Challenge to mechanically minded people

[just george]

You have 2 metal shafts that are side by side. They are suspended in the air by bearings, so that either shaft can spin freely. The shafts are parallel.

The teacher has connected an engine to shaft number 1, so that it spins at a constant speed.

You must somehow connect Shaft 1 to Shaft 2, so that as shaft 1 spins at a constant speed, shaft 2 rapidly changes rotation speed.

The speed change must be:

When shaft 1 is at 0 degrees, shaft 2 must spin a full 180 degrees very quickly, and then stay as still as possible, until shaft 1 reaches 180 degrees, at which point in time shaft 2 must spin another full 180 degrees in the same direction as before, and then stay as still as possible again, until shaft 1 reaches 360 degrees/0 degrees, and the process begins again.

That's it.

The solution must be entirely mechanical. No electricity may be used. No motors may be used. Shaft 2 may never spin backwards. No switches may be used.

 

[Cognisant]

XYZ?

Actually can you just copy & paste how your teacher explained it?

When shaft 1 is at 0 degrees, shaft 2 must spin a full 180 degrees very quickly,

Is shaft 1 moving?

and then stay as still as possible, until shaft 1 reaches 180 degrees,

So you want shaft 2 to reach 180 before shaft 1, how much sooner? (by percent please)

at which point in time shaft 2 must spin another full 180 degrees in the same direction as before, and then stay as still as possible again

So two stage process, first stage identical to the first.

The solution must be entirely mechanical. No electricity may be used. No motors may be used. Shaft 2 may never spin backwards. No switches may be used.

Pneumatics?

 

[just george]

I don't have a teacher. It is for a measuring device.

Shaft 1 is the driving shaft, as explained (the engine is connected to shaft 1 to make it move)

Shaft 2 must reach 180 degrees in as short a span as possible. If shaft 2 moved from 0 degrees to 180 degrees in the moment that shaft 1 moved from 0 degrees to 5 degrees, that would be ideal.

 

[Cognisant]

Do you need parts to build this or is it just a thought experiment?

Shaft 2 must reach 180 degrees in as short a span as possible. If shaft 2 moved from 0 degrees to 180 degrees in the moment that shaft 1 moved from 0 degrees to 5 degrees, that would be ideal.

Huh, okay.

 

[just george]

I'm going to build it. If I don't, I'm going to have to build a torquometer and a digital scale and a pendulum in the same unit, which is beyond problematic

 

[Cognisant]

What are you doing?

And hold on I need to draw this.

 

[just george]

What are you doing?

And hold on I need to draw this.

building an experimental apparatus.

 

[just george]

The closest I can get on the existing apparatus without cutting it apart and rewelding it (which sucks, because I hate welding stainless steel without a MIG) is to use either some severe elliptical gears, or to use a reciprocating rack and pinion like that in the animation below (though with a different length and tooth ratio) - and even then, I can't guarantee that it will stay in phase

http://www.mekanizmalar.com/rack_and_pinion_reciprocate.html

 

[Cognisant]

Meh it'll be faster to describe, basically it's like a ballpoint click pen, if you know how a rotary piston works you know how to translate rotation into a linear thrust (hello ladies) you then utilize this motion to store energy in a spring and release the one way catch on the spring, twice per rotation of shaft one, thus giving you a pulsed output (the release of the coiled spring) which via another rotary piston mechanism you can convert back into rotation, the each degree of which you can control with gears and/or a dual cone CVT if you want it to be adjustable.

In essence what I'm describing is an electrical circuit without the electricity, specifically DC to AC conversion, the spring is a capacitor, the CVT a potentiometer, the motor is your power source and the free-running shaft 2 is ground.

Edit: Come to think of it conversion to a linear motion is superfluous, as long as there is a spring involved and a catch/release mechanism it'll work just fine.

 

[Cognisant]

http://www.mekanizmalar.com/rack_and...ciprocate.html

Oh that's clever, you could 3D print that, then if you want to adjust the input or output just add a dual cone CVT somewhere, and you want to be really clever you can make it self adjusting based upon some kind of mechanical feedback loop.

 

[Cognisant]

I'm going to build it. If I don't, I'm going to have to build a torquometer and a digital scale and a pendulum in the same unit, which is beyond problematic

This doesn't have anything to do with anti-gravity or free energy does it?

 

[just george]

Oh that's clever, you could 3D print that, then if you want to adjust the input or output just add a dual cone CVT somewhere, and you want to be really clever you can make it self adjusting based upon some kind of mechanical feedback loop.

Feel like designing it for me

 

[just george]

This doesn't have anything to do with anti-gravity or free energy does it?

No. Those two are easy. Making what I'm making on a shoe string budget...that's harder.

 

[Cognisant]

Tell me what it is I'm designing and I'll design it.

(within reason)

 

[Minuend]

I'd be careful about doing free work for strangers on the webz

 

[just george]

You already know. Something that attaches to a shaft that is being powered by an engine to turn in one direction, that turns a shaft placed next to it in the way described above, with minimum friction.

I could use elliptical gears or elliptical timing cogs, but the ratio of spin isn't extreme enough.

I could use some other form of non circular gear, but Id end up attaching so many extra pieces that friction would go through the roof.

I could use the rack and pinion reciprocating mechanism, but am concerned about phase.

I could use cogs that have a slider escape mechanism, but the rapid twist of shaft 2 isn't extreme enough.

I could use cogs attached to a pistonic locking mechanism that move them in and out of proximity, but the rest of the mechanism is too heavy. The wobble when it gets up to speed (600 rpm) causes too much chatter.

So I need something simple - preferably something that can be 3D printed eventually.

 

[just george]

I'd be careful about doing free work for strangers on the webz

I'll invoice and pay. I don't expect anyone to do anything for free. I'm not building anything dangerous.

 

[The Gopher]

Just George and Coggy working together, to get the job done.

 

[just george]

Actually a worm gear would do it...but friction through the roof. This is really annoying.

 

[Cognisant]

A belt on shaft 1 winds a spring spring on shaft 2 and some latch mechanism lets shaft 2 unwind 180 degrees (asap) every time shaft one rotates 180, the only bit I haven't figured out is how to make this latch mechanism fast enough, still thinking...

I'll invoice and pay. I don't expect anyone to do anything for free.

I take spirits, or souls.

I'm not building anything dangerous.

Well that all depends how heavy these shafts are, at 600rpm shaft 2 is going to be the definition of vibration with all that sudden starting & stopping.

 

[Cognisant]

How big is this, what will it be made of?

 

[Cognisant]

The cam in fig.2 should work.

 

[just george]

How big is this, what will it be made of?

shafts 16mm steel. Shaft 1 is 600mm long. Shaft 2 is only 50mm long. Everything made of steel/stainless steel.

If you can print one in 3D out of plastic that works, I won't send you spirits - I'll send you one of my stills. Does 12 liters of 85% vodka in 4 hours for $30 a run sound appealing? (I have a habit of overengineering things)

 

[just george]

Oh and I meant that the shafts themselves are 16mm, not the distance from centre point to outside maximum

 

[Perfectly Normal Beast]

I'll send you one of my stills. Does 12 liters of 85% vodka in 4 hours for $30 a run sound appealing?

could you ship one to europe?




i can't help with this problem but i have other talents

 

[just george]

I think I figured it out.

2 big cogs that are only partially toothed attached to Shaft 1 side by side. The cogs are aligned on Shaft 1 so that the toothy bits are on opposite ends.

2 small cogs that are 50% toothed mounted on Shaft 2, also so that teeth are on opposite sides.

For purposes of explanation, lets say that that there are 10 teeth on every cog.

Shaft 1 cog 1 has 10 teeth in the region 0 degrees to 10 degrees.
Shaft 1 cog 2 has 10 teeth in the region 180 degrees to 190 degrees.
Shaft 2 cog 1 has 10 teeth in the region 0 degrees to 180 degrees.
Shaft 2 cog 2 has 10 teeth in the region 180 degrees to 360 degrees.

As shaft 1 turns from 0 degrees to 10 degrees, shaft 1 cog 1 engages shaft 2 cog 1 and turns shaft 2 from 0 to 180 degrees as it moves from 0 degrees to 10 degrees. Shaft 1 continues to turn while shaft 2 is stationary.

When Shaft 1 reaches 180 degrees, shaft 1 cog 2 engages shaft 2 cog 2, turning shaft 2 from 180 degrees to 360 degrees as shaft 1 turns from 180 degrees to 190 degrees. Shaft 1 continues to turn until it reaches 360 degrees/0 degrees, and the process starts again.

All I need is some pin or other to keep shaft 2 in the correct position when it isn't moving, so that the system stays in phase with shaft 1.

Damn thing has been bothering me all afternoon.

 

[just george]

could you ship one to europe?




i can't help with this problem but i have other talents

I can send you a diagram to take to a plumber. It shouldn't take him more than half a day to do.

All you need is about 3 feet of large diameter copper pipe, 6 feet of small diameter copper pipe, a male and female nipple to suit the large diameter pipe, a beer keg, a thermometer, a hot water unit element, about 50 kitchen scrubbers made of copper or stainless steel, one foot of 8 inch PVC pipe and 2 end caps for the PVC pipe.

Mine cost me about 20 bucks and a lot of swearing. It was good fun

 

[Perfectly Normal Beast]

I can send you a diagram to take to a plumber. It shouldn't take him more than half a day to do.

All you need is about 3 feet of large diameter copper pipe, 6 feet of small diameter copper pipe, a male and female nipple to suit the large diameter pipe, a beer keg, a thermometer, a hot water unit element, about 50 kitchen scrubbers made of copper or stainless steel, one foot of 8 inch PVC pipe and 2 end caps for the PVC pipe.

Mine cost me about 20 bucks and a lot of swearing. It was good fun

Thanks i might actually think about this. I've got an old-fashioned copper one but haven't got round to trying it yet. All my home-brews seem to keep getting drunk before i've had chance

 

[just george]

Thanks i might actually think about this. I've got an old-fashioned copper one but haven't got round to trying it yet. All my home-brews seem to keep getting drunk before i've had chance

The old fashioned pot stills work, but the internal surface area is so low that you don't really separate everything properly - so whatever comes out of it is concentrated, but still very mixed up ie you get higher order alcohol plus normal alcohol plus smelly stuff (cogeners) plus water in the final product.

So with a pot still, you have to distill the wine to get a messy product, then redistill the messy product to get a less messy product, then redistill again to get something half reasonable. It is very wasteful, and takes a lot of effort.

When you use a reflux still (which is what my design is) it technically does what a pot still does a couple hundred times in one pass, and so even with a really crappy smelly wine to start with, you get a very clean, very concentrated distillate. At it's peak, my still puts out 94% pure vodka that doesn't smell of anything.

So even a total idiot can switch it on (I made mine electric, cos I'm lazy and didn't want any overflow landing on a fire and turning my kitchen into a bomb) and come out with a vodka better than any grey goose in a single pass.

I made mine use 50L of wine in one go (the wine was just sugar with a special yeast added to it), so that I could sit down for half a day watching movies, and only get up every half an hour or so to put a new 2L bottle in, label the full one, and that was that.

With that kind of setup, you can't drink it faster than it comes out. You'd be blind drunk in 10 minutes. So even if you have people leeching off you, it doesn't matter - there's just way, way too much booze.

 

[Cognisant]

All the parts you need are here, except a winding spring.
http://www.smallparts.com.au/products/

 

[just george]

.

 

[Cognisant]

This is about as reasonable as it gets:
http://www.shapeways.com/materials?li=nav

In terms of resolution current hobbyist 3D printers aren't worth the bother, they're fiddly things that almost never work right the first time and even when they do the resolution isn't great, you're far better off sculpting what you want in clay and making a cast from that.

 

[Brontosaurie]

No. Those two are easy.

is this a bad joke or a bad case of delusions of grandeur or that peculiar blend of the two which some people are prone to excuse as inevitable side effect of Ne ingenuity - or, worse yet, consider the very essence of said ingenuity?

is there perhaps some additional possible interpretation overlooked by my mere auxiliary wit?

 

[just george]

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[just george]

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[walfin]

http://en.wikipedia.org/wiki/Leibniz_wheel
Yeah I guess essentially the cam above. Plus a ratchet to stop shaft two from spinning backwards.

 

[just george]

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[walfin]

With the wheel above, since the teeth stick out on both cogs, doesn't that create the opportunity for shaft 2 to spin too far forward and go out of phase?

I was thinking of something just like that, but with indentations on the big wheel so that the teeth on the little wheel would impact on the smooth part of the big wheel and therefore not go forward.

Actually you have me thinking about adding another bit...thanks walfin, you just solved the next problem I was about to face...maybe....ugh this sucks

Hm how about a gear with a spring in it?

There could be a wedge shaped catch to release the spring or something.

 

[just george]

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[just george]

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[Brontosaurie]

Put $2 million in 3rd party escrow to be used for worldwide patenting purposes only, fully contracted as to the terms of the patenting agreement below, and I'll have a guy meet you anywhere in Australia with schematics for a modular over unity device that will provide megawatts of electricity without any kind of fuel or wind or tides, to be lodged that afternoon with his money, with the $2M to be used to lodge patents in all other countries only after you witness a working model.

As per contract, none of your money will be able to be touched by anyone unless the patent is lodged, and you see it - but neither will you be able to see the device then change your mind about the $2M, and do something rotten like go patent it yourself elsewhere.

You'll either be a billionairre, or be dead. One of those. Not my device btw - this was designed in the 70s.

I was kidding about the anti gravity though.

thank you for answering some imagined flattering question evasively and obscurely, deferring whatever actual content could be expected in this entirely irrelevant sub-context created by yourself.

 

[just george]

,

 

[Brontosaurie]

You're right. The proper thing for me to do is to tell you all the bits that I have figured out about an invention this guy has spent his life trying to get off the ground from the little things he said when he thought I wasn't paying attention, so that I can ruin his life to satisfy your curiosity.

Keep your eye on strange news coming out of Greece in the next little while, and we will have this conversation again.

gerson diet

newtonian space

perpetuum mobile

such mastermind of valuable secrets

(or you just have a thing for appearing smart using anecdotes, appeal to authority and general rhetorical hyperbole)

 

[just george]

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