Archives: Evolution of the Screw
My good friend Jeff Mann, the true Yard Ramp Guy, has asked me to revisit some of my original contributions. And so, my From the Archives series. This week: Turn, turn turn: the evolution of the screw.
Screws are a magnificent invention. I've talked about them plenty – think of them simply as ramps wrapped around an axle – so why wouldn't I be interested? They’re simple machines and they literally help batten down the hatches. I figure it’s time to unscrew the lid on their history.
Our old friend Archimedes probably invented the screw. Archimedes' screw is used to pump water uphill, usually for irrigation, through a tube with a metal screw inside: as you turn the screw, the threads scoop up water and push it to the top.
Archimedes' screw
Interestingly enough, we still commonly use this device, and also turn it in the opposite direction. In the Archimedes turbine, water flowing downward turns the screw, which itself is the center of a hydroelectric generator.
Within a few centuries of their invention, screws were appearing all around the Mediterranean in the form of wooden screw presses. We used these to smash olives for olive oil and to smash grapes for wine — both major products of the region. Later on, the screw press would also be a vital component of Gutenberg's printing press.
Me, rummaging for my turnscrew.
Have you noticed a pretty major use that's missing here?
That's right: screws weren't used as fasteners. Instead, there were nails, welding, dowels and pins, etcetera, etcetera. This list of “alternatives” is substantial. In fact, we didn’t use screws as fasteners for nearly two millennia after Archimedes invented them.
What was missing? The screwdriver. (Fun fact: we used to call screwdrivers “turnscrews.”) We didn’t invent the screwdriver until the 1500s. Even then, we rarely tended to use screws as fasteners.
The final piece of the puzzle? The creation of machine tools necessary for manufacturing metal screws. Until that happened, they were just too much trouble to produce in large quantities.
Since we optimized that production angle, we haven't stopped turning them out.
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Archimedes' screw gif by Silberwolf (size changed by: Jahobr), CC BY-SA 2.5, via Wikimedia Commons.
Archives: Space Elevators
My good friend Jeff Mann, the true Yard Ramp Guy, has asked me to revisit some of my original contributions. And so, my From the Archives series. This week: The ups and downs of space elevators.
When it comes to getting into space, rockets are pretty much staircases at best. More like ladders, really.
Space Elevator
That's a bizarre thing to say, I know, but hear me out. Rockets are expensive and dangerous, but they're still the best way we have of getting to space. (There are a couple of other ways, like Orion drives, but given that those things basically ride nuclear explosions...) There's a theoretical method, that works much, much better: the space elevator. (Hence the staircase joke. Well, I thought it was funny, at least. So I'm not a professional comedian, so sue me.)
A space elevator is, essentially, a long cable—anchored at the equator, extending out into orbit. It works sort of like when you spin while holding a rope, and the rope is suspended above the ground by centrifugal force. (Or is it centripetal? I can never remember.) It's not quite the same, of course, since it has to have a counterweight at the end, along with several other requirements.
Once the cable is up, cargo and passenger pods would be able to freely move up and down it, at much, much lower costs than rockets.
Did I mention how expensive rockets are? Really, really expensive. As in: $10,000 to $25,000 per kilogram they need to lift. (For those of you who don't have your measurement conversion tables memorized, one kilogram is equal to a bit more than two pounds.)
A Carbon Tube
So why aren't we using them now? Well, because we don't have a strong enough cable. People keep bringing up carbon nanotubes as an option, but since we don't have those yet, we just can't build it.
The space elevator would be more than possible on other, smaller objects in the Solar System. We could build a space elevator on the moon with ordinary Kevlar.
Space elevators aren't the only ideas for getting to space without rockets. Other ideas are floating out there, ranging from rocket sleds (which does actually involve rockets, but in a much more affordable manner) to skyhooks, which resemble something that a mad scientist, a six year old, and an engineer would design together if asked to create the nuttiest amusement park ride ever, all while hooked to caffeine IV drips.
From the Archives: Kiva Robots
My good friend Jeff Mann, the true Yard Ramp Guy, has asked me to revisit some of my original contributions. And so, my From the Archives series. This week: Kiva robots are a bit like forklifts.
Amazon is the biggest online retailer in existence. On some of their busier days, they've been known to receive more than 400 orders per second. Anyone who has ever worked in a warehouse can tell you that this is an absolutely astounding number. Even with warehouses all over, this would be a huge challenge for human workers. So, in 2012 Amazon purchased an army of robots for three quarters of a billion dollars.
The Kiva robots are like big, square Roomba robot vacuum cleaners, though they function more like forklifts. They're about 16 inches tall and weigh 320 pounds When a customer orders something on Amazon, a robot is dispatched with orders to retrieve the tall, thin square shelf that the item is on.
Kiva Robots: A Standing Army
The Kivas roll through the Amazon warehouses, carefully guided and controlled by a central computer to avoid collisions. They scoot under shelves, stopping when they reach the programmed location and spin in place to lift the shelf. Then they pilot the whole shelf to a station where a human employee grabs the customer's order. The order then travels through an array of other steps to get to the customer.
Amazon has more than 15,000 of these robots in their warehouses right now, processing a majority of the orders. Establishing a testing a system for a warehouse can take quite a while, sometimes months.
Amazon's engineers have to assure that the army of robots on the warehouse floor can move about without running into one another and toppling shelves over left and right, which is no easy task.
They also have to set the system up for prioritizing where to set shelves, in order to minimize retrieval times for the robots.
Surprisingly enough, the Kiva robots haven't resulted in job losses. Instead, the workers move from the picking-and-sorting jobs to train in other positions. In this scenario, when more robots are added, more work is created for the human workers.
Seemingly: everybody wins. Plus, as anyone who has ever worked in a warehouse can easily attest, picking is a job tailor-made for robots.
Archives: The Amazing Spider, Man
My good friend Jeff Mann, the true Yard Ramp Guy, has asked me to revisit some of my original contributions. And so, my From the Archives series. This week: spider silk!
Oh, What a Tangled Web We Weave
Another Busy Day at the Office?
If you're not a fan of spiders, you may want to skip this one. Otherwise, I just might’ve already snared you:
Spider silk is one of the most magnificent substances in nature, and there are a ton of different types of spider silk.
The silk can be used to capture prey. Along with their classic web-shaped design, spiders build webs in orbs, tangles, sheets, lace, and domes. One type of spider even lowers single-strand webs to go fishing.
Spiders tie up their prey in webs; a few species actually have venomous webs they use for this purpose. Other spiders produce extremely lightweight webs for “ballooning”—spiders blown along for dozens or even hundreds of miles by the wind, often in enormous swarms. (Yay, Australia!) Others use silk to lay trails to and from their web, and create alarm lines with it.
On top of that, spiders usually are capable of creating multiple types of silk—up to seven types in a single species.
Humans have studied and adapted countless different uses for spider silk. The spider-silk protein is comparable in tensile strength to high-grade alloy steel at one-sixth the density. We have stronger materials, like Kevlar, but none nearly so lightweight. (The strongest spider silk variety is more than ten times stronger than Kevlar.)
Spider silk is extremely stretchy and ductile, retaining its useful properties across a huge temperature range. The silk even makes for excellent bandages, due to its antiseptic qualities, and contains high amounts of vitamin K, which is useful in clotting blood.
Yes, the stuff that spiders spin is extremely useful. So, why don't we use it industrially? Because spider-farming doesn't work. Spiders eat each other. Instead, we've turned to genetic engineering. We've tried altering silkworms, E. Coli, goats (they produced it in their milk), tobacco plants, and potato plants to produce the protein.
We haven't mastered silk well enough to mass-produce, yet, but it'll happen eventually. (And then we'll get spider-web suspension bridges. Completely not creepy!)