
Geneva drive - Arjuna
https://en.wikipedia.org/wiki/Geneva_drive
======
Arjuna
Original poster here. I thought you good people would find the Geneva drive
interesting. It is so simple and elegant; similar in spirit to the elegance of
a beautiful algorithm.

For further reading on the Geneva drive... don't miss the _spherical_ Geneva
drive design, illustrated in figure 9-3:

[http://ebooks.library.cornell.edu/k/kmoddl/pdf/002_010.pdf](http://ebooks.library.cornell.edu/k/kmoddl/pdf/002_010.pdf)

Although not Geneva drive related, if you want to combine your passion of
horology with human spaceflight, you will truly enjoy "John Glenn's Heuer":

[http://www.onthedash.com/docs/Glenn.html](http://www.onthedash.com/docs/Glenn.html)

Also, thank you all for the great, related links!

~~~
noselasd
Reminds me of all the crazy gears they used in mechanical computers
[http://www.youtube.com/watch?v=s1i-dnAH9Y4](http://www.youtube.com/watch?v=s1i-dnAH9Y4)

~~~
ssewell
To be honest, at first I saw this post and thought, "how is a simple post of
the Geneva drive mechanism news?". But after reading some of the followup and
various links, I've definitley changed my opinion. Some amazing mechanical
engineering in here. Thanks for this great video!

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r4pha
Such a nice hack. If you like this, you might be interested in "Five Hundred
and Seven Mechanical Movements", freely available on google books [0], which I
found on HN a couple of months ago.

[0]:
[http://google.com/books?id=vOhIAAAAMAAJ](http://google.com/books?id=vOhIAAAAMAAJ)

~~~
PhasmaFelis
You can also find animations for many of the movements here:
[http://507movements.com/](http://507movements.com/)

~~~
VLM
Also Cornell's KMODDL, I suppose start here:

[http://kmoddl.library.cornell.edu/resources.php](http://kmoddl.library.cornell.edu/resources.php)

~~~
woadwarrior01
Thanks for the link. I've had both 507 Mechanical Movements and 1800
Mechanical Movements for quite some time now. This seems like a great
reference for mechanisms.

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fernly
I met the Geneva drive when I was trained in servicing IBM 514 and 519
reproducing punches[1], in the mid-70s when these machines were on the way
out. A 514 could reproduce a deck of punch cards[2] at 100 cards/minute. A
punched card was fed from the "read hopper" and a blank one from the "punch
hopper" and moved through the machine under steel feed rollers that were given
intermittent rotation by a Geneva gear.

Driven by the Geneva, the feed rollers would move the cards the width of one
of their 12 rows, then stop. On the read side, that row was under a gang of 80
little bronze wire brushes. On the punch side, the row was over a gang of 80
sharp little steel punches. When the cards stopped a pulse of current went
through the brushes. If there was a hole in the card on the read side, current
flowed on to one of 80 little solenoids. The solenoid would yank a bell-crank
that pushed a punch through the blank card.

The punches withdrew, the Geneva swung its next lobe, and the cards advanced
to the next row. Twelve rows per card, 100 c/m. It was quite noisy despite
heavy sound insulation on the insides of the covers, a distinct brrruup,
brrruup, brrruup overlaid with a general mechanical roar.

[1][http://www.columbia.edu/cu/computinghistory/reproducer.html](http://www.columbia.edu/cu/computinghistory/reproducer.html)
[2][http://en.wikipedia.org/wiki/File:Blue-punch-card-front-
hori...](http://en.wikipedia.org/wiki/File:Blue-punch-card-front-horiz.png)

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bri3d
If you love both watch mechanisms and incredible feats of "traditional"
machining, I highly recommend George Daniels' "Watchmaking." Not only is it a
beautiful coffee table book but it takes the reader through modern (Swiss
lever) mechanical watches all the way, from concepts to workshop design to
machining to assembly. Even if you don't end up reading the whole thing the
diagrams are wonderful to flip through over and over again.

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Zikes
While the article states that its name derives from an early use in mechanical
watches, the modern mechanical watch is far more likely to use a deadbeat
escapement for its intermittent motion. [1]

[1]
[http://en.wikipedia.org/wiki/Escapement](http://en.wikipedia.org/wiki/Escapement)

~~~
BuildTheRobots
The 1949 Hamilton video "How a watch works" [1] is probably worth a look for
anyone interested in more information on timekeeping mechanics.

Bless the 50's... from a time where education videos actually tried to
educate.

[1]
[http://www.samsung.com/uk/support/usefulsoftware/KIES/JSP](http://www.samsung.com/uk/support/usefulsoftware/KIES/JSP)

~~~
dhekir
Not sure what's in your link, in any case here's a Youtube version:
[http://www.youtube.com/watch?v=TQd-0YXqmR0](http://www.youtube.com/watch?v=TQd-0YXqmR0)

~~~
BuildTheRobots
Hilarious. Sorry about that, obviously pasted completely the wrong buffer.
Your video is exactly the one I was going for, though potentially this [1] is
a better quality version.

[1]
[http://www.youtube.com/watch?v=508-rmdY4jQ](http://www.youtube.com/watch?v=508-rmdY4jQ)

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kops
Thanks for the post. Watching that animation reminded what pleasure could be
derived by just watching simple mechanism in action e.g. union joint,
differential gear, rotary engine etc.

~~~
toolslive
I can clearly remember the hypnotizing spell casted by the Lego differential
gear on my 8year old brain. It lasted for weeks.... Come to think of it, I
actually became an engineer....

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Nicholas_C
Is there a drive that does the opposite? A drive that converts intermittent
rotary motion to continuous rotation? I never studied this sort of thing in
school, unfortunately.

~~~
Arjuna
_Is there a drive that does the opposite? A drive that converts intermittent
rotary motion to continuous rotation?_

From the perspective of a mechanical watch, there is a component known as the
_mainspring_. It is a spring that stores energy from either manual winding or
automatic winding.

With manual winding, turning the watch's crown to wind the mainspring is an
intermittent, rotary motion. Alternatively, with automatic winding, a rotary
weight that moves intermittently (e.g., when the wearer's arm is moved) is
used to wind the mainspring.

In either winding scenario, manual or automatic, the result is that
intermittent, rotary motion causes energy to be stored in the mainspring,
which is then subsequently available to provide for continuous rotation of the
watch's mechanics.

~~~
markild
Great answer.

I caught myself thinking along the lines of "of course it's not possible, that
would be preposterous!", but as you say, a watch spring mechanism does exactly
this.

The key concept here is "stores energy".

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xbryanx
Stop by the Museum of Science in Boston to see a whole working wall of these
sorts of mechanisms, or just check out the videos here:

[http://pie.exploratorium.edu/scrapbook/mechanisms/](http://pie.exploratorium.edu/scrapbook/mechanisms/)

The Geneva Movement is here:
[http://pie.exploratorium.edu/scrapbook/mechanisms/52.html](http://pie.exploratorium.edu/scrapbook/mechanisms/52.html)

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nationcrafting
Thank you for posting this. You've just thrown me back 20 years in time, when
I was a young film projectionist in a cinema. The projector we had used this
mechanism to flash the images on the celluloid at 24fps instead of one
continuous stream of light.

And, I just realised I'm not so young anymore...

~~~
johnpowell
I was also a projectionist and I had to rebuild intermittent movements a few
times when we couldn't get a new one fast enough. I was the head projectionist
for three years and we only lost one at a eight screen theater. But the
theater across town that was owed by the same chain went through a few a
month. But I also made sure the projector-head actually had oil in them and
the other theater didn't seem to care.

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franzb
If you liked this, you should love this series about vintage (analog) fire
control computers:
[http://www.youtube.com/watch?v=_8aH-M3PzM0](http://www.youtube.com/watch?v=_8aH-M3PzM0)
(part 1; other parts in Youtube suggestions).

~~~
rootbear
I was going to look those up and post them, but you beat me to it. Until I
watched those videos some months back, I had no idea such mechanisms had ever
existed.

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BrownBuffalo
A link to other amazing Greek designs that often get overlooked -
[http://en.wikipedia.org/wiki/Ancient_Greek_technology](http://en.wikipedia.org/wiki/Ancient_Greek_technology)

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yread
Friend of mine has used it in her creation

[http://www.youtube.com/watch?v=cHiIVPdOL7Y&feature=player_de...](http://www.youtube.com/watch?v=cHiIVPdOL7Y&feature=player_detailpage#t=92)

(bottom right)

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joelanders
Another cool piece of mechanics this reminded me of: the Master Lock Speed
Dial
([https://toool.nl/images/e/e5/The_New_Master_Lock_Combination...](https://toool.nl/images/e/e5/The_New_Master_Lock_Combination_Padlock_V2.0.pdf)).
I think there's an animation of the internals somewhere out there, too.

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makmanalp
I have a question about these kinds of drives. Don't these depend on the fact
that no one is moving and wiggling the whole mechanism? It seems to me like if
the red gear with the slots were to move just a bit out of the way, it'd mess
up the entire mechanism.

~~~
Jtsummers
The red gear is held in place via the axle, and isn't free to rotate because
of the crescent shaped portion on the drive wheel. The spoke on the drive
wheel catches the driven wheel before/simultaneous to the crescent rotating
out of the way and freeing the driven wheel to move.

~~~
makmanalp
Oh wow, I see now. The green circular part pretty much locks the crescent and
thus the red gear into place. That's why there is a gap in the circular part
where the gear is supposed to turn. Thanks!

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agumonkey
I'm fascinated, borderline in love with gears, cams and engines, such as
rotary
[http://web.mat.bham.ac.uk/C.J.Sangwin/howroundcom/roundness/...](http://web.mat.bham.ac.uk/C.J.Sangwin/howroundcom/roundness/applications.html)
or others (I found fun ones on youtube but lost the urls).

If anyone knows reference or current research about their mathematical side
I'd be glad to read it.

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hownottowrite
#212
[http://google.com/books?id=vOhIAAAAMAAJ&printsec=frontcover&...](http://google.com/books?id=vOhIAAAAMAAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false)

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drpgq
As a McMaster engineer, that was cool to see the Iron Ring clock on that page.
I knew it existed, but forgot about it until I clicked.

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FrankenPC
On thing I really appreciate about the Geneva Drive is the built in
acceleration ramp up/down of the pin engagement. Beautiful.

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kaolinite
I would love to learn about clockwork - even if only using CAD (although
actually getting to make something would be even better) - however have been
unable to find any resources for learning about it. Does anyone know of any
good guides for introducing horology/clockwork manufacturing to beginners and
explaining how to get started?

~~~
VLM
Its kind of big, like "teach me about computers". You can learn a lot from
practical applications. I find these blueprints and finished clocks extremely
aesthetically pleasing and instructive:

[http://www.lisaboyer.com/Claytonsite/Claytonsite1.htm](http://www.lisaboyer.com/Claytonsite/Claytonsite1.htm)

I have no connection other than owning some of the plans and very slowly in
the process of building one of the simplest clocks, one with a classic Verge
escapement. I wanted specifically to build a retro Verge escapement and I
don't know enough to advise if that's the best choice for a noob, unless
you've also got a bug to build a Verge...

If you're willing to spend a ridiculous amount of money (like $1 per page!)
"My own right time" by Philip Woodward could be a reasonable book to start.
Borrow it at the library or interlibrary loan. One thing I learned from the
book is the spouses of time nuts are apparently at least as tolerant as the
spouses of ham radio and computer nuts (which is saying a heck of a lot).

This is an area where I know enough, to know I only know enough to be
dangerous, so if anyone has better information they should respond.

(Edited to add I would consider clockmaking to be a separate craft from metal
machining or wood butchering or 3d printing and would not advise trying to
learn both at the same time, unless you're very patient. I think learning fine
woodworking and clockmaking at the same time would be highly challenging. Or
machining and clockmaking, etc.)

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rcthompson
Another interesting property is that unlike a regular pair of meshed gears,
this can only transfer power in one direction. Swapping the input and output
shafts won't work.

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dhughes
Check out "u.s navy vintage fire control computers (part 2)" on YouTube for
similar devices.

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ruuki
That's what I call pure genius.

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kimonos
Nice post! Thanks for sharing!

