I've finalised the layout for the mechanims that will drive the caterpillar model. There are a few small changes that I have made to the original design including mounting the slider inside the box and adding windows to the to side of the box so that the bell cranks are visible.

Just the caterpillar to do!

Double crank mechanism for paper caterpillar. #papercraft #automata #crank #mechanism

A video posted by Rob Ives (@robivescom) on

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It was such a delight to see the Dancing Man model being used on the Belgium TV show de Schuur van Scheire!
I mentioned in my last newsletter that the video was great to see even though I didn't understand the words. Rising to the implied challenge, newsletter subscriber Charles sent me an email with a translation of the video. It goes something like this
In a few words :
Their wives have been complaining about why they do what they do so they decide to find useful things to do with the Dancing Man, each of the scenes then shows one of these ideas:
To replace our king when he is travelling abroard ("and it is cheaper")
As a dance teacher.
For people who want so see more police on the street.
As a goal keeper. Thibaut Courtois

Thanks Charles, that was really helpful!
You can see the video clip here.

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Thu 19th Mar 2015

I'm delighted to have had some of my paper models featured on the Belgium TV Show de Schuur van Scheire.

There are loads of clips from the show on YouTube that you can visit via their page.

Including this amazing clip of a giant Dancing Man paper project they they have made from corrugated card. Check out the videos, they're great!

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Wed 18th Mar 2015

I'm delighted to present two videos of models both based around the Worm Gear mechanism.

Firstly we have a pop up mole from the creative mind of our friend Mr Cool. His used a free mole model from this Japanese site and added it to the worm gear box to make this charming model.

Then we have a video from regular friend of the website Michael42er featuring a mash-up of the Early Bird model and the worm gear. I particually like the way he has cut out the box side to reveal the worm gear in action!

Thanks for sharing both, I really enjoyed seeing them!

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Download Worm Gear / Cam
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See the Membership page for more details.

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Turn the handle on the Worm Gear / Cam box and the gear inside advances one turn for each turn of the handle, a speed reduction of 12:1. Inside the box is a snail cam and cam follower which slowly lift as the gear turns and then suddenly drop at the end of the twelve turn cycle.

Use the Worm Gear / Cam as an interesting exercise in pure mechanism or as the starting point for your own character based paper automata.

Members can download this model for free at the link. Thanks for signing up! Non-members can download the project file for £2.50.

Print out the parts onto three sheets of thin card. 230gsm / 67lb is ideal. I have printed the parts onto coloured card to make a colourful model.

Score along all the dotted and dashes line and cut out the cross-hatched holes before carefully cutting out the model.


Fold over the gear to make double thickness card then card carefully cut it out.

Fold over the cam to make double thickness card as well. Once the glue is dry carefully cut it out.

Roll up the three tubes and glue them down lining up the ends with the points of the arrows.

Thread the gear and the snail cam onto the square shaft lining them up with the grey lines. Make sure the cam is the correct way round.

Assemble the cam follower.

Glue on the tab...

...then the short section of tube.

Roll the tab round and glue it into position between the two triangular tubes.

Take a penny piece (20mm diameter 4gram weight) Wrap an off-cut of card tightly round the coin and glue it down. Glue the coin to the cam follower just behind the tube.

Fit the wider tube into the worm axle Line it up with the grey lines.

Start at one end of the spiral grey line, glue a section of worm to the shaft. Try and keep it as perpendicular to the shaft as possible.

Glue the next one in place overlapping the first by one face width of the hexagon tube.

Work your way down the tube in the same way gluing each piece down with a full face overlap.

Once complete glue the five pieces of worm gear together.

Assemble the handle in three steps.

Fold up and glue the triangle tubes on the box ends.

Fold up and glue the right angle triangles on the box top and base.

Glue the sides to the top as shown.

Thread the gear into position and glue in the base. The gear should turn freely in the box holes. If it does not, remove the shaft and expand the holes very gently with a pencil.

Glue in the two box side stiffeners next to the cam shaft but not so close that they stop it turning.

Fit the worm gear into position.

Close the box front locating the worm shaft into position. Glue the handle to the shaft.

Glue the end of the push rod to the cam follower.

From the back of the box, thread the push rod up through the hole in the box top then glue the cam follower to the back of the box. Once the glue is dry turn the handle and the cam will inch round incredibly slowly.

Perfect for making a tortoise that peeps out of her shell? Or a snail creep along or perhaps a sloth in a tree?

Whatever you create with this useful mechanism be sure to share photographs with the rest of the website visitors by emailing them in!

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Thu 12th Mar 2015


Late stage prototype for a caterpillar project:

The model uses a double crank with a ninety degree offset on the second crank. The caterpillar is then driven via push rods and a pair of bell cranks to make the Inch-Worm movement.

I have a few tweaks to make to the caterpillar. It catches a little as it moves so I need to make some small changes to the design of the individual sections, I'm also planning on making it a bit smaller so that it goes flatter at full stretch.

Cute though dontcha think?


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Mon 9th Mar 2015

Here's the plan. Using the worm drive from the previous post, I'm planning a snail model. Turn the handle and the two cranks in the box will turn really s-l-o-w-l-y moving the snail head back and forth hopefully giving the impression of a slithering snail. The head will be driven by one crank and the tail by a second crank following ninety degrees behind.

Something like this...

Here's my draft version of the double crank.

And here it is fitted into a box and linked up to a couple of bell cranks.

The mechanism also makes a really nice crawling caterpillar. (I think they are called inch worms in the US) So to that end I've also been experimenting with segmented bodies.

The caterpillar will work better without gearing down. I seem to have three or four interesting models on the go here so I'll be concentrating on finishing them off and getting them posted to the site over the next few days. Should be fun!

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I love it! Our friend Mr Cool has mixed one of Walter Ruffler's models with the Essential Mechanisms cam box and come up with this delightful snapping dragon automata. Thanks for sharing!

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After some more experimenting I've put together a working worm gear mechanism with a 12:1 speed reduction. Here's the Instagram video of the model in action.


Worm gear cam in-a-box #papercraft #papertoy #automata #mechanism #gear #essentialmechanisms

A video posted by Rob Ives (@robivescom) on


I tried a variety of different gear profiles before finally settling on the yellow one here.

I put together an almost two turn worm and a geared camshaft.

The two parts fit into a box with a cam follower.

I'll put together a download with this mechanism and probably another with a worm gear driving a crank rather than a cam. I have an idea for a snail model which could be based on this mech, you can see a sketch of it it in my Instagram stream.

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Mon 2nd Mar 2015

More work on the worm gear. I've been trying out a few different variations in design. This is what I've come up with so far:

In the original version, the walls of the worm part were prone to bending over if to much pressure was applied to them. I've greatly reduced this tendency by reducing the height of the walls and by making the worm section one and a half turns instead of one turn. The biggest change though is that the centre core is now a hexagon instead of a square and is now ten millimetres in diameter instead of eight.

I also changed the size of the driven wheel to nineteen teeth though I think I might reduce it back to about twelve teeth in the next version.

In the hand held test the worm and gear work beautifully smoothly. The true test comes next though, when I mount them both in a box.

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