I really need to keep a scrap book. I mean, I stick things in my notebooks that I find interesting but what I really need is a systematic scrap booking system for all the bits and piece of interesting ephemera that I see, enjoy and promptly forget. The other I saw a picture of a little brass figurine with one of those rotating happy/sad optical illusion faces on the front. He had his hands out in front of him palm up and when you pressed down on the palms his face rotated. And for the life of me I can not remember where I saw it! I've been thinking about how it would work in paper on and off for a couple of days. There are a couple of interesting problems that might make for a fun project. So here's my first draft:

The face (which I drafted in Illustrator) is fixed to an axle centred between the eyes. Press one arm down and the head rotates 180° one way, press the other and it rotates back again.

The two main problems as I see them:

The head need to rotate exactly 180° them stop. Shouldn't be two hard with a suitably placed stop but I do need to make sure that is stays in place and doesn't 'bounce' back.

Secondly, the arms move only a short distance yet the head has to turn a full 180°. If I was using brass and steel I'd probably use a chain and sprocket.

This is where the interesting mechanism comes in. There are a few different things I could try. My first draft has the arms as a single unit pivoting about their middle. Connected to the arms and running over the head axle is a thin paper belt. As the arms move the belt turns the axle, rotating the face. I'm in the process of putting this together so I'll get back to you on how well it works.  

Keep up to date: Receive the latest blog post by email

The dome on the recent Flying Saucer project was a rough representation of half a sphere. I could have used Blender to create the net as I did in the banana but decided to use maths. Sometimes its quicker to walk than take the bus.

The original design was based on a dome with a radius of 50mm. I decided to divide it into seven sections round by three sections high. You could change this number if you wanted by changing the numbers in the equations that follow.

To find the length of each side I've used a bit of basic geometry. For this I divide each section into two to make two right angled triangles. I know the length of the long side (the hypotenuse, r) and the angle  in the corner so I can find out the length of side a, then double it to find out the length of each side of the seven sided shape.

The corner angle is 25.7° (360/14) To calculate the length 'a' multiply the length of the long side 'r' by the sine of the corner angle. Google is your friend here. You can find out the value simply by entering "sin 25.7 degrees" as a search. Make sure you use the word 'degrees' in your search otherwise it will give you the answer in radians as I found out. Eventually.

Multiply the answer by 50 to find out the length 'a'. You can use Google again can help you with your calculation. Simply type 50*0.433 into the search box. (The asterisk sign is used as the multiplication sign in computer programming, and web searches) Double it to find the length of each side. It turns out is is 43.3mm. Okay - one down, what's next.  

This is a side view of the dome. Each of the three horizontal strips is 30° wide. To work out how high each strip is ('d' x 2) we can use the same technique as with the previous example but this time using sine of 15°.  Google says it is 0.259 with a bit of rounding. Double it and multiply by 50 to get a strip with of close enough to 26mm.

Finally, the values of 'b' and 'c' show how much the side tapers. We don't need an actual length, just a ratio compared to the radius. This time the angles we know are adjacent to the length we are looking for so we'll use cosines. b = cos 30° and c = cos 60°. Back to Google 

b= 0.8660 (that's one I always remember!)

c= 0.5 (I remember that too :-)

So the final step...

This is the shape of each segment plotted onto a computer. We calculated the width 2a (43mm)  first then the length 2d which turned out to be 26mm. Starting with the four sided shape on the left, the left hand edge is 43mm, the right hand edge of that shape needs to he tapered down to the length 'e'. Multiply 43mm by 0.8660 (remember?) resulting in a length for 'e' of approx 37mm. 

The final length is 'f' This is 43mm multiplied by 0.5, the value of 'c', which is 21.5mm.

Plot it all out as above to make one segment.

Copy seven segments, rotating each one by 45° and join 'em up!

And there it is.

To make the seven sided hole in the saucer section I used the same technique I'd used on the Christmas Tree here.

Glue it all together.

"You have the Bridge Mr Worf."

Keep up to date: Receive the latest blog post by email

"Rob:

It's the small details that make all the difference. Spingears is absolulely right. Fortunately, his suggestion is simple to implement. It is just a case of flipping the existing handle design left to right.

The result is that the long tab which rolls round the handle, rolls the opposite direction.

Here's the finished result. It doesn't look much different to the handles that I've been using up till now but when the handle is turned clockwise, the usual way, it slips nicely through the fingers. 

Expect to see this minor, but important change in future models. Thanks William!

Keep up to date: Receive the latest blog post by email

Designing in 3D can be a tricky process. I tend to do most of mine, especially character design, by cutting up bits of paper and sticking them together at different angles. Once I'm happy with my design I cut the bits up and stick them in the scanner before transferring them to the computer. Time to step into the 21st century perhaps. With that in mind I've been trying out various pieces of 3D software.

3D software comes in a whole range of different packages some of them costing many hundreds of pounds. I really want to be able to share what I've learned as I go along so in the end I've decided that I will go for one of the free packages. (That's all I can afford anyway :-) The two main ones, as far as I can see, are Google Sketchup and Blender. 

After trying both I'm currently leaning towards Blender. It has a feature called UV unwrapping which lets you unfold your model into a net ready to cut out. The picture above shows the 3D model I've created from the sketch on the left. I still need to work out how to make the hair but it is coming on. 

If you have any other ideas of free/cheap software I should try, let me know.

Keep up to date: Receive the latest blog post by email

Happy New Year to you all! I've had a peaceful and relaxing time with friends and family. It's been great, now I've returned to the cutting board refreshed and reinvigorated.

I've got loads of new plans for new models and new idea for the website. Should be a fun year!

I'm starting off by creating an animated character model that uses the double crank mechanism. I think it'll be a fruitful mechnism that'll be a good base for many different mechanisms. I'm starting off with this octopus. This is the first draft, quite a few changes of scale and layout need making for the next version but as a proof of concept I'm pleased with it! The double crank make for an interesting movement. The legs, connected to the outer pushrod, swish downwards then after a small delay the body rises up. The result is a realistic fluid motion just like the real thing.

Keep up to date: Receive the latest blog post by email

Check out the custom T-shirt design by Sinner complete with downloadable templates. Nice works Sinner! Anyone else got designs to share?

USEFUL LINK: Original T-shirt Article

Keep up to date: Receive the latest blog post by email

I've being re-laying the front page round a bit today, as you've probably noticed. 

I really wanted to make a feature of Workshop Notes as I think it is the most important part of the web site. To give it a hands-on look I've taken a photo of my open notebook and used it as a background. Over the top of that I've pasted the latest two entries from Workshop Notes. It is all automated, I just need to add a blog post and the web site takes care placing the picture and extract of the text in place on top of the notebook. It still needs a bit of tweaking but it is getting late so I think I'll call it an evening. Night all. 

Keep up to date: Receive the latest blog post by email

I use Adobe illustrator for designing my models, it if fast, powerful and flexible. Illustrator is a vector illustration program meaning that it draws using lines and blocks of colour. The plus side of this is that the files produced are small, great for sending over the internet, and the lines remain crisp and sharp even at high magnifications. the downside is that it is hard to add texture to pictures. And textures are what give pictures depth and life. I could work using a bit map program such as PhotoShop but this means that shapes are harder to draw and edit, and the files are larger. So, time to compromise.

With the BeltBot model I have mixed Illustrator for the lines and shapes with PhotoShop for the texture.

I've not tried this before so I may well develop a different process over time but for now here is what I did.

I created an Illustrator file in two layers, On the right is the top layer, the solid outline and the dotted lines for creases. To the left is the bottom layer showing the outline of the the design and the basic flat colours.

I copied the colours from Illustrator and pasted them into Photoshop.

I've then used the magic wand tool to select areas of the picture and copy them into new layers. In the above picture I've created a new layer called rivets containing the top and bottom row of rivets.

I work my way through the main image dividing it into layers. I finish up with layers for rivets, pins, brass, leather, wood and the background

I can then go through the layers adding effects. To make the rivets look 3D I added a bevel effect as well as a drop shadow and outer glow.

To create a wood grain effect I added noise to the wood layer.

The noise is a little fine grained so I coarsened it with the pixelate tool...

...then stretched it out into a grain effect with the motion blur tool. 

The end result has a lot more depth than the starting image.

I then saved out the image as a jpeg and dropped it back into Illustrator on a layer behind the cut lines and crease lines. The result is a file, not as large as a full page jpeg with sharp easily editable lines but with all the texture I was aiming for.

I hope you like it!

Keep up to date: Receive the latest blog post by email

Been adding detail to the Grrrobot model today. I needed a rivet effect across the bottom of the body. Previously I've added a dotted line with fairly large spacing and wide line.

I wanted a bit more depth. A 3D effect. I created a row of light green dots, 8pt diameter then a dark green set at 6pt and a white set at 2pt.

I completed the rivet effect by stacking them one on top of the other.

The final effect works quite nicely and seems to translate to print well.

Keep up to date: Receive the latest blog post by email

Some days are all about background, putting things in place for the next stage of a model. Today has been one of those days. Lots of work with nothing much to show for it. Ah well.

I've had a couple of ideas for projects and a nice chat with my parents. My dad and I were discussing what it was that makes a metal look like a metal. What quality of the surface gives it that metalic look. It came up again later in the day when I was trying to recreate a metallic effect for the side of a model. I'm fairly sure it is all about the reflections, this makes it hard on a model because as the model is rotated the reflections need to change. What would you think about using kitchen foil in a model? Is it something that everyone has available to them?

Keep up to date: Receive the latest blog post by email