3D Printed Geneva Drive

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Intro: 3D Printed Geneva Drive

This project was originally posted on notes.robives.com

The Geneva Drive is an elegant mechanism used to convert rotary motion into intermittent motion. There is a YouTube video above as well as on my Instagram feed.

I’ve designed the parts for this project in Autodesk Fusion 360. If you have access to a 3D you can follow these construction instructions to make your own 3D printed Geneva Drive.
Download the STL files from the geneva.zip link above. They should be suitable for most 3D printers. I printed the parts out in a variety of colours of PLA from rigid.ink using an Ultimaker 2.

Step 1:

Here are the five parts ready for assembly.You will also need some cyano glue a small screw and a washer.

Step 2:

A dot of cyano glue holds the handle and crank together.

Thread the crank through the hole in the base.

Fit the drive wheel to the crank. A dot of cyano holds the drive wheel onto place. Make sure that it turns freely.

Step 3:

Fit the Geneva wheel over the pin on the base so that it lines up with the drive wheel as shown.

A small screw and washer holds the Geneva wheel into place. Don’t over tighten it as the wheel needs to be able to turn freely.

That’s it! Turn the handle on your completed Geneva Drive to make it work.

Step 4:

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18 Discussions

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duncan_a

2 years ago

Nice Instructables, but I'm not really grasping the practical applications.

I can see that a ten-lobe secondary gear would allow for the digits 0-9 to appear in a window, but that's about it.

What am I missing?

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S.Leungduncan_a

Reply 2 years ago

In watches this mechanism appeared in modified form as "Geneva stop work," which was attached to the mainspring barrel. From Hooke's law we expect the force exerted by a spring to be linear with it's deformation, but in reality this is not the case for nearly unwound or tightly wound springs. The stopwork prevents the spring from either fully being wound or fully unwinding, thus (hopefully) ensuring the spring operates only in this linear region. In modern (the past 80 years or so) times improved spring alloys and escapement design have apparently alleviated the need for this mechanism as it is almost never seen today. Also automatic winding watches cannot use this system as their springs must be able to slip in their barrels. This picture shows the mechanism quite clearly:

https://chronometerbookdotcom.files.wordpress.com/...

Also from the website of a fellow making his own watch from scratch

http://watchmaking.weebly.com/geneva-stop-work.htm...

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rnshagamduncan_a

Reply 2 years ago

In this digital age, people may not appreciate the importance of a Geneva mechanism, but historically, they were the basis for early clocks and watches (hence the name) and more recently, movie cameras and projectors (yeah, I know--all obsolete today). Also, filter wheel change mechanisms, and anything where intermittent rotary motion is required. Check out https://en.wikipedia.org/wiki/Geneva_drive for more info.

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duncan_arnshagam

Reply 2 years ago

Thank you to all those who expanded my thinking on this.
Although I grew up in the non digital age, I made the switch to electronics back when we were still using valve (tubes) and mechanics got left behind a bit for the next 50+ years.
This has reawakened what had been lying dormant for a very long time...

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JoeG17rnshagam

Reply 2 years ago

It was also called the Maltese cross mechanism.

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san_tduncan_a

Reply 2 years ago

At first look I see an potential application for home pets portion feeding :)

Arduino+small motor+printed parts...

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bruce.desertratduncan_a

Reply 2 years ago

Watch some "How it's Made" or "Food Factory" on TV, this is a very common mechanism used in production lines, like kerr mentioned above in filling stations, or stopping a part long enough for a driver to put in a screw, knock out a cut part, etc.

Watch those anyway, because they're fascinating and teach you a lot about the analog world we live in :-)

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BillM80duncan_a

Reply 2 years ago

There were most commonly used by progressive assembly machines using a rotary table. It allowed the table to be indexed to each position while being driven by a continuously turning motor. They're obsolete now, being replaced with servo systems and computer controls.

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deluges

2 years ago

I like gears. These are nice gears. I like them.

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brids78deluges

Reply 2 years ago

Me too, nice gears, GRUNT!

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heath.glover.3

2 years ago

Model railway turntables use this system for track indexing. Very cool write up. Thanks!

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Bombichm

2 years ago

I had never heard of this type of gear. I consider this to be one more tool in my "toolbox," to attack problems with! Thank you.

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JoeG17Bombichm

Reply 2 years ago

This was the heart of 35mm cinema projectors back in the goo ol' days. I dunno whether they are still in use today.

It was used to give an intermittent motion to the film thru' the continuous motion of the motor.

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Gaztec

2 years ago

Standard use in clocks and watches

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nehmo

2 years ago

The concave curve on the main gear can just be an angle with the apex pointed inward. IOW, the curve can simply be 2 straight lines, and the gear can be made with just hand tools. There's no need to buy a 3D printer first.

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Kerr1

2 years ago

very useful when ever a delay in timing is required. In a plant where they are filling bags with candy, a slight delay for filling before the bag continues on for sealing, etc.

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gm280

2 years ago

I like it. Thanks for posting it.