Ann from University of Boulder, Colorado, sent me this fantastic picture:

She says: "Here are our students (undergraduate juniors and seniors, and masters and doctoral students from various engineering fields) holding up their first assignment (kits from your site)."

Thanks Ann!

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First Flip Face prototype for members to download and try.

I'm trying out a few different mechanisms so see which works best and thought you might like to play along at home so if you are a member you can download the parts at the link and make your own. 

This is a successful mechanism. Turn the handle on the back of the box a full turn and the face turns 180°. The mechanism keeps the face in position when it is supposed to be stationary. The only downside I see is that turning the handle a full turn then stopping isn't the obvious thing to do. Ah well, you try it and see what you think.

Print out the parts onto three sheets of thin card (230 microns / 230 gsm) Score all the dotted lines, cut out the holes the carefully cut out the pieces. Dotted lines are valley folds, dashed lines are hill folds, solid lines show where to cut. Fold up and glue together the side pieces making right angled triangle sections top and bottom.

Glue together the drive stiffeners.

Glue the drive stiffeners to the drive wheel on the grey area.

Fold up and glue together the two axles.

Tightly roll up the two drive pins and glue them shut.

Thread the drive wheel sides onto the drive wheel axle lining them up with the two grey lines

Glue the sides of the drive wheel into place so that they are curved.

Expand the cross holes at the ends of the drive wheel with a cocktail stick then thread the drive pins into place.

Fold over and glue together the geneva wheel so that it is double thickness. When the glue is dry, cut out the piece then fit it to the second axle lining it up with the grey line.  

Assemble the handle as shown above.

Glue the two halves of the box together at one end only. Thread the geneva wheel and drive wheel into the correct hole using the picture above as guidance. Glue the washer into place. 

Glue the box closed then glue the washers into place on the back. Glue the handle to the axle then glue the face to the tabs on the drive wheel.

Done! Turn the handle a full turn and the geneva drive advances two quarter turns flipping the face over. Rack and pinion next.

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The continuing adventures of the Flip Face Mechanism.

Here's another possible solution I could try. It is sort of half way between a rack and a gear. It has the advantage of going back to what I was originally aiming at, press down one hand for happy, the other for sad.

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Further adventures with the Flip Face Mechanism.

I've started off by adapting the bi-directional ratchet mechanism so that it turns a full 180° degrees for each cycle. I've done this by reducing the number of teeth on the wheel to four.

Here's the result. It works, sort of.  I could connect a pair of arms to the cross bar, (Under my finger in the picture.) which would then rock back and forth to rotate the face.

The downside is that it really is at the edge of what the mechanism will do, it works, but not easily, not smoothly. 

Two more mechanisms to try. A double ended geneva drive mechanism modified from this mechanism. I have the parts cut out for this, ready to try. I think it will be a good solid mechanism. I plan to put a handle on the back of the box and the face connected to the axle running though the cross piece on the front side of the box, one turn of the handle would make the face on the front turn 180°.

Alternative three, a rack and pinion drive. Also promising.  It could work quite nicely. The face would be attached to the gear with the rack running through the body as a set of arms with hands on each end. It would then just be a case of pushing the arms one way for happy face, the other way for sad face. Watch this space.

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Progress on the Flip Face project.

Okay, so it sort of works. You press down on one arm and the place where the head will be mounted rotates 180° one way, press down the other and it does the same the other way. 

The trouble is, as soon as I let go of the hand the head bounces back perhaps 20°. You might think it would just look wistful but no, it looks crooked. Pah.

Also, the friction on the paper belts is a little high so it jams up very easily.

I think I'll mark this down as a dead end and try replacing the mechanism. I have a few possible ideas to try. Either a very short rack and pinion, some sort of long action ratchet or perhaps as Pookafletch suggested by email, some sort of adapted pop up mechanism. 

A happy mix of frustration and fun.

Expect to see a happy face in the thumbnail next time. :-)

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I'm working on the flip face mechanism again. In this model you press down on one hand and the face turns 180°, press the other hand and it turns back.

It turns out to be surprisingly difficult to make a mechanism that turns a piece through 180°. Here's what I'm working on with the moment, let me know if I've missed an obvious easier solution. 

The face is fixed to the semi-circular shape at the top of the sketch below. This part can turn through 90° left and right from its currently position. It's joined to the arms by a long thin paper strip threaded over a couple of rollers. the rollers direct the paper, ensuring that it is being pulled straight down.

(Apologies for the rather rubbishy sketch! I'll try harder next time :-)

Semi circles are hard in paper, I've gone for a simpler semi-octagon which is a close corollary and works just as well.

Here's the rotating part fitted into place with the paper tape threaded through the support piece and under the first (not actually rolling) roller. 

I'm worried that the rotary piece won't stay in position when pressure is taken from the hand. We'll find out soon!

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I'm usually one to ignore any passing bandwagon preferring, instead, to walk, I've not done anything about FaceBook. Up until now.

Facebook evangelist ffdoc has convinced me that I should take the plunge. To that end, I've started posting on my facebook page (wall?) and have provided a shiny new link at the top right of the website. Take a look around.

My other various social media links are here:

Facebook
Twitter
Youtube

I noticed yesterday that I has missed when my YouTube channel passed 200000 views. Cool!

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I was sent this link by Exscaly. It has an amazing selection of weird and wonderful mechanisms. A rich source of inspiration for your, and my, paper engineering! Thanks Exscaly

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	Amazing Paper Pets Six animated animals to cut out and make. Amazing Paper Pets is a collection of fun moving paper models to press out and make inlcuding Mexican Peck, Bob the Dog and Cat Walk.	Amazon.co.uk Amazon.com
	Gizmos Everything you need to make amazing paper machines! Automata are animated toys that use several basic mechanisms to come alive-and they're made completely out of paper! Using the ingenious punch-out designs included in Gizmos you can assemble six fantastic paper projects.	Amazon.com only.
	Paper Engineering & Pop–ups For Dummies  ...covers a wide range of projects, from greeting cards to freestanding models. Easy–to–follow, step–by–step instructions and dozens of accompanying diagrams help readers not only to complete the diverse projects in the book, but also master the skills necessary to apply their own creativity and create new projects, beyond the book′s pages.	Amazon.co.uk   Amazon.com
	Paper Automata A collection of working paper models to cut out and make. As the mechanisms are operated, the hopping sheep hop energetically and the pecking hen pecks into its feeder. The motley man bows and acknowledges the applause he has earned and the flying fish flaps and undulates its wings. Each of the mechanisms uses a different principle to generate motion.	Amazon.co.uk Amazon.com
	Paper Locksmith A collection of three cut-out models of locks. They include three of the main varieties of lock: combination, mortice and "Yale". The models are colour-coded and are accompanied by a minibook describing the historical development of lock design and possibilities for the future.	Amazon.co.uk  Amazon.com
	Push Paper (Contributor) Innovative, interesting, exciting: the work gathered in PUSH Paper, part of a stunningly designed new gallery series, is some of the best paper art being created today. Thirty contemporary paper artists, from world-renowned names to talented up-and-comers, all put their own spin on cutting, sculpture, installations, pop ups, paper toys and more. A vibrant question-and-answer section with the book's distinguished juror, Jaime Zollars and a biography of each showcased artist complete this visual feast of paper craft.	Amazon.co.uk Amazon.com

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Rotary motion is motion in a circle. As a mechanism rotates it turns about a fixed point. The speed of rotation is measured in revolutions per minute or rpm. This the number of complete rotations made in one minute.

It is the starting point for many mechanisms. Measurement: Rotary motion is measured in either angular velocity, the number of degrees turned in a given time, or in revolutions per minute (rpm). The direction of turn, either clockwise or anti-clockwise is also part of the measurement of rotary motion. The strength of rotary motion is known as the torque, the turning force. Torque is measured in Newton Metres defined as the force of one newton acting at a perpendicular distance of one metre from the axis of rotation.

Examples of mechanisms using rotary motion are wheels, helicopter blades, gears, volume knobs, steering wheel, washing machine drum and the London Eye

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