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        riddles >> medium >> New screw design
        
(Message started by: BNC on Jan 22^nd, 2003, 7:08am)

Title: New screw design
Post by BNC on Jan 22^nd, 2003, 7:08am

The king of Riddlestan called his chief engineer, williwutang.

“willi,” said the king, “you probably aware of the imp problems we have”

Yes. Williwutang knows all about it. In the recent month, herds of evil imps raid the screws in Riddlestan. Using flat metal objects the find, they unscrew any screw they find. The local civilization had practically grinded to a halt.

“We count on you,” continues the king “to find the answer!”
“Hmm,” said williwutang, “maybe we can change the screws from flat head to Philips (cross) heads?”
“No,” said the king. “We tried that, and the imps were able to find smaller object to use as improvised screwdrivers.”
“How about allen heads?”
“No, tried that as well. They were able to find small enough object for that too.”
“So,” goes williwutang, “maybe we’ll use hex flanges…”
“Hush!” screamed the king. “You know that’s a taboo in Riddlestan! I demand you find a new design of screw heads. The new screws must be such that the imps, using flat metal object of any size won’t be able to open. Our esteemed technicians, working with the proper tools must be able to close and open the screws with no problem”
“And,” added the king with a malicious grin, “you have until tomorrow. If you don’t come up with a solution, you shall be beheaded in the city square”

Can you help Willi escape the death sentence?

Title: Re: New screw design
Post by prince on Jan 22^nd, 2003, 3:25pm

I'm not quite sure what the imps are capable of, so I thought we'd have to design a screw with only round orifices, such that no flat piece of metal can affect it. Then, we need a tool that can turn the screw. Here's what I got (though I'm not sure how to describe it):

The screw head is flat, except for 2 small cylindrical indentations (oriented such that they appear round when viewed from above) positioned at, say 12 and 6 o'clock. The screwdriver simply complements the screw. There can be any number of indentations in the screw, but 2 seems simplest.

Theoretically, the imps can get 2 long flat pieces of metal, insert them into the indentations, and apply force such that the screw turns, but it'd be hard (impossible for someone with human-size hands). However, since they're imps, perhaps they can do it. If they are capable of this sort of thing, I'm not sure how we can make a tool that they cannot simulate.

Does this work, or is Willi beheaded?

Just realized that it doesn't matter that the indentations are cylidrical. they can be any shape, as long as they're not along the central axis of the screw. Without our matching tool, the screw is not easily turned.

Title: Re: New screw design
Post by SWF on Jan 22^nd, 2003, 7:58pm

I am not sure what counts as flat, but a pentagonal bolt head like on a fire hydrant might do. Hexagons are taboo, but maybe pentagons are ok.

Title: Re: New screw design
Post by Speaker on Jan 23^rd, 2003, 12:42am

How about reversing the threads.
This way the evil imps, set in their ways to such a degree that they believe that all screws are removed by turning them counterclockwise, and that these evil imps have their own taboos about tightening screws, would turn and turn the screws only to make them tighter. This would most likely lead to mass neurosis culminating in mass suicide by the evil imps. Thus solving the imp problem in a single stroke and elevating young Wutang to the heights of royal society. Or not.

Title: Re: New screw design
Post by towr on Jan 23^rd, 2003, 6:34am

make the screws give a lethal electric shock unless handled with the proper tools..

Title: Re: New screw design
Post by James Fingas on Jan 23^rd, 2003, 9:08am

I don't remember what this shape is called, but it is the second simplest shape of "constant width". First make an equilateral triangle, then make each side bulge out until it is an arc of a circle with its center at the opposite corner. A flat screwdriver of small enough size to fit into the shape can turn freely in the shape.

Title: Re: New screw design
Post by BNC on Jan 26^th, 2003, 4:10am

I was aiming at the answer posted by James Fingas, but it was most interesting to read the other (smart!) suggestions.