From: Kathleen Marvin, Mon Feb 15 09:50:02 1988
To: tech
Subject: Inventing a machine
I need some help with some 6th-grade homework. I've been doing OK all year (except for a few problems with advance math), but finally have something that's got me and my daughter really stumped. She has to make an invention that is a ``complex machine'' made up of the following simple machines:
- pulley
- wheel and axle
- lever
- wedge
- inclined plane
- screw
She has to have the concept by tomorrow for her science class, and then has to draw it three-dimensionally. (No, there's no time to teach her AutoCAD!) Later, she actually has to make it.
Any ideas??
From: John Walker, Mon Feb 15 10:47:04 1988
To: kmarvin, tech
Subject: Re: The heart of a new machine
- pulley
- wheel and axle
- lever
- wedge
- inclined plane
- screw
All of them?? I know of few real machines that use all of these fundamental machines.
But what the heck...mechanical design was never my strong point, but who can resist a challenge?
The following is a machine to preserve domestic tranquility by reminding a programmer when s/he/it
has been at it too long and it's time to wander upstairs and see if one's spouse is still around.
When one starts to program, light a candle. The base of the candle has a string molded into the wax so that when the candle burns down to that point (after about 20 hours, a reasonable programming interval), the string is released.
The string passes over a pulley (1), and the other end is connected to the long end of a lever (3), the short end of which is in front of a small cart placed at the top of an inclined plane (5). When the string is released by the candle, the weight of the long end of the lever causes it to fall, raising the other end of the lever and releasing the cart.
The cart rolls down the inclined plane on its wheel and axle (2). The bottom of the inclined plane is adjacent to the programmer's keyboard, and the small end of a wedge (4) is placed under the keyboard. As the cart rolls down the inclined plane, it acquires kinetic energy which is expended when it reaches the bottom and strikes the wedge. This drives the wedge under the keyboard, flipping it over, and reminding the programmer that programming is only part of life, albeit the best part.
The screw (6)? That's to drive into the ear of science teachers who make up dumb problems like this.
Portions of this design may be subject to patents issued or pending which are the property of the Turbo Digital Research Foundation, a division of the International Communist Conspiracy.
From: Dan Drake, Mon Feb 15 12:05:15 1988
To: kmarvin tech
Subject: The braining of a new machine
- pulley
- wheel and axle
- lever
- wedge
- inclined plane
- screw
The teacher pulls a rope, on the other end of which there's a weight, the rope going over a pulley (1) in between. The axle (2) that the pulley is on rotates (making the pulley also a wheel (2)). The end of the axle is threaded (6) and moves a nut as it rotates. Attached to the nut is a rod that runs parallel to the axle; on the end of the rod is a wedge (4) that's on its side, as it were, so that it pushes things to the right or left as it advances. What it pushes aside is the end of a lever (3); the other end is thereby moved out of the way of a bowling ball, which proceeds to roll down an inclined plane (5); having picked up considerable speed, the ball rolls off the end of the plane; it is prevented from damaging the floor by hitting the head of the teacher, which, having dreamed up such a stupid exercise, is plainly impervious to damage from a mere bowling ball.
Between thinking this up and writing it up, I read John's description of his invention. The similarity of final result is neither plagiarism nor accident; like stellar parallax, it's something that needed to be done. While his machine is more elegant mechanically, mine directly and more forcibly effects what his does only as an afterthought, and my patent application will be based on that.
Editor: John Walker