciate it if you could post some pictures of it and let us know how it works.


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## orvi (Jan 18, 2022)

ssharktu17 said:


> Ya I suppose it would be a gradual trickle into the water as it slowly melted so I could just add Ice or have a large volume of water circulating. Im not concerned about the look of the of the shot so much as just having it in smaller manageable portions that I can remelt and pour later. Thanks for the info there solid graphite would be the choice.


If it will be heated with gas torches or gas/burner in general, graphite would be in turn the most terrible choice :/ I was writing about material suitability to drilling. Resistance to burning is the poorest for graphite.
But it is very soft for drilling and just with bare hand held drill in higher RPM, i doubt you will crack it. But vice is advised for this delicate operation.

Maybe just not scale to 20kg in the first place. Try something smaller, say for 2-3 kilos size, and you will see as things go. Setup isn´t terribly expensive, just a crucible and mineral wool could be somewhat expensive.
You will experience the process in manageable, not so scary scale. And then grow up to the big crucible 

Sreetips was just drilling the classic quartz melting dish and cornflaked his silver like this with hand-held torch quite quickly  

Just be on the safe side and carefully think of every possible scenario and in turn what would you do if something break, crack, fall, spit molten metal etc  
Some U-shaped gutter (maybe with good angle and lubed with water, as sreetips used for cornflaking gold or silver) will be a very good idea to separate the hot molten stuff in the crucible from bulk of water. If it is placed right on top, and steam explosion will occur - the water will splash over 1000°C hot crucible full of molten metal. And this could lead to some very nasty accidents I don´t even wanna think of.


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## jobinyt (Jan 19, 2022)

What could go wrong? Hmmm, seems to me the just melted silver is 'cool' - not much above melt temperature - would easily congeal in your hole if not heated. That would be a minor inconvenience compared to what happens if the crucible fails and dumps with unanticipated rapid nessage into your cooling tank. Unless there a gate on the discharge how are you going to stop the flow if desired? as others have said the problem is just as much 'what if' as it is 'how to'. Be safe.


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## nickvc (Jan 19, 2022)

The norm for shot production is to melt in one crucible and pour that melt into a drilled heated crucible to form your shot , I’m not saying what you are trying to do is impossible but to make it work safely may well be a costly project, you could use a tilting furnace to allow you to pour the molten metal to the next crucible to form your shot but unless you are producing 100s of kilos regularly it seems a little expensive .


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## ssharktu17 (Jan 19, 2022)

orvi said:


> If it will be heated with gas torches or gas/burner in general, graphite would be in turn the most terrible choice :/ I was writing about material suitability to drilling. Resistance to burning is the poorest for graphite.
> But it is very soft for drilling and just with bare hand held drill in higher RPM, i doubt you will crack it. But vice is advised for this delicate operation.
> 
> Maybe just not scale to 20kg in the first place. Try something smaller, say for 2-3 kilos size, and you will see as things go. Setup isn´t terribly expensive, just a crucible and mineral wool could be somewhat expensive.
> ...


I will certainly go slow with it. I will be using waste oil, a steel drum and wool. So it should be easy to reach high temps. I will say there arent many options for large graphite crucibles seems they are all clay-graphite.


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## orvi (Jan 20, 2022)

ssharktu17 said:


> I will certainly go slow with it. I will be using waste oil, a steel drum and wool. So it should be easy to reach high temps. I will say there arent many options for large graphite crucibles seems they are all clay-graphite.


Clay graphite is fine. So is SiC/clay/graphite. These composite ones are somewhat more durable in my opinion and tend to withstand more aggressive fluxes and conditions. Obviously, no crucible is immortal 
But just for melting silver, it should be in service for long time.
These composite ones are more capable with use of the burner. But any material containing graphite will deteriorate over time when hot and placed in air. Thing is, that these crucibles start to burn on the outside and the progress of oxygen to deep insides of the material is quite slow.
I do not personally know how hot this flame could go, but silver is easier to melt than gold. Sterling melts around 900 °C, so it should be fine with complete burning of fuel.


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## goldshark (Jan 21, 2022)

Drilling a hole should be done with a diamond bit with water, Go slow and make sure all water is eliminated prior to use. A variety of bits are available from eBay type stores. I use a drill with a water swivel built in.


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## ssharktu17 (Jan 21, 2022)

goldshark said:


> Drilling a hole should be done with a diamond bit with water, Go slow and make sure all water is eliminated prior to use. A variety of bits are available from eBay type stores. I use a drill with a water swivel built in.


Just like drilling glass makes sense.


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## grainsofgold (Jan 21, 2022)

Nickvc is on point. You would take your molten Ag then pour it slow and steady through another preheated and held hot crucible. Holes are about 1/8 of an inch. the drilled crucible is above a water tank.

I bought a dedicated induction melter made for mixing metal and for graining. But i’ll use it fairly often- made sense for me. 

I also have a picture from lowen that was in an article he wrote fir the Worshipful Society of GoldSmiths. it’s a 55 gallon barrel with several fan type water jets that spray from the top of the water in one side to the other. You pour the molten Ag about 1/3 the way out from the spraying fanned out water streams. Before the water is a slanted baffle. as the silver hits the water it solidifies and roles down the baffle to a a catch can at the bottom of the tank. 

Good luck.


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## Mtntimeearnie (Jan 25, 2022)

If you get a mason bit from hardware store with a drill. Or a dremel with a glass cutting tip should mack you a nice hole


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## jackoa (Jan 31, 2022)

here is a video of my shot pouring setup. works like a charm. if you want small beads, use a small 1/8 drill bit (the crucible will ruin the tip), if you want larger, use a cement bit for blue tapcons.


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## goldshark (Jan 31, 2022)

Lets see it in action please.


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## goldshark (Jan 31, 2022)

Is that a crucible, or a scorifying dish?


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## jackoa (Feb 1, 2022)

goldshark said:


> Lets see it in action please.


You should be able to click on the image and the video will run


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## Elemental (Feb 1, 2022)

goldshark said:


> Lets see it in action please.


If you click on the picture, it should play the video where he walks through his build-out. (Apologies for the repeated message, @jackoa message hadn't popped up when I posted mine)

Elemental


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## cosmetal (Feb 1, 2022)

Let's see it in action along with some pics of your end product.

Thanks!
James


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## jackoa (Feb 1, 2022)

cosmetal said:


> Let's see it in action along with some pics of your end product.
> 
> Thanks!
> James


Currently I have about 10,000grams, this way. You may need a torch to clean out the crucible as you pour the last bits out of the graphite and they solidify before passing through. 

View attachment video (6).mp4


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## cosmetal (Feb 1, 2022)

Sweet! Thanks for the pic and vid.

James


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## ION 47 (Feb 8, 2022)




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## ION 47 (Feb 8, 2022)

ION 47 said:


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