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A simple paper gearbox to download and make. The input gear has eight teeth, the output gear has twenty two teeth giving a gear reduction ratio of 4:11 or almost 1:3



The finished model can be used as a simple to make gear in it own right or as the starting point for your own charater based paper automata projects. Members can download the parts for free at the link. Non-members can download the parts for £2.50

 


Print the four parts sheets onto thin card. (230 micron/67lb) The parts are not coloured. You can make the model more colourful by printing out the parts onto coloured card.

Score along the dotted and dashed lines and cut out the holes with the a sharp knife before carefully cutting out the parts.


The big gear is made from double thickness card. Fold the card in half and glue it down. Leave it to dry completely under a heavy book to keep it flat. Once dry, carefully cut out the gear and fit the square section shaft into place.


On the other shaft fit the two small gear centres glued back to back as shown.


Glue the teeth down on the grey areas leaving the two ends un-glued.


Glue the teeth to the gear centre following the steps in the pictures.


Fold up the base and top of the box to make right angled triangles.


Fold in and glue down the various tabs on the box end.


Assemble the three parts of the other box end and repeat the process of gluing the tabs down.


Glue the four box parts together.


Fold round and close the box. Don't glue the sides in yet.


Roll up and glue down the two axle tubes lining up the ends of the tubes with the arrows on the tube sides.


Assemble the handle in three steps.


Thread the axle tubes into place inside the square section tubes on the two gears. Use the two grey lines for positioning.

Fit the two gears into place with the small gear at the smaller end of the box. Fold and glue down the box sides and glue down the various remaining tabs to complete the box.

Finish off the model by gluing the handle to the shaft with the small gear.

Check out this Instagram animation to see the gear box in action. I'll be using use mechanism at the heart of my forthcoming hippo model. What will you use yours for?


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Sat 19th Jul 2014

Further experiments with the hippo head I made the other day. I'd like to have the bird on the hippo's back hop and and down a little making small quick movements. Meanwhile, I'd like the hippo's mouth to open and close slowly.


Ideally, two or three turns of the handle would be needed for full movement of the head, this would require a little but of gearing down.


I've made various different paper gear designs in the past, this is my latest version. The mix of wide and flat gears makes the larger gear easier to construct, it is simply a piece of double thickness card. The triangular teeth on the smaller gear are more stable that four sided teeth which can easily be squished over.

Here's how everything is fitted into the box.

I'll fit a cam to the large wheel to drive the hippo mouth open. A second cam on the small gear shaft can be used to drive the bird.

I'll be publishing the gear-in-a-box shown here as a kit in the next few days.


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Thu 17th Jul 2014

Back to work on my paper bird :-)



As I'm sure you remember, I'm aiming to
make the beak move and the wings flap by running separate pushrod, one up each leg. In the original I had used a strip of paper as a pull strap but in this version I've used a triangular sectioned rod so that it can be both pulled and pushed. This means that I can drive the beak open rather than having to let gravity do the job.

 


The beak mechanism works quite nicely, I think the push rod should be clear of where the wing hinges onto the body so there will be no problem with both mechanisms colliding with each other.


Here's an Instagram animation showing the mechanism in action. Looking good so far!


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Thu 17th Jul 2014

More wonderous mods from Michael42er. He's taken the Ski Rex model, added his own colour scheme to the box then made a half size, fully working, Son of Ski Rex!



Thanks for sharing the video Michael, it looks great!

 


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Tue 15th Jul 2014

I usually use pdf files for distributing the parts of paper projects. I use Adobe illustrator for designing and pdf files are easily edited using that software. Still, it is always worth trying something new. What if I wanted to send out a paper model via twitter, would it work? In twitter, pictures saved as jpegs can be seen in the timeline. I put together a test piece.


Here's how it looks as part of a test tweet from @robives



There's a problem though. The original jpeg is 195mm wide, the tweeted version is half that. Looks like I need to do a bit more research into this.


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Sun 13th Jul 2014

Prototyping while #truelove watches a Nicholas Sparks type film. I sketched up this idea for a Hippo model...


...then set about making a head from paper. The first one turned out more like a cow.


I widened the snout, moved the eyes and shruck the ears. Mk II looks much better!


Toothy pegs!

Oh, and the baddy got shot and the neighbour was the ghost of the dead wife or some such.


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Sat 12th Jul 2014

In the previous post I had worked out how the bird beak mechanism could be driven via a cam follower under the model. Theory is one thing, time to put the idea into practice. Here's my first draft. The cam follower pivoted on a point roughly 30mm below the box top so I put together the triangular hanger seen here then linked everything up.


As is often the case with prototypes, the behind-the-scenes parts turn out to be quite a mess! Little bits snipped off, other bits folded over. Still, just so long as it works!


I'll be changing it round mechanism so that the beak opens when cam falls rather than the other way round. Not bad for a first draft though :-) Once I have sorted that I should be able to fit a drive for the wings up the second leg.


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In the interests of completeness I've finished off the animation of the bird mechanism. All being well you should be able to see how the mechanism is transferred from the cam, via the cam follower and bell crank and on the beak.

I had a weird problem with Edge. If I placed the lower beak under the body so that the edge of the beak was hidden, the entire body and lower beak disappeared in Google Chrome, worked fine in Safari though. Very odd. Anyway, let me know if you can see this animation okay, thanks!


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Tue 8th Jul 2014

As part of my Adobe Creative Cloud subscription I now have the latest version of Adobe Edge. I had experiniment with Edge before and been able to successfully animate some gears but had difficulty as soon as I tried adding anything interesting like cams or linkages. Parts seemed to float around and weren't grounded where they were suppoed to be. I thought I'd try again with the latest version and the picture I made for the bird project seemed like the perfect starting point.

So here it is. I've made a small animation of the cam and cam follower parts. It looks like it works on my machine but the question is does it work on everyone else's browsers? How does this animation look to you? Please leave a comment and let me know - thanks!

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It works on my Macbook Pro OS X 10.9.3 with the Chrome browser and the Safari browser. That said, I should have made the animation run the other way round, anti-clockwise rather than clockwise. In a real world model running clockwise the cam would crash into the cam follower seizing up the mechanism. Also I should have placed the parts lower in the frame. Ah well - live and learn :-)


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Mon 7th Jul 2014

Sometimes, when I'm making models, I make them up by eye with scissors and paper, other times, and this is one of those times, I use the computer to help me work out how things will fit together. Here, the main part I'm working out is the Cam Follower / Bell Crank piece. It's the turquise pie slice above the brown cam.


Looking a little closer at the same picture shows you more clearly what is going on. I've basically combined the cam follower which tracks along the brown cam at the bottom of the picture with a bell crank which will drive the pull strip (red), pulling the second bell crank in the knee. Now that the design is worked out I can give the paper version a try.


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