The turning turtle project is an idea that I've been thinking about for a while. This picture, from the workshop notes blog shows my original plan. I made up a rough prototype at the time but it didn't work as well as I had hoped. The mechanism itself worked but with the speed of turn of the turtle, it was hard to see the leg movement. At the time I thought about gearing the rotation down so that the legs moved up and down at the same speed but the tortoise turned at one quarter revolution per handle turn. It was all getting a bit complicated.
When I made the ninety degree joint I was looking for a character to add to the top of the box and I remembered the Turning Turtle idea. To keep things simple I didn't try moving the legs.  
 

Following up from the anonymous comment in the Turning Turtle project, there are a few ways that the project could be extended using the ninety degree joint as a starting point. Visit the previous blog post and check out the second comment. 

Two possibilities that I'll look into (when I've finished the Acrobat project). First picture, like the original idea, the legs are connected to a cam surface via cam followers. Perhaps if I increase the range of leg movements it will work better. The second possibility, fix the body so that it doesn't rotate. Inside the body, rotate a cam surface so that the legs, head and tail waggle up and down frantically.

Thank you anonymous commenter. These look like interesting ideas!

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Paper Pop is one of Matt Hawkin's creations. You can download him from Matt's website - Custom Paper Toys

Matt's model is my starting point for a swinging leg mechanism I was originally planning on creating my own but why would you when you can mechanise Andy Warhol! This'll be my fifteen minutes of fame :-) Once complete I'll be making the files available as a free-for-all download.

Matt's file was created in Illustrator, my drawing program of choice, so modifying it shouldn't be a problem. I'm planning to make the head into a wobbly bobble head and have the legs swing back and forth in alternate directions when the model is moved.

First step - the head. I'm added a hinge point right up at the top of the hair so that the head is free to swing. 

Inside the top of the head I've added this piece. It gives me a vertical surface and a flat edge that I can attach a hinge too.

I've also cut out the bottom of the head so that the new neck can pass up though the head to the top of the hair.

Next I added a really tall neck to the body, topped off with a paper hinge which will connect to the top of the head.

Finally, I glued the neck to the head top. The head is now free to swing back and forth. 

Andy Warhol bobble head! Next step - the leg swinging mechanism.

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In the back of my mind I have ideas for various models that I just can't work out. I know what I want to do but haven't worked out how. To me, these models are the really interesting ones. They're especially satisfying when I can finally work out a solution. The latest model to move from this mythical collection into the realm of the solved was the XOR goat. I still have plenty of mechanisms I can't work out though.

Randomness: I like the idea of a paper decision maker. Ask a question, pull the handle and either the Yes character pops up of the No character. For it to work though the chances of each character popping up needs to be randomly 50/50. Making something repeatable in a mechanism is easy, making it random; not so much.

Power: There are a few different models that would benefit from a power source. The wave machine shown here would be neat if it could be made to wave at you across the room, without the need to crank any handles. There are a few possible approaches to powering a model, sand or salt pouring into a waterwheel type machine. Elastic band power - the problem being stopping the model from collapsing under the force of the elastic. Or how about a clock type mechanism with a counter weight and an escapement.
Powered models are the ones I feel that I could solve with a bit of effort and some research time.

Gears. So I actually have a few models that already use gears and they work fine. A single gear to another gear is okay, especially if you are gearing down. But three or more, or gearing up, or even just trying to actually transmit a bit of power and it all goes pear shaped. I think, based on a few experiments, that the main problem lies in the axle rather than the gear itself. A square axle going through a round hole is, by necessity, going to have issues with tolerances. This lets the gear wheel move, and not in a good, round and round, way. If the gear wheel is not accurately fixed on its axis then as soon as you try and do anything interesting with it, the teeth jump. Small holes and a wooden skewer would probably solve the problem but I'm a purist, I don't like idea of using wooden skewers in a paper model so gears stay on my list - for the moment.

There are more of these tricky mechanisms; things that I have yet to solve. For example, I really like the idea of making a butterfly that sits on the end of a thin, delicate branch and opens and closes its wings, the mechanism fiendishly hidden within the branch.

I'm thinking of setting up a section on the websites where I can list these problem mechanisms then tick them off when they are solved.

Any ideas/solutions to any of these would be gratefully received. Back to work on the catapult!

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 I saw a set of paper bellows on Harry Hill over the weekend. They were folded differently from the ones I normally make so I drew a quick sketch in my notebook so that I could remember how it worked. 

Once back in 'the office' I succeeded in converting the sketch into a computer based net. The folding is really tricky but the results are worth the effort. A fun little paper object which may well appear in a future project.

I've uploaded the pdf file onto the website, it is available to subscribers if you fancy a go. Print it out onto ordinary printer paper, score all the dotted lines and cut out the outline. There are no instructions with the file - you'll have to work that out yourself!

I glued up my model with a pritt stick rather than my usual PVA glue. Have fun!

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I spent the morning doing tweeks to the website, I actually got quite a bit done. Can you spot the changes? That'll be it for the day though our friend Paul Smith is visiting so we're having a few beers, talking about art, collabortaion and the imminent collapse of civilisation as we know it.

Check out Paul's website, he makes some beautiful sculptures.

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I'm not sure how much I can say about this model. Some people are quite happy for me to discuss up coming projects, others like things to be kept secret. I haven't checked with this person so I'll keep it brief. I just wanted to point out the legs. They are just flat areas of colour but notice how the addition of a fine white line near the edges gives them a plasticy, shiny effect. Sometimes it only takes a hint, your brain does the rest!

As is often the case I'm working on one project whilst thinking about about two or three others - and doing a bit of website work (and ferrying kids and making the dinner but that's another story)

I've got a book project on the go - I'll have to find out how secret it needs to be so maybe more info soon. And of course, the raspberry project - which I'm quite excited about. I've been thinking about that a fair bit today. I reckon that the sound could, with a little tweaking, be made into a cat's purr. Bellows powered purring cat- could be fun! The current design only works with the airflow in one direction so it would only work as the bellows are compressed not as they are expanded but if I but a couple of raspers back to back it might well work on both directions of the bellows. Certainly worth a try.

Going for some card...

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 I've put the sound generating parts of the upcoming - as yet nameless - raspberry model up on the website for you to download and have a go.

It makes quite a satifying raspberry noise as you'll be able to see now that I've fixed the video below.

Subscriber's can download the print it out and have a go. the instructions are pretty basic so let me know if you have any problems. I'd also be interested to hear if you are successful!

Have fun! 

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I've been working on a project for Furuta-san, my friend in Japan, for most of the day but I did get chance to throw together a quick video showing the last two stages of the raspberry sound device as seen yesterday. This is my first attempt at a workshop notes video - so be kind! As you can see, I need to spend a bit of time framing up! It is tricky when it is just you and a tripod. I promise more videos in the future - they can only get better!

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I'm doing a bit of development work. I fancy the idea of making a model that blows a raspberry. (I'm not sure if that is a UK only phrase - stick tongue out and blow making a rude sound.) I've tried a few prototypes and made a bit of progress!

The first attempt was a rectangular section tube, 20mm wide by 6mm deep. The tongue attached to the far end in the middle. It worked okay but was quiet. The second one (2) was a bit thinner and worked better but after blowing through it a few times the end got crushed (3) and it stopped working. It looks like it is important that air blows down both sides of the tongue, that's what makes it work.

 So, to ensure a smooth air flow I remade the tube, but this time, tapered. Again, the tongue is fastened at one end in the middle and is free to flap up and down. This one (4) didn't work at all! Thinking that the problem was that card tongue was too stiff I re-made it, this time with a paper tongue in a card tube. It worked! Problem was the rasp noise was too high pitched. I reckoned that the paper was light weight, and therefore, fast moving. Next step I made a tongue sandwich, most of it made from paper for flexibilty but with card glued top and bottom to the end. (diagram above) The extra weight slowed everything down. It works great. Just what I was after. I was going to make a video but ended up making school resources for my True Love and now its dark.

Tomorrow I'll be trying to connect the whole thing to a set of bellows. That should be worth videoing!

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New section on the website - the design process. In this short tutorial I show the steps used to create the texture in the background of the Snow Man cover sheet. (Gift Cover Sheet coming soon!)

I've had loads of downloads of the TMC cover sheet. Thanks for your interest everyone!

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