...How could any of you not understand how this applies to Hacker News? This is hacking at its finest!!!
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.
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.
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.
Also, lead. Don't use a drinking glass.
I can't check it for myself now but I assume this would also work with lead-free solder. Not that you should put any kind of solder in your drinking glass.
Also, at school, our chemistry teacher heated a rod of glass and asked a boy (who was grabbing an end of the rod in pliers) to run across the room, creating a thin thread of glass.
I don't think they'd do that in schools today, but maybe I'm wrong.
On top of that, I learned how to make metal spheres with physics,some history and saw a bunch of pretty pictures of old towers. All in all time well spent.
I used to live near this.
Cool stuff, even if I don’t quite see how it's relevant here. :P
Someone please calculate this.
It also depends on the diameter of the shot you wish to produce.
I'm thinking that with more thermal mass in the way of the droplet, there's more chance to offload heat, and the difference in ambient temperatures is small compared to the difference to the melting point of lead (>300 deg C)
It's been turned into an enclosed mall in the Melbourne (Australia) CBD. You can see the glass dome covering the whole shot tower building from all over Melbourne.
Skill, but not a great deal if it, is definitely involved, and of course patience as you make then two by two.
Shot, on the other hand ... well, my family has been reloading shot shells since the '70s or earlier (my father has casks of Hercules smokeless powder from plus or minus WWII that he's still using), and the regular charge of shot for a 12 gauge shell is 1 oz plus or minus a little. So let's go for the reasonable worst case, dove, which are as about as small a game bird as is practical, and they require a lot more shooting at than the bigger birds because you generally conceal yourself in a location between sources of food and water, so you've leading them in a way which is particularly difficult.
A single 1 oz load would be 337 pellets of #8 shot. It's usual to go through more than one box of 25 per season ... so, oh boy, would that require "highly patient and dextrous craftsmen", and this activity of both sport and procuring tasty animals would be way beyond the reach of the working class.
(Math is fun.)
I may be wrong though. I wasn't able to find any references about it easily.
A Wikipedia article, concerning a technology that is effectively ancient and indisputably outdated, seemingly with no relevance to any recent events in the tech world, or the greater world in 2013 for that matter.
Occasionally it seems as if one could do "Random" Wikipedia click , find something marginally interesting, and post it here. It's strange that this would be the case, but I suppose the points voted on suggest that the community is interested in the subject. Don't get me wrong, I read the article and found it interesting, just to learn a little something new about history, but I then wondered how it could possibly relate to HN, and I went back to re-read before commenting as I was certain I must've been missing something regarding how this article relates to some current event / technology.
Edit 10:42EST, to restate the purpose as it seems people neglect to realize I too found it interesting and are saying "but it's interesting, I personally enjoyed it", please see the below sentence (Copied from above paragraph for clarity). This comment wasn't about personal interest, it's a question of relevance.
Don't get me wrong, I read the article and found it interesting, just to learn a little something new about history, but I then wondered how it could possibly relate to HN, and I went back to re-read before commenting as I was certain I must've been missing something regarding how this article relates to some current event / technology.
Ninja Edit: Note! The following will direct you to a random wikipedia page, may be NSFW. Follow at your own risk.
On-Topic: Anything that good hackers would find interesting.
anything that gratifies one's intellectual curiosity.
Please don't submit comments complaining that a submission
is inappropriate for the site.
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.
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.
Parent said "very effective", I am not sure what it means if not "efficient".
> Though whether it's inefficient in any other sense is, I think, open to question
Indeed, that's exactly what I meant.
1) Why, exactly, should this not be on HN?
2) What makes a submission suitable to be on HN?
You've said that you found it interesting. You maybe learned something? Your curiosity isn't piqued - do we still use this process, does anyone anywhere in the world use this process, could it be used for anything, what happens if you use other materials or if the air is hotter or colder, or if we try it on the moon or on Mars or etc etc etc?