Mushroom Shelving

After finishing building the desk for my new study, I had a large chunk of OSB board left over. I thought I’d design some overly ornate shelves that I could make on the shop bot at FabLab. Since I was using a CNC router I decided to use straight lines when absolutely necessary. I’ve always thought cutting square’s out with a CNC machine was a waste of potential!

I ended up with a design for some shelves that are loosely inspired by the Pleurotus ostreatus mushroom that grows out of tree trunks.

shelf on wall

The main challenge to make these shelves was to cleanly cut the OSB without it splintering. Because the wood chips in this board are so large, they can very easily tear out and look horrible. To avoid the splintering I first cut halfway through the board with a down cutter. The downward spiral on these cutters pushes the chips into the board as it cuts so the top edge doesn’t fray.

first down cut on shopbot

After I’d cut the pockets and half cut the edges with the down cutter I switched to an up cutter. This cut through the final thickness of the board and meant the bottom edges didn’t splinter either. The close-up below shows the edge quality straight off the machine.

edge closeup above 2

Although the cuts came out perfectly for these shelves I made a few mistakes with the design. The diagonal supports don’t lie flush against the back board, and I found cutting OSB to a point is not a good idea. With this in mind I’ve updated my design so the parts fit together more snugly and don’t taper into ragged points!

You can download my design in either Autocad DXF or PDF format. I used 18mm thick OSB to make these shelves, although you can make them out of any board which is 18mm thick if you want. On the drawings the yellow parts need to be cut as 11mm deep pockets, and the green lines are the outlines that must be cut all the way through the board. I recommend using the DXF file if possible since it preserves the curves more accurately than the PDF file does.

Download DXF design : Download PDF design

3D Printed Raspbmc Case

When I was visiting my brother for christmas this year he introduced me to the Raspbmc media center project. When I returned home, I set this up on my own raspberry pi, then started thinking about what sort of case to put it in. I’d been thinking about designing a case based on two layers of laser cut acrylic with a 3D printed chassis in between for a while. Now my chance had arrived!

Raspbmc case Closeup

My first full prototype of the case. Superficially this is the finished item, I need to improve the PCB clips and add a protective cover on the bottom. There’s also an experiment with completely 3D printed light pipes that could be added in if it works!

First full Raspbmc case design

The shape is based on the XMBC logo, redrawn at an aspect ratio that fits the Pi circuit board. The sweeping sides of the case allow clear access to the ports on the Pi, as well as satisfying my taste for organic shapes. Now I’ve seen it printed I may change the lofting so that less support material is needed for the 3D print.

rPi case clips V2.0

As I write this, the next prototype is in the bath at the Manchester Fab Lab dissolving the support material from it. We’ll see how well the 3rd design iteration of clips work. When I was clipping the case above together, it took me ten minutes to fit the PCB and I thought I was going to snap my Pi in half doing it!

Two weeks from now, I should have a case design that I’m happy with!

For more pictures check out the full set on Flickr!

Turing Sunflowers

A couple of months ago I was watching ViHart on youtube and suddenly discovered fibonacci spirals and their endless examples in nature. I was fascinated by the simplicity of the maths but the perfect solutions they form. Since I’ve always taken much of my inspiration from nature, I realised I could cheat for my next project. Instead of  taking inspiration from nature, I was stealing it’s secrets!

Sunflowers are a great example to start with, which is why Alan Turing spent time studying them. When sunflowers are growing they need to evenly space their seeds into a circle. They don’t do this at random, or in a perfectly evolved pattern that’s the same for every sunflower. There is a beautifully simple mathematical pattern describing where each seed will be. When you know all the secrets of this pattern, you realise that it’s not a miracle it exists but an inevitability!

Sun Flower Close - Up Part III

After I’d got the maths of the pattern down, I built a plugin for the open source illustration program Inkscape. So I could easily create and play around with these patterns. It also meant that I could use all the features of Inkscape to change the simple shape on the left into the solid physical outlines on the right.

These are the patterns that turn up all over nature, but I wanted to tweak them a bit to make them look more interesting. The polygons are all pretty much the same size and evenly distributed, that’s the magic of the pattern. I started adjusting how the underlying points were spread out from the centre. This gave me the patterns below:

wooden placemat

earring

acrylic coaster

With just a bit of time at the fab lab I was able to create from scratch and laser cut a whole range of different patterns. Laser cutting was the fastest way of realising these shapes, you could also mill these patterns if you had a bit more time.

If anyone wants to make their own patterns like this, you can download the Inkscape plugin below. This includes descriptions of how to adjust all the parameters to create the pattern that you want.

Download Plugin | View Readme.txt

For those mathematical people out there who feel that I’ve left something out so far. Here’s actual maths to generate the basic fibonacci spiral patterns:

As polar coordinates each point’s angle is the golden angle further round than the last point. The golden angle is a full circle (360O) divided by the golden ratio; About 222O. The distance of each point from the centre is proportional the square root of the number of points so far. The amazing thing about this pattern is that fairly evenly distributes an arbitary number of points into a circular shape. This is the reason why it turns up in nature all the time, plants need to do this! To learn more, check out these links below:

How I Made Wine Glasses from Sunflowers by Christopher Carlson

Doodling in Math Class: Spirals, Fibonacci, and Being a Plant by Vihart

 

Three Foot T Rex

I was out drinking with some friends, shortly after learning how to use a Shop Bot CNC router. The next thing you know, we realized the little wooden models of dinosaurs we all had as kids Didn’t have to be so little any more.

T Rex at Fablab

This design has been around for as long as I can remember. The generous people at epilog are giving it away in their sample club. The design’s a little bit rough around the edges, but nothing a few hours can’t cure.

The time consuming part was modifying each slot to fit the 9mm birch ply I was going to use. This is harder than you might think! For the slots to fit together nicely they have to be within 0.2mm of the thickness of the board. Sheets of 9mm birch ply are usually between 8.6 and 9.4mm thick! So you have to buy and measure your board before you can finish the design.

I’m chuffed to say this OCD attention to detail payed off. This first set of parts slotted together like a dream first time!

T Rex hatching

For the full technical writeup on the Fab Lab forum here.

The Hillary Step’s Laser Cut Menus

In the autumn of 2011 I was commissioned to design and make a set of unique menu folders for the Hillary Step in Manchester. Three months later they had a beautiful set of 25 menus and a custom board to hang them all on.

hs menu - open front

The unique laser cut hinges are kept in place with friction. The final finish is a water repellent varnish and the paper inserts are held in place with an elastic thread clamped in brass tubing.

hs menu - shameless plug

The wall board for the menus was a new challenge for us to make. It is a combination of laser etched text on a  CNC routered board. Aligning the two processes on a single piece of wood was a new challenge for us, but was well worth the effort.

IMG_9487