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Show HN: Sketch, connect and simulate gears and chains

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Re: Show HN: Sketch, connect and simulate gears and chains

#41

Post by bmelton »

lifeformed wrote: post #27
ultimoo wrote: post #24

Earlier quoted context omitted.

Great arrangement! It will work. Whether it will be financially feasible to construct such a large system of gears, deploy it in extreme weather, keep it well oiled and maintain it, and then transport the generated power to a usable location are entirely different questions.

Hmm... maybe there are more common sources of strong-but-slow power. The heat expansion of bridges? The weight of vehicles sitting idly at a stoplight? The swaying of skyscrapers? I wonder if you could make a purely mechanical solar panel that way. Get a giant sheet of metal, put it out in the sun, and attach this gear arrangement to it, braced by opposite sides of the expansion. Hmm... I kinda want to make this now.

What you're describing is a move up the Kardashev scale[1]. The Kardashev scale measures how tech-savvy a society is by how they collect and use energy. A Type I society on the scale is able to harness and store all the energy generated on the planet, which we're moving towards now. Regenerative braking and such are definitely progressions in that area, but presumably bigger gains could be had by harnessing the power of tectonic plate movement, volcanic activity, wind, solar, etc.

[1] - http://en.wikipedia.org/wiki/Kardashev_scale

Re: Show HN: Sketch, connect and simulate gears and chains

#43

Post by gknoy »

Sunlis wrote: post #12

Great for touchscreen, but tricky with a mouse. I would like to see an option for drawing gears where mouse down sets the center of a new gear and dragging away determines the radius.

Absolutely what I was about to post. For a mouse user, mimicing the circle construction mechanics (with preview!) used in the geometry construction puzzle app that was linked a few weeks back [1] would be the bee's knees.

1: http://www.sciencevsmagic.net/geo/

Re: Show HN: Sketch, connect and simulate gears and chains

#45

Post by tantalor »

basicallydan wrote: post #13

This is really cool! The ability to save a configuration and share it would be pretty cool, but as well as that, other objects such as sticks which are attached to gears would be a lot of fun. But then I suppose you have to involve gravity :)

Rods and cams would be the next logical step.

Re: Show HN: Sketch, connect and simulate gears and chains

#46

Post by gcb0 »

lifeformed wrote: post #22

I've always wondered - Consider the following gear arrangement: http://snag.gy/Tvsgi.jpg The tiniest push on the gear on the left causes the gear on the right to fly at thousands of RPM. Of course, there would be a ton of friction in the system to overcome. However, what if the left gear was a pinion connected to a rack that was pushed by an extremely powerful, yet slow-moving source, such as a glacier or tectonic pl…

no because speed is nothing without torque.

The right wheel would spin fast, but anything put there to leverage that momentum into energy, be it simple magnetic generator, would be enough to halt the whole system by equalizing the opposing forces, since whatever minimal force it has, will go trhu the same powers that create the initial speed.

Re: Show HN: Sketch, connect and simulate gears and chains

#47

Post by gcb0 »

canthonytucci wrote: post #8

This is cool but I'm learning quite quickly that I'm no good at drawing circles with my mouse, perhaps a bit more forgivness when using the gear drawing tool might make life a bit easier? Overall I'm impressed.

Will probably send a pull request just to be able to draw gears by the diameter or radius instead of the perimeter.

can't even draw a square with the clitmouse...

Re: Show HN: Sketch, connect and simulate gears and chains

#48

Post by jameshart »

lifeformed wrote: post #22

I've always wondered - Consider the following gear arrangement: http://snag.gy/Tvsgi.jpg The tiniest push on the gear on the left causes the gear on the right to fly at thousands of RPM. Of course, there would be a ton of friction in the system to overcome. However, what if the left gear was a pinion connected to a rack that was pushed by an extremely powerful, yet slow-moving source, such as a glacier or tectonic pl…

So the total gear ratio of that gearchain comes out to something like 1119:1, though that's lower than you intended I suspect because you geared it down with a 9:57-or-so ratio on the end. The penultimate axle is geared at 7089:1 with respect to the first axle.

Now while that implies a rotation of one degree of the first axle is accompanied by a rotation of the penultimate axle through 20 or so revolutions, in practice that's not going to happen, because of that ton of friction you pointed out. The friction force acting to stop the last axle turning gets fed back as resistance to your pushing the first wheel, and it gets multiplied back up through the gearchain by the same factor - so the resistance to your turning the first wheel is 7000-times the resistance of turning the last wheel - plus 2000 times the resistance of turning the wheel before it, plus 918 times the resistance of the wheel before that... in total, assuming all friction forces are equal, you're fighting against a force 12000 times the force you need to turn just one gear - just to beat the friction. Okay, so you posit some frictionless maglev bearings in a vacuum, perhaps. But you still want to get these wheels into motion, so then the same multiplier gets applied to the force you need to accelerate the mass of each gear into (rotational) motion in the first place. Getting all those gears spinning requires 12000-times the acceleration to get one of them turning, so 12000 times the force.

And forget about putting a useful load on the end axle - let's put this thing in a car, say, and use it to drive the rear axle. We'll lift up the rear axle and get the engine up to 5000 RPM. Your engine is going to get that axle spinning 7,000 times for every engine RPM - 35 MILLION revs per minute! But when you drop your 1-ton car to get some traction, the engine's going to act like the car weighed 7000 tons...

You could also think of it in terms of energy. If that last gear spins at thousands of RPM, its got a huge amount of kinetic energy from somewhere. It must have come from your 'tiniest push'. Your tiny push has to transfer all that energy - so it can't be that tiny.

tl;dr: no.

Re: Show HN: Sketch, connect and simulate gears and chains

#49

Post by mapt »

lifeformed wrote: post #22

I've always wondered - Consider the following gear arrangement: http://snag.gy/Tvsgi.jpg The tiniest push on the gear on the left causes the gear on the right to fly at thousands of RPM. Of course, there would be a ton of friction in the system to overcome. However, what if the left gear was a pinion connected to a rack that was pushed by an extremely powerful, yet slow-moving source, such as a glacier or tectonic pl…

It would work, but it would probably not be practical in terms of materials - any significantly huge gear ratio driven from the low-motion side will run into problems with the strength of the gears and the degree of friction involved (and the steady-state static friction pressure & friction loss per second of the fastest gears being sufficiently large to make it impossible to move the slowest gears at all)- and even if you have an impossibly strong frictionless gearbox, the strength of the contact patches with the objects themselves becomes the weak point - the pressure will impress a hole right through the tectonic plates, rock, or glacier you're dealing with, rather than spinning the gears.
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