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Shot tower

en.wikipedia.org

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Re: Shot tower

#41

Post by hga »

ceejayoz wrote: post #38
bnegreve wrote: post #35

Earlier quoted context omitted.

Side (but on-topic) note: I don't necessarily agree that building a 49 m tower to make tiny shot balls is "a very effective solution".

It is if you're making huge amounts of them and you're in the 19th century.

See here https://news.ycombinator.com/item?id=6374682 where I calculate a "single 1 oz load [for dove] would be 337 pellets of #8 shot"

Now, way back when they were probably more using larger sized shot for larger birds (dove are about as small as is practical, and probably more useful for learning real wing shooting), but that gives you an idea of the scale. If you go up to #6 for pheasant and grouse sized birds, 1 oz is 219 pellets.

And, yeah, this is a very cool hack for cheaply making this stuff, which we do indeed use in mass quantities.

Re: Shot tower

#42

Post by guelo »

I thought it was interesting that the modern "Bliemeister" manufacture method still consists of dropping molten lead drops. The difference apparently being the use of heated liquids and inclined surfaces for greater control. https://en.wikipedia.org/wiki/Bliemeister_method#Manufacture

In contrast metal bearing balls are manufactured using cold metal working techniques. Sheering, pressing, grinding and polishing some wire. https://en.wikipedia.org/wiki/Ball_%28bearing%29#Metal

It seems as if lead should be easier to press into shape than steel so I wonder why the difference in techniques.

Re: Shot tower

#43

Post by zokier »

stiff wrote: post #21
jessevdk wrote: post #2

You can try something similar to this (although more related to the older barrel technique) at home with a soldering iron . Melt some tin at the tip while holding the iron at a sufficiently large enough height over a glass of water. It takes some practice to make nice round balls, but it works!

Loosely related anecdote: in a technical electronics high school my teacher showed us, as a cool trick to impress us, how to actually solder this way - you make a nice little ball from tin with the soldering iron, put it over the first pin of a multi-pin chip and let the ball freely fall through the other pins. It takes a lot of practice, but bits of tin stick to pins forming proper soldering joints and the (somewhat…

I'm very sceptical that such procedure would produce proper solder joints. Proper joint requires that both the lead/pin and the pad are heated. Some metallurgy guru could chime in and explain why that is.

Re: Shot tower

#44

Post by mjb »

guelo wrote: post #42

I thought it was interesting that the modern "Bliemeister" manufacture method still consists of dropping molten lead drops. The difference apparently being the use of heated liquids and inclined surfaces for greater control. https://en.wikipedia.org/wiki/Bliemeister_method#Manufacture In contrast metal bearing balls are manufactured using cold metal working techniques. Sheering, pressing, grinding and polishing some…

> It seems as if lead should be easier to press into shape than steel so I wonder why the difference in techniques.

I only worked briefly in a cold-forging factory, but I remember there being issues with wire stiffness and difficulties with getting economical yield when making very small things. We were working with steel, brass and copper, so lead may be different.

Re: Shot tower

#46

Post by mildtrepidation »

bnegreve wrote: post #35
sspiff wrote: post #26

Earlier quoted context omitted.

While it may not be news, and it may not be immediately useful or directly applicable, I found this a fascinating process, and a good illustration how something very simple can be a very effective solution.

Side (but on-topic) note: I don't necessarily agree that building a 49 m tower to make tiny shot balls is "a very effective solution".

Perhaps you mean efficient rather than effective? It does seem to be quite effective, despite the superficially amusing fact that a very tall tower is being used to form a very small product.

Though whether it's inefficient in any other sense is, I think, open to question: The up front expense and difficulty of the tower is a one-time cost, and I'd think maintenance on it would be fairly minimal. I'd think other methods discussed in these comments would almost certainly incur significantly more overhead, particularly over the life of the facility.

Re: Shot tower

#48

Post by Stratoscope »

zokier wrote: post #43
stiff wrote: post #21

Earlier quoted context omitted.

Loosely related anecdote: in a technical electronics high school my teacher showed us, as a cool trick to impress us, how to actually solder this way - you make a nice little ball from tin with the soldering iron, put it over the first pin of a multi-pin chip and let the ball freely fall through the other pins. It takes a lot of practice, but bits of tin stick to pins forming proper soldering joints and the (somewhat…

I'm very sceptical that such procedure would produce proper solder joints. Proper joint requires that both the lead/pin and the pad are heated. Some metallurgy guru could chime in and explain why that is.

When the metal is hot, solder remains melted, flows onto the metal and bonds to it. In fact, when soldering you should heat only the metal parts first and not the solder directly, and then apply the solder to the metal parts where the soldering iron touches them. You never heat solder directly with the soldering iron and expect it to stick to cold metal.

When the metal is cold, the molten solder freezes up as it touches it, making electrical contact but not really sticking. So sometime later, as a result of thermal expansion or mechanical flexing, the solder joint becomes unstuck. This is called a "cold joint".

It's also essential to use flux when soldering. Most solders used in electronic hand-soldering have a rosin flux core in the middle. The rosin melts first onto the metal you're heating, preventing the heat from forming an oxide layer so the solder can bond to the metal. (I think the flux also helps break down any existing oxide layer, not too sure on that part.)

This teacher's technique would result in unreliable cold joints all up and down the pins.

Search for "cold solder joint" for more information and photos of cold joints.

Re: Shot tower

#49

Post by ChikkaChiChi »

In 1782, William Watts disrupted the shot ball industry by creating an unconvential simple solution that produced a cheaper, better output at a faster rate than the established method.

...How could any of you not understand how this applies to Hacker News? This is hacking at its finest!!!

Re: Shot tower

#50

Post by digitalsushi »

lysium wrote: post #9
Pirate-of-SV wrote: post #6

How many feet taller does a tower in northern Alaska need to be compared to one in south Florida? (at 0 feet above average sea level) Someone please calculate this. Thank you.

...to achieve what?

For the balls to form - the Earth isn't a perfect sphere and gravity in alaska is ever-so-slightly greater than further south. (Which means the tower needs to be taller, so the ball is in the air longer)
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