Cams are really useful in automata. One crinkly surfaced cam can be used to describe a quite intricate set of movements. Add a couple more cams to the same cam shaft and it is possible to make a automata with a quite complex set of movements.

The limitation is that all of the movement has to fit into a single rotation of the cam. For a complex sequence this means that the viewer has either to turn the handle really slowly or the cam needs to be geared down. If you are a regular reader on the blog you will know that I have been experiment quite a bit with gears with some degree of success.

If I wanted to make a story that took ten turns of the handle to perform I could use some of the gear designs I already have but for a 10:1 reduction or greater that would need either a multiple stage gear box or a really large output gear.

Enter the worm gear. In a worm gear mechanism one turn of the handle advances the gear by a single tooth of the output gear so even with quite small gears large speed reductions are possible. I made a worm gear a while ago but this is the first time I have tried it since I switched to using circular axles.

The output gear is eleven teeth. The short section of worm is turned via a crank handle resulting in the cam shaft turning round very slowly, perfect for a more complex automata.

I've fitted a couple of cams to the cam shaft and mounted the whole into a box. It works okay by does need a bit of tweaking with dimensions to try and smooth out the movement. In this version the handle turns roughly 3/4 turn with the gear moving smoothly then the gear stops for the next quarter turn. I'm hoping that increasing the gear size slightly should overcome that issue. It should be a useful little mechanism once it is sorted!


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£2.50
Download Cam Box
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Turn the handle in the Cam Box and the push rod protruding from the top of the box moves up and down. Vary the cam profile to vary the movement of the push rod. Use this model to experiment with how cams work or as the starting point for other character based models.

Members can download this model for free at the link.


Print out the parts onto three sheets of thin card. (230gsm / 67lb is ideal) I used coloured card for a colourful model.

Score along the dotted and dashed lines then cut out the holes before carefully cutting out the pieces.


Fold the cam in half and glue it down to make double thickness card. Once the glue is dry cut out the cam.


Roll up the two tubes. Align the edge of the card with the points of the arrows.


Glue the cam to the cam shaft outer using the grey line for alignment.

Fit the cam shaft inner into the outer lining it up with the two grey lines on the inner tube.


Fold up and glue down the cam follower.


Glue the cam follower end into place.


Glue the short tube down and wrap the cam follower end round it gluing the end down o hold the tube ino position.


Wrap a small coin in an off-cut of card. (1p UKP 1c US 1c Euro are all ideal. 20mm diameter, 4g weight) Glue it to the cam follower as shown


Assemble the handle in three steps.


Make up the base and the top of the box. The triangle tubes are all right angle triangles.


Make up the two sides as shown.


Glue the sides to the top with the grey arrows pointing to the top.


Fit the cam into place and glue on the base.


Fold round and complete the box.


Glue the tab on the push rod to the cam follower.


Thread the push rod up through the hole in the box lid.

Glue the cam follower to the centre front of the box. (The front is the side furthest away from the hole in the box lid.)


Complete the model by gluing the handle to the cam shaft.


Turn the handle and watch the push rod jump up and down in lively fashion!


Next I'll be completing this Dog's Dinner prototype and showing how you can use the Cam Box to make the dog eat enthusiastically! Nom nom nom!


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Thu 26th Feb 2015

If you like automata and enjoy following along with my design process you're gonna love this new website :-)

Over the next twelve months I'll be collaborating with Dawn Hurton from Cumbria Archives to create a series of wood and metal automata. Each of the twenty designs will feature a historical figure from Cumbria's past in animated action. Dawn will be doing the historical research then making and dressing the puppets and I'll be designing and making the mechanisms to bring them to life. It has turning into a fascinating project so we thought we would set up a website as a record of the journey. This new website will be used to share how it all goes, the high, the lows, the failures and the successes, the laugher and the tear. Come along for the ride!


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£2.50
Download Running Dog
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Running Dog. Turn the handle and see the dog run powered via the mesh gears and crank mechanism

Watch the running dog in action in this YouTube video!

The running dog is based on the Mesh Gear / Crank mkii Essential Mechanism. All the parts, including the Mesh Gear Crank are included in the Running Dog file. Members can download the parts file for free at the link, non members can join in the fun for £2.50

Download and print out the parts onto thin card. (230 gsm / 67lb is about right) Score along the dotted lines and cut out the holes before carefully cutting out the parts.

You will need to construct the Mesh Gear / Crank first, instructions are here.


Once you have completed the box it is time to construct the dog.

Start by assembling the neck and body then gluing them together as shown.


Glue the leg supports into the body with the front piece to the front and the back piece to the back. Make sure that the glued section is upright.


Assemble the stand and glue it into the body.


Fold up and glue down the two linkage pieces as shown so that the short section is made from double thickness card.


Glue the linkages to the leg supports so that they just clear the stand piece.


Make up the four legs by folding them over to make double thickness card then cutting them out. Make the paws in the same way and glue them to the tabs on the ends of the legs.


Assemble the head and ears.


Make up the tail from double thickness card and glue it to the back of the body


Glue the legs to the small tabs on the leg support (arrowed)

Line up the leg so that the centre top of the leg is over the hinge in the leg support. (dotted cross)


Repeat the same process with the front legs.

When you pull the linkages the legs should move up and down freely.


Glue the head to the neck.


Glue on the eyes and nose.


Fit the dog to the top of the main drive shaft gluing it into position .

Glue the two linkages to the top of the box to complete the model.


Turn the handle to see Spot run!


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£2.50
Download Mesh Gear Crank
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Mesh Gear /Crank Mkii

Turn the handle and the mesh gear drives the push rod protruding from the top of the box via a crank. Use this model as an exercise in pure mechanism or as the starting point for making animated paper characters. This model is a free download for all members, thanks for signing up! Non members can also download the parts for £2.50

This is an incremental improvement over the previous version which is still available here. This version will take over the role of Essential Mechanism from the previous one.


Print out the parts onto thin card. (230gsm/67lb are ideal) I used coloured card for a colourful model. You can use coloured, white or patterned card as you choose.

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


Make up the two gears by folding over the card to make double thickness then once the glue is dry carefully cut them out.


Make up the two crank pieces.


Roll up and glue down the four tubes. line up the edges of the card with the points of the arrows.


Fit the crank piece with the two short ends into the gear gluing it down to the grey area.


Make up the push rod.

Make up the push rod ends from double thickness card and cut them out.

Thread the push rod ends onto one of the mid length tubes and glue them to the push rod so that the tube is level.


Fit the short tube into the middle of the large gear and glue it down.


Assemble the gear, push rod and crank pieces as shown.


Fit the small gear to the short square axle lining it up with the grey line.


Assemble the box front as shown. The long side sections are right angled triangle tubes.


Assemble the top and bottom.


Glue together the handle in three steps.


Assemble the box back. Glue the top and bottom pieces into position as shown. Note that the triangle sections on the top and bottom need to be furthest away from the box back


Fit the gear assembly into place with the push rod threaded up through the hole in the box top.

Glue the box front into position.


Glue down the box side flaps.

Thread the long tube through the holes in the box back. Glue the small gear into position.


Complete the project by gluing the handle to the long tube.

Once the glue is dry turn the handle to mesh the gears and drive the crank!


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In a perfect example of how the Essential Mechanisms can be used Michael42er has posted this video of a elegant pair of dancers circling on the top of the mesh gear type 2 box.

Fantastic work Michael, thanks very much for posting!


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Sun 22nd Feb 2015

You're designing your own animated paper model, perhaps a model of a unicorn running or a bear eating a pot of honey or even, why not, a snail race.
What would really help in the design process is if a suitable mechanism to drive the model were ready to hand. That's where the essential mechanism projects come in. Use these starting point mechanisms to bring your own paper character's to life.
Over the past few months I have added several Essential Mechanism projects to the site, now I have collected them all together into one place for easy access. Click on the Essential Mechanism link on the right hand side of the website and you'll be taken to a page showing all the mechanisms currently available.
I often revisit designs, especially starting point mechanisms like these, and make small improvements so over time expect to see designs from the essential mechanisms page retire to be replaced by new improved versions. The old designs will still be available in the shop but only the most up to date will appear on this page. Essential Mechanisms are available for all paid members to download for free.


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...and back to the running dog project. I've completed the parts design and their layout on the compputer file. Next step is to add colour then complete the assembly photography. The movement works well :-)



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Wed 18th Feb 2015

Here's another delightful creation from our friend Mr Cool! This time, featuring two of Ginger the paper cat models from here

Nice one!


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Mon 16th Feb 2015

Website subscriber Helena Hansen's family always make a ginger bread project for Christmas. Previously they have made, among other things, a pirate ship and a roller coaster. This past Christmas they chose a dinosaur theme.

Time was short so Helena decided that they could adapt the poseable T-Rex model from this site and remake it from ginger bread with candy decoration.

Here's the result, doesn't it look fantastic! Thanks very much Helena and family or sending in the pictures, the Ginger Rex looks fantastic, delicious and terrifying in equal measure!

 


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