How to Almost Build an Engine With Only Parts From the Hardware Store [video] • Hacker News Board

Re: How to Almost Build an Engine With Only Parts From the Hardware Store [video]

#21

Post by JoshTriplett » Sun, Jul 28, 2013, 8:23 PM UTC

speeder wrote: post #20

WalterBright wrote: post #19

Earlier quoted context omitted.

You don't even need a magnet. I made an electric motor as a kid out of nails, wire and a battery. It worked pretty good. But, being a boy, I wanted it to work better. So I replaced the battery with a lamp cord and plugged it in. It promptly burst into flames. Awesome!

Once I plugged a toy race track to the outlet (in portuguese we call it "Autorama" I dunno the name in english), I knew enough of physics to expect it to burst in flame... But instead the car got REALLY, REALLY, REALLY fast, shoot out of the track and smashed into the wall. Of course, I happily put a second car on it, and changed the track so that the car does not end smashed, and indeed, I could launch cars all over…

Assuming the track was designed so the cars go forward no matter which direction you place them, the cars likely had a small diode-based circuit to always feed the current into the motor with the same polarity. When you fed an AC current into the track, that circuit in the cars would have acted like a rectifier, turning the AC into poor-quality, high-voltage DC.

The sparks would come from feeding way too much voltage in, enough to jump the gaps caused by momentary losses of contact between the track and a fast-moving car.

Re: How to Almost Build an Engine With Only Parts From the Hardware Store [video]

#22

Post by walshemj » Sun, Jul 28, 2013, 8:34 PM UTC

jasonwatkinspdx wrote: post #16

SwellJoe wrote: post #5

It's kind of fascinating, to me, that internal combustion engines won the car war for so long. Electric motors are so much simpler to build, and so much more efficient from an energy usage perspective. I understand why electric lost out (energy storage, range of vehicle), but I think it could have gone a different way had there been just a couple of nudges in the electric direction at the right time. And, what a diff…

Yeah. It's worth noting that for engines in stationary devices like fabrication tools and machinery, electric totally won. So what made the difference with cars wasn't just the engines themselves, but rather the energy storage/distribution network. Now that we have batteries that are good enough at a cheap enough price, electric is gaining fast despite a lot of cultural opposition.

It took hundreds of years to go from belt drive in factories to individual electric motors which probably didn't get installed in large numbers until post WW1

Even in the late 70's the mechanical technician courses in the UK required you to be able to design an old school belt drive.

Re: How to Almost Build an Engine With Only Parts From the Hardware Store [video]

#23

Post by walshemj » Sun, Jul 28, 2013, 8:36 PM UTC

flomo wrote: post #13

SwellJoe wrote: post #5

It's kind of fascinating, to me, that internal combustion engines won the car war for so long. Electric motors are so much simpler to build, and so much more efficient from an energy usage perspective. I understand why electric lost out (energy storage, range of vehicle), but I think it could have gone a different way had there been just a couple of nudges in the electric direction at the right time. And, what a diff…

Small two-stroke engines used in lawn mowers and the like were incredibly simple. Perhaps a dozen parts for the entire engine. Of course, such things are now banned in California.

a basic 2 stoke has only 3 moving parts I recall from the dim and distant days of my BTEC in Mech Engineering

Re: How to Almost Build an Engine With Only Parts From the Hardware Store [video]

#24

Post by ars » Sun, Jul 28, 2013, 9:26 PM UTC

SwellJoe wrote: post #5

It's kind of fascinating, to me, that internal combustion engines won the car war for so long. Electric motors are so much simpler to build, and so much more efficient from an energy usage perspective. I understand why electric lost out (energy storage, range of vehicle), but I think it could have gone a different way had there been just a couple of nudges in the electric direction at the right time. And, what a diff…

> but I think it could have gone a different way had there been just a couple of nudges in the electric direction at the right time

Gasoline cars were popularized before electric power generation was widespread. It would be decades before the power grid could possibly have supported electric cars.

The Model-T started in 1908 (and there were of course cars before that), the War of the Currents was in the late 1880's. The Model-T represents cars becoming popular, but the War of the Currents was just the beginning of the electric grid.

The first Gasoline car was also around the 1880's (must have been an amazing time to be alive with all those inventions).

It was not until the late 1940's that electricity was widespread, i.e. rural areas which are of course important for long distance travel.

So the electric car would not have been practical until then, and by then of course gasoline was completely entrenched.

Re: How to Almost Build an Engine With Only Parts From the Hardware Store [video]

#25

Post by speeder » Sun, Jul 28, 2013, 9:39 PM UTC

JoshTriplett wrote: post #21

speeder wrote: post #20

Earlier quoted context omitted.

Once I plugged a toy race track to the outlet (in portuguese we call it "Autorama" I dunno the name in english), I knew enough of physics to expect it to burst in flame... But instead the car got REALLY, REALLY, REALLY fast, shoot out of the track and smashed into the wall. Of course, I happily put a second car on it, and changed the track so that the car does not end smashed, and indeed, I could launch cars all over…

Assuming the track was designed so the cars go forward no matter which direction you place them, the cars likely had a small diode-based circuit to always feed the current into the motor with the same polarity. When you fed an AC current into the track, that circuit in the cars would have acted like a rectifier, turning the AC into poor-quality, high-voltage DC. The sparks would come from feeding way too much voltage…

Diodes! Great idea, I should have thought of that.

Re: How to Almost Build an Engine With Only Parts From the Hardware Store [video]

#26

Post by electromagnetic » Sun, Jul 28, 2013, 9:48 PM UTC

larrys wrote: post #11

noselasd wrote: post #8

Earlier quoted context omitted.

I just watched it, what in particular seemed so dangerous it would warrant so much precaution ?

Aerosol can. Spark. Gasoline.

FYI it's an aerosol can of ether starter fluid, which its intended purpose is to be sprayed into carbs to get engines to start. There is literally no way to do this other than how the guy in the video is doing it.

Your concern for safety is rather laughable for the size of the engine he's doing this with. Ether if improperly stored is the most dangerous thing as a can of 50% either having crystallized is a good few grams of TNT equivalent, which would make it a small hand grenade. (however an aerosol can with peroxide inhibitors in is extremely low risk if its new)

Talk to anyone who has worked in a mechanics garage and this video is extremely weak tea. Try being near a V12 when you've just filled every spark plug with ether and you're spraying it into the air intake. Now that'll give you an uneasy feeling like you've just made a potential bomb, but the fact of the matter is that the failure points in engines are valves and gaskets long before any metal part fatigues and becomes dangerous.

His piston chamber appears to copper piping, which don't fragment they split, so there's really no risk there. Think bronze cannon over cast iron.

Re: How to Almost Build an Engine With Only Parts From the Hardware Store [video]

#27

Post by vacri » Sun, Jul 28, 2013, 10:08 PM UTC

jasonwatkinspdx wrote: post #16

SwellJoe wrote: post #5

It's kind of fascinating, to me, that internal combustion engines won the car war for so long. Electric motors are so much simpler to build, and so much more efficient from an energy usage perspective. I understand why electric lost out (energy storage, range of vehicle), but I think it could have gone a different way had there been just a couple of nudges in the electric direction at the right time. And, what a diff…

Yeah. It's worth noting that for engines in stationary devices like fabrication tools and machinery, electric totally won. So what made the difference with cars wasn't just the engines themselves, but rather the energy storage/distribution network. Now that we have batteries that are good enough at a cheap enough price, electric is gaining fast despite a lot of cultural opposition.

I'm not sure about totally won - here is a demonstration of a gasoline-powered flashlight, which might create a resurgence of this method for power tools. At 0:30 he expounds on the advantages of the device.

https://www.youtube.com/watch?v=OcdVaslktBE

Re: How to Almost Build an Engine With Only Parts From the Hardware Store [video]

#28

Post by mikeash » Sun, Jul 28, 2013, 10:26 PM UTC

vacri wrote: post #27

jasonwatkinspdx wrote: post #16

Earlier quoted context omitted.

Yeah. It's worth noting that for engines in stationary devices like fabrication tools and machinery, electric totally won. So what made the difference with cars wasn't just the engines themselves, but rather the energy storage/distribution network. Now that we have batteries that are good enough at a cheap enough price, electric is gaining fast despite a lot of cultural opposition.

I'm not sure about totally won - here is a demonstration of a gasoline-powered flashlight, which might create a resurgence of this method for power tools. At 0:30 he expounds on the advantages of the device. https://www.youtube.com/watch?v=OcdVaslktBE

And let's not forget compressed air, which is still a very popular way to run power tools. Electric vastly outnumbers it, of course, but compressed air is still used in a significant portion of tools.

Re: How to Almost Build an Engine With Only Parts From the Hardware Store [video]

#29

Post by mikeash » Sun, Jul 28, 2013, 10:29 PM UTC

DanBC wrote: post #7

SwellJoe wrote: post #5

It's kind of fascinating, to me, that internal combustion engines won the car war for so long. Electric motors are so much simpler to build, and so much more efficient from an energy usage perspective. I understand why electric lost out (energy storage, range of vehicle), but I think it could have gone a different way had there been just a couple of nudges in the electric direction at the right time. And, what a diff…

It's interesting that I can make a toy electric motor by with a battery, a magnet, and some wire. While some people do make tiny internal combustion engines the work involved in incredible. ( http://www.youtube.com/watch?v=mLn7xG8vuPQ ) World's smallest V12 engine: ( http://www.youtube.com/watch?v=m3KdpzL3Hkk ) Making model IC Engine valves: ( http://www.youtube.com/watch?v=Nofj1CGSCM4 )

That's not a fair comparison at all. Building a hobby V12 like that is like building a modern brushless high-efficiency electric motor, not like building the toy you mention.

The combustion engine equivalent to the toy electric motor would be a simple stirling engine or even a Hero engine. These can be very easy to build.

Re: How to Almost Build an Engine With Only Parts From the Hardware Store [video]

#30

Post by bigiain » Sun, Jul 28, 2013, 11:42 PM UTC

mikeash wrote: post #29

DanBC wrote: post #7

Earlier quoted context omitted.

It's interesting that I can make a toy electric motor by with a battery, a magnet, and some wire. While some people do make tiny internal combustion engines the work involved in incredible. ( http://www.youtube.com/watch?v=mLn7xG8vuPQ ) World's smallest V12 engine: ( http://www.youtube.com/watch?v=m3KdpzL3Hkk ) Making model IC Engine valves: ( http://www.youtube.com/watch?v=Nofj1CGSCM4 )

That's not a fair comparison at all. Building a hobby V12 like that is like building a modern brushless high-efficiency electric motor, not like building the toy you mention. The combustion engine equivalent to the toy electric motor would be a simple stirling engine or even a Hero engine. These can be very easy to build.

Building a high-efficiency brushless motor isn't particularly hard - especially if you're happy to consider "reusing/repurposing components from readily available 'junk'", or buying kits like this:

http://www.customcdr.com/cgi-bin/ccp51/cp-app.cgi?usr=51H817...

(I've built both kit versions and "from scratch" motors built with parts ratted from cd rom drive motors with a few bucks worth of rare-earth magnets.)

Building your own controller for it is somewhat more challenging…