Sand casting unobtainium parts at home.

So hypothetically, if I were to do a casting which required 27 litres of molten aluminium it would take some manhandling at 72.8 kg and I would be calling on able-bodied Froggers to lend a hand at the crucible. Best you start weight training Jaahn, there's a challenge back..


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Well, who'd have thought that the atomic weight of aluminium is 27! (That comes from the number of moles of Al in 27 litres). Or that 27 litres of Al is 5,400 metric teaspoons. What a great table. Love it!

I think you need a tilting device.....
 
This looks like a fairly simple device except I don't like the position of the yellow feed wheel because the operator will not have a straight line of sight to the business end, the idea being to pour straight from the crucible/furnace into the mold. It might be time to get the drawing board out and design my own version :unsure:

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Agreed - I like the worm drive part of it for the obvious reasons of control.
 
Yes, control is very important as is the flow rate. The entire contents of the crucible will need to be poured in in a controlled fashion (not to slow and not too fast) in about 20 seconds. Target accuracy is also important, it all happens very quickly.
 
56 Fregate said:
Yes, control is very important as is the flow rate. The entire contents of the crucible will need to be poured in in a controlled fashion (not to slow and not too fast) in about 20 seconds. Target accuracy is also important, it all happens very quickly.
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I can imagine that. I look at people doing this with leather apron, a sound approach. But any video I've watched made me wonder about foot and lower leg safety. A bit of splashing wouldn't be fun.
 
JohnW said:
I can imagine that. I look at people doing this with leather apron, a sound approach. But any video I've watched made me wonder about foot and lower leg safety. A bit of splashing wouldn't be fun.
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Meanwhile in Armenia.....

www.dailymail.co.uk

Man puts his BARE HAND straight through fiery molten ore

Is this skill or madness? In this remarkable footage an Armenian foundry worker can be seen putting his hand straight through boiling hot molten metal.
www.dailymail.co.uk
 
Greenpeace said:
Meanwhile in Armenia.....

www.dailymail.co.uk

Man puts his BARE HAND straight through fiery molten ore

Is this skill or madness? In this remarkable footage an Armenian foundry worker can be seen putting his hand straight through boiling hot molten metal.
www.dailymail.co.uk
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Eek. Quite a fast wave through the the molten stream, so I suppose he gets away with it as there is not much time for heat transfer. Maybe his hand is wet too, so latent heat of vapourisation may be part of the explanation. It's a bit like the walking on hot coals trick - I gather you indeed can do it without getting burned - low specific heat of the coals and a bed carefully designed to be firm underfoot so you can't sink into them. I'm not about to try either of them....

There is a ranger at Kilauea National Park, elderly now, who stepped into lava as a young ranger when a thin crust failed. Lost both legs below the knees. Double eek that one!
 
56 Fregate said:
Yes, control is very important as is the flow rate. The entire contents of the crucible will need to be poured in in a controlled fashion (not to slow and not too fast) in about 20 seconds. Target accuracy is also important, it all happens very quickly.
Click to expand...
Hi :2cents:
I might think that, while a worm drive might have some benefits, it might be a bit slow for good control unless it was a very fast ratio and thus not self holding. As I remember the foundry pourers had to cut the flow quickly and then reposition and start pouring again with little lost motion or time(temp) lost. That previous brake drum casting video has some ideas to learn(+ some to forget) as I am sure you have done. :rolleyes:

A normal reduction drive like a gear or chain is simple enough and if the load is balanced not hard to control for accurate pouring. Then you can get/make an automatic friction clutch holding device for it, like you can get on a hand winch. It will drive forward and hold but drive back without having to lift a pawl or latch. I could shed some more light on these if you have not noticed them. ;)

The spout will not be at the top will it. There will be some chamber above the metal for heat transfer and adding material and adjusting the mix, then deslagging and other necessary things ??
cheers Jaahn
 
JohnW said:
Eek. Quite a fast wave through the the molten stream, so I suppose he gets away with it as there is not much time for heat transfer. Maybe his hand is wet too, so latent heat of vapourisation may be part of the explanation. It's a bit like the walking on hot coals trick - I gather you indeed can do it without getting burned - low specific heat of the coals and a bed carefully designed to be firm underfoot so you can't sink into them. I'm not about to try either of them....
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Me either. I think it's called the Leidenfrost Effect.
 
At least this Chinese guy's not waving his hand through it, safety first.........

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jaahn said:
Hi :2cents:
I might think that, while a worm drive might have some benefits, it might be a bit slow for good control unless it was a very fast ratio and thus not self holding. As I remember the foundry pourers had to cut the flow quickly and then reposition and start pouring again with little lost motion or time(temp) lost. That previous brake drum casting video has some ideas to learn(+ some to forget) as I am sure you have done. :rolleyes:

A normal reduction drive like a gear or chain is simple enough and if the load is balanced not hard to control for accurate pouring. Then you can get/make an automatic friction clutch holding device for it, like you can get on a hand winch. It will drive forward and hold but drive back without having to lift a pawl or latch. I could shed some more light on these if you have not noticed them. ;)

The spout will not be at the top will it. There will be some chamber above the metal for heat transfer and adding material and adjusting the mix, then deslagging and other necessary things ??
cheers Jaahn
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Hi Jaahn,

There are many things to consider when building a tilting crucible/furnace for a specific purpose i.e emptying directly into a sand mold instead of hand pouring. The dross (nor slag) will be removed by opening the top of the furnace which will be closed again before tilting. Some free board space above the molten metal will be needed to ensure the pouring process can be done in a fast but constant stream from the getgo. I do have a design in my head which involves a counter-weighted pull down handle arrangement so maximum control can be had while pouring. Although I am physically aging and don't have the stamina of a young man I do still have enough physical strength to muscle a properly setup counterbalanced furnace. I'll do some prelim 3D drawing soon to present to the board of interested onlookers. 🤓

But be warned: I fully intend to go ahead with this, just for kicks, like a golfer who spends his spare time trying to perfect his stroke.
 
56 Fregate said:
Hi Jaahn,

There are many things to consider when building a tilting crucible/furnace for a specific purpose i.e emptying directly into a sand mold instead of hand pouring. The dross (nor slag) will be removed by opening the top of the furnace which will be closed again before tilting. Some free board space above the molten metal will be needed to ensure the pouring process can be done in a fast but constant stream from the getgo. I do have a design in my head which involves a counter-weighted pull down handle arrangement so maximum control can be had while pouring. Although I am physically aging and don't have the stamina of a young man I do still have enough physical strength to muscle a properly setup counterbalanced furnace. I'll do some prelim 3D drawing soon to present to the board of interested onlookers. 🤓

But be warned: I fully intend to go ahead with this, just for kicks, like a golfer who spends his spare time trying to perfect his stroke.
Click to expand...
If you pour through an orifice or over a small calibrated v-notch weir, you'll have better control over the flow rate I think. Hydrology of molten ally is a new field but some basic principles transfer from water, albeit with much lower specific gravity.

Project of some sort in mind?? :)
 
Well actually the speed in m/s of the molten metal is controlled by the size of the sprue which is carefully calculated in advance. When pouring the metal into the sprue it is imperative to keep it full from start to finish so air doesn't get sucked into the lava flow. The principle is simple and the execution quite full-on with only one chance to get it right. Simple really.

Project? There's a wise old Hekawi saying: Build it and they will come.
So once I have a bigger furnace the projects will follow.

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I have a plan :unsure:. Check out the device with pneumatic tyres at 2.07 in this video. With a tilting furnace to fill this mobile crucible it would be a sinch to pour a lot of metal very quickly and with a lot of target accuracy. BTW pay no attention to the guy with the hand held crucible that spilled its contents everywhere :cautious:, he mustn't have had his weeties that morning, but it does point out what I said about the need for speed and accuracy, also note they didn't stop pouring even though there were problems.

 
56 Fregate said:
I have a plan :unsure:. Check out the device with pneumatic tyres at 2.07 in this video. With a tilting furnace to fill this mobile crucible it would be a sinch to pour a lot of metal very quickly and with a lot of target accuracy. BTW pay no attention to the guy with the hand held crucible that spilled its contents everywhere :cautious:, he mustn't have had his weeties that morning, but it does point out what I said about the need for speed and accuracy, also note they didn't stop pouring even though there were problems.

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Staggering!! I noted a quick foot movement as it started splashing around.....
 
JohnW said:
... a fast wave through the the molten stream, so I suppose he gets away with it as there is not much time for heat transfer. ...
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Thought of starting a new TikTok challenge?
Just the thing to try at home to collect 'likes'.
 
...in defence of the clumsy chap he probably had about 15 kg of 800 degree liquid alloy at the end of a pole and trying to pour in a small round target in a rotation motion. I once poured 5.6 litres which is 15.1 kg and it maxed me out.
 
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