My Summer Internships: A Retrospective

Yesterday I was thinking about all the wonderful summer internship experiences I had while at university. I felt bad about the effect of the COVID-19 pandemic will have on those currently studying who won’t be able to take up their internships this year. I thought I’d write down my own experiences to share, in the hope that it will be useful for someone planning their future adventures, in 2021 summer and beyond! 

My internships, 2001-2005

Summer 200110 Gresham St. Project, Bovis Lend Lease

In December 2000 I accepted an undergraduate sponsorship from Bovis Lend Lease (now Lend Lease), to do electrical engineering at university. The offer was independent of my choice of university, tied only to the subject. I had looked up undergraduate sponsorship options when I was 17 and thinking about university, as a way of reducing the costs and boosting my employment prospects. Bovis was the first company that I had applied to and I accepted without hesitation. I’d also looked at IBM for their PUE scheme, Microsoft and also some of the military/defence related options, but they had later deadlines and certainly at the time IBM didn’t commit to anything more than a gap year employment. The deal I was offered by Bovis included annual trainee conferences, some industry skills training at the CITB training centre in Bircham Newton and annual postings as summer holiday cover to construction projects in my area. In return I would receive a book allowance during term time and be paid as a junior site supervisor during my summer work. The programme still exists today, so definitely take a look if you are seeking undergraduate sponsorship for a career in construction!

Normally the programme didn’t start until the first summer of university, but I asked if it was possible to start on site directly after my A-levels and the company was very accomodating. I was sent as a junior to help out the building services team on the 10 Gresham Street construction project, which at the time was in the process of excavation. The building was to be a low rise office, designed by a team renowned architects Foster & Partners. My boss was Gary Sturges (Hello if you are reading this!), who was the building services manager for the project and started my education in what it is that makes a modern building light up! The services designs were a long way from installation, so I also got to follow some of the groundworks and steelworks. Being realistic, a fresh faced 18 year old can’t necessarily contribute a whole lot to a multi-million pound construction site, but here are some of the more concrete things I did included:

Learning how to fold a drawing and keep the site drawing sticks updated with the latest revisions. It’s basic grunt work, but having the latest revision of a drawing is fundamentally important.

How to work in an office! For the first time I wasn’t going to school every day, I was taking the tube into London like an adult. There were all kinds of things to navigate, including finding my way to the office on day one, finding my way to site thereafter, buying lunch from a sandwich shop. Using email for work, handling a photocopier and sending and receiving faxes (yes, faxes were still very much a thing back in 2001!) with cover pages.

After a month or so I had done the necessary safety training myself, called a ‘license to practice’ back then, and was authorised to give site inductions to visitors and some of the smaller or specialist groups of workers attending the construction site. I remain impressed by the commitment to safety on all the Bovis Lend Lease sites I visited and worked on, the process of giving these briefings gave me my first understandings of the statutory duties of employers to provide a safe place of work and a safe system of work for their employees. The other thing I learned is that safety works best when it’s a human to human interaction, knowing that before anyone steps out onto the potentially hazardous environment of a construction site, someone else has taken the time to explain the particular dangers of that specific site and to remind them that safety is a partnership between employer and employee.

I also attended my first work meetings, learning essential skills such as staying awake, followed by more advanced meeting skills such as taking and preparing minutes.

Finally, I had time to read the company site safety manuals and safety system. These were a couple of very large A4 ring binders with the distilled procedural knowledge of the company for how to run a construction site. They were a great resource and it was especially useful having the time to read through them – I often wish I still had a copy to refer back to even today.

 Bank of America European HQ

Summer 2002Bank of America fit-out, Bovis Lend Lease

After my first year of university, I went home for the summer and was soon commuting daily to Canary Wharf. At that time Bovis had a specialist fit-out division called Bovis Lend Lease Interiors who had won the contract to fit out trading floors. Initially I was based at their office in Farringdon, then as the project moved closer to the start date we relocated to offices in Harbour Exchange to be closer to the site at 5 Canada Square. The building for the fit-out was still in the final stages of completion by another contractor, so access on site was limited. During the summer I learned a lot about the importance of tracking document issues and revision by external consultants, as a key part of driving design towards something which can actually be built. I was given the ER’s to read (employers requirements), which was my first introduction to reading and understanding formal specification documents. This was the first time I had had the opportunity to work on a really complex electrical services installation, with a small data centre and dealer desks for financial trading part of the installation brief. I also had the pleasure of working for Denis Wilson (Hello Denis!) who was running the fit-out services team, and who would later be my boss again on another highly complex and challenging Bovis project over at the BBC.

Churchill gave his VE Day speech from this balcony.

Summer 2003 – HM Treasury Phase 2 PFI, Bovis Lend Lease

Following on from a challenging second year at university, I was assigned to a mysterious sounding project called “GOGGS East“. It was the second stage of the refurbishment of the UK Government Treasury office building in Whitehall, on the corner of Parliament Square. Here is a great presentation I randomly found online showing the insides of the building and some of the work, which is Grade II* listed, the highest category for UK buildings with historical and architectural value. The building has a rich history, including hosting significant fortifications installed during the second world war to bomb-proof the basement areas, where the cabinet war rooms are located.  One of the highlights of my internship was unlocking the Churchill Room, the majestic office used by Winston Churchill at some points during the war, with it’s balcony at the front of the building overlooking parliament and whitehall used for his speech on VE day. Another fascinating part of the building were the old treasury vaults on the sub-basement level, where some of the UK’s gold reserves were once stored. The gold was long gone and they were to be filled with concrete as part of the renovation.


Summer 2004 – I travelled round the world visiting lots of construction projects, funded by the Royal Academy of Engineering.

This is another story in and of itself, which merits a blog post to itself – one day I’ll try to write it. I was very fortunate to be awarded an Engineering Leadership Award in 2003, which gave me access to funding, a mentor and fantastic opportunities to expand my knowledge and skills. The program still operates today, and I cannot recommend it highly enough. If you are interested check out this link for details on eligibility and how to apply.


Summer 2005 – Summer student at CERN

I visited CERN for the first time in the summer of 1999 after persuading my parents to send me on a school trip. I really liked it and applied to return as an intern via the summer student program. Again this is a fantastic opportunity, I would recommend it without reservation to eligible students. You can check out the application procedure and eligibility requirements here. This internship was rather different from the others, with morning lectures on mathematics, physics and the challenges of building particle accelerators, visits to the then under-construction LHC and in between I worked on my project, writing a part of a detector control system for LHCb in VHDL. In addition to the huge intellectual stimulation, the career benefits, I made lifelong friends from across the world – many of whom I’m still in touch with, and some I work with on a daily basis! Back in 2015 we had a little get together to celebrate our 10 year anniversary, here’s what I wrote about it at the time.


These internships were a fantastic learning experience and set me up for my current career as an electrical and electronic engineer. I’m very grateful to all those who helped me to get them and to make them such valuable and rewarding experiences. While this year may be a wash-out due to the pandemic, there are still some fantastic schemes out there for current students and those applying to university this year. If you are a student I highly recommend seeking them out for next year!

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The Brexit Post (from 2017)

I wrote this post just over 3 years ago. It seemed too pessimistic to publish a the time. Now, in the midst of the pandemic as the UK government push hard for a no-deal outcome, we are reaching the end of a path littered with broken promises. I thought it was time to share.

17th January 2017

My country is sinking. The parts of the world that aren’t already on fire are about to be ignited. Here’s what I think:

The question which was asked of the British people on the 23rd June 2016 was:

The referendum question will be: Should the United Kingdom remain a member of the European Union or leave the European Union?

On the basis of a 52/48 split on a vote for leaving the EU, the UK Government is now pushing for a “Hard Brexit”. This means:

  • Leaving the EU (fairly obvious)
  • No freedom of movement (not obvious)
  • Leaving the common market (also non-obvious from the text of the question)

The destructive consequences which will result from taking the actions above include:

  • Loss of access to all EU research funding, which will decimate research and innovation in UK universities.
  • Loss of access to EU markets at current tarrif free rates, requiring complex negotiations to re-establish a worse deal.
  • Potential loss of access to all WTO deals until something is negotiated.
  • Subject to a deal being reached to allow them to stay, all EU nationals will have to leave the UK.
  • As part of the same deal, UK nationals may also need visa’s for future travel to the EU.
  • Farming will be heavily hit by the loss of EU funding, unless a timely and adequate replacement is set up.
  • Unless suitable legislation is enacted before we leave, UK citizens will loose all their current rights enshrined in EU human rights laws.

Furthermore, the government wants to do all these things without a parliamentary vote.

Failing to consult and gain approval from parliament for the above would be a brazen action, putting at risk the rights currently enjoyed by british citizens. If we are to have a significant proportion of our existing rights removed without parliamentary vote, it would be an extraordinary situation. Abrogation of the rights of the citizenry without the consent of their representatives is clearly morally wrong. Abuse of power in this way is the road which leads to tyranny.

Post Script

That was what I wrote three years ago. It seemed too depressing, too pesimistic and yet here we are. The government has sought to shut down parliamentary scrutiny of the Brexit process, and was ultimately found to be in breach of the law. Any who urged caution, real negotiation with the EU and the path of moderation from within the Conservative party have either been chased out or formally purged. In the context of the pandemic, the UK government has been using secondary legislation, without any parliamentary scrutiny, to restrict the rights of UK citizens in quarantine. Now established, I fear that these habits will be a hard for the government to break.

If there is light, it comes from the devolved nations, Scotland, Wales and Northern Ireland. When the dust settles, I am sure the statistics will show they have thus far managed the pandemic far better than England. Scotland in particular has stood firmer against the prevailing winds of political change, the chilling of discourse and has remained vocal in welcoming those from foreign countries. It shows that the downward spiral of Westminster politics is not the only route available, we shall see what the next three years bring.

Building a PV Microgrid for the Druk White Lotus School, Ladakh, India

I’ve been very priviledged to have worked on some great engineering projects in my career to date. This blog post is about one of the stand-out projects that I was fortunate enough to work on while at Arup in London, back in 2007 and 2008. The Druk White Lotus School is an exemplar sustainability project, located in Ladakh, India.


The start of the school day at the Druk White Lotus School

The Druk White Lotus School is a boarding school in the foothills of the Himalayas which aims to foster and preserve the unique culture of the Ladakhi way of life. The school is planned based on the Dharma wheel, with classroom buildings near the entrance, and residential blocks further back within the site. It was my role to work with the client in developing the technical specification for the microgrid installation and to support them during the tender process, then at the end of the project I had the chance to go to Ladakh and get hands-on with the final commissioning and site acceptance testing in September 2018! Ladakh has a harsh climate, with extremes of hot summers and freezing winters, which was one of the drivers of the project schedule. The treacherous road to Leh closes for winter, restricting the availability of building materials. Due to the cold winter temperatures all building work outside is very difficult, meaning that all work had to be completed before the bad weather set in.


A Sand Mandala, inspiration for the layout of classroom areas of the school. (image taken by Colonel Walden, from Wikipedia, CC BY-SA 3.0)

The Leh valley, where the school is situated has an intermittent electricity supply, with a typical maximum of 4-6 hours of electricity per day (at the time of construction). Electricity was rationed, based on different districts and areas, not conducive to a school lesson plan using computers or electrical equipment of any kind! The design of the Druk White Lotus School has been supported by Arup on a pro-bono basis since the inception of the project. The installation of an on-site micro-grid, with solar panels and battery storage was designed to permit the site to operate automonously, with a top-up from the grid supply when available.


The school is located in a stark and beautiful valley.

One of the main challenges of the project was to install a distributed generation and electricity storage system on top of an existing electrical infrastructure. As school buildings were constructed, each was added to the three phase low voltage electrical network via copper or aluminium cable. Each building had a local single phase distribution box (or fuseboard) to supply interior lighting and sockets. The site was also equipped with a very small back-up generator, feeding in to the local distribution via a break-before-make transfer switch. A further constraint for the design was the requirement to construct a modular, scaleable system that would be able to grow with future development of the school, as new classroom buildings and accomodation blocks were added.

Untitled Diagram

A block diagram for the system as installed, arrows denote energy flow.

The system architecture is shown above, with three single phase PV installations added to the three classroom buildings at the front of the mandala site layout. Sunny Boy PV and Solar Island battery inverter systems from SMA were specified for the hardware installation,  The angle and orientation of the PV installation was optimised using the freely available RetScreen software. Each was connected to a different electrical phase, providing an overall three phase balance for the site, via the existing distribution system. A new power house building was constructed to house battery storage and three single phase battery inverters with a common DC bus. The existing AC disrtibution system wiring was retained, with frequency modulation used for communication between the battery storage and distributed solar inverters, located approximately 400m away from the power house building.


The contractor team, one of the site supervisors and me in the battery house towards the end of the project, September 2018.

System functionality:

  • Self-contained micro-grid, capable of autonomous operation on PV supply
  • Phase-Phase energy transfer via DC bus for unbalanced loads
  • Energy storage via lead-acid solar batteries designed for deep discharge operation on a single DC bus
  • Ability to perform battery charging and operation from local generator (recommended for periodic full recharging of the battery system as a maintenance operation)
  • AC distribution frequency modulation used by SMA inverters for communication without the need for additional communications wiring, using a slight lowering of the micro-grid frequency to encourage PV supply, and a frequency rise to disconnect PV supply in the case of insufficient demand and/or a fully charged battery.
  • Potential to sell energy back to the grid, however this was disabled at commissioning due to the lack of a regulatory/legal framework in the local energy market.
  • Sunny Island inverters equipped with SD card slots providing minute by minute logging for easy remote analysis of the system performance.
  • 9kWp PV installation, in three modules of 3kWp per building.
  • Capability to add additional PV installations on future buildings.
  • Capability to add additional battery capacity as funding becomes available.
  • A new earthing point was installed for off-grid operation.



Construction of a new earthing point for the site

The site commissioning process was very challenging, as it was the first installation of it’s type for all those concerned (contractor, site foreman and myself the design engineer), there were also significant differences, both in terms of culture and electrical installation safety standards to be overcome before the system could be commissioned. It was also necessary to borrow the only three phase rotation meter in the valley from the local airport electrician in order to ensure the correct configuration of the three phase system. The only major issue with the commissioning came when the battery system was fully operational and charged, with the solar inverters failing to connect. Upon further investigation, it transpired that the solar inverters had been shipped with firmware settings for domestic installations in Germany, rather than the micro-grid firmware required in this installation. A laptop with the new software and a suitable communication interface had to be flow in to Leh in order to make the upgrade, but once completed in October 2018 the system performed as designed.


The Sunny Boy solar inverter installed within the vestibule space of the classroom buildings, complete with PV isolators, mains isolator and an energy meter to monitor power generation.


This was a wonderful project to work on back in 2008. The challenge of designing a micro-grid system for a self-contained school, building upon existing low voltage distribution infrastructure in a remote location was significant. Then the opportunity of getting hands-on for the project commissioning in such a unique environment was possibly a once in a lifetime opportunity. Having all the system performance data logged to SD card was also very helpful in supporting the installation when I returned to the UK. Receiving the call from site in October 2008 to hear that the system was working as expected after the firmware update was a real moment of both relief and excitement.

If you would like to know more about other aspects of the multi-award winning Druk White Lotus School project you can find additional details in this article in Ingenia magazine.


PV panels supported on wooden trusses which form part of the classroom building structures.

Post script: At the time I had the idea of filming various critical operations on the system and putting the videos on YouTube for future reference. This was really useful and something I would highly recommend for anyone doing this type of project! The videos are still online, you can view them here in this playlist.

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Build your own CPU with RISC-V and a Lattice ICE40 FPGA

I’m giving a workshop next week on how to build your own RISC-V CPU within a Lattice iCE40 series FPGA using the awesome Icestorm framework by Clifford Wolf. We need two toolchains here in order to create both the processor and the code to run on it, and we will build EVERYTHING here from source. You can download the VM here– which obviously you do at your own risk, you should abide by all the relevant license terms, and you should really use only for educational purposes.


Stage 1: Create a VM

The main issue with running up your own RISC-V cores is having the toolchain ready to go. So I’ve created an Ubuntu VM, based on 18.04 minimal and running within Oracle VirtualBox. I chose minimal because it’s lightweight, small and will have a reasonably manageable footprint when putting the VM on a USB stick, and because Ubuntu is my native Linux distro. The choice of VirtualBox was down to it’s cross-platform compatibility and the fact that it’s free to use. The VM is configured for 4Gb RAM and 30Gb HDD, AMD64 CPU, with nothing fancy on top. In order to facilitate cross platform compatibility and carrying it round on a USB drive, I’ve also set the HDD to be split across 2Gb files, since some file systems have a restriction on the maximum size of a single file. The total size of the VM comes to >17Gb, so make sure you have plenty of hard drive free!

I created the username “risc” with the password “Lattice”. I don’t generally advocate writing your username and password on a blog, but this is a special case. Evidently don’t leave this VM running, or give it open ports to the outside world when you are using it!

Stage 2: Configure the VM

Once the VM has been setup, it’ll need the icestorm toolchain installing in order to program the FPGA. This comprises a number of things in more or less the following order:

stack for fpga

1. FTDI drivers from here. It’s a .tar file, so you’ll need to unzip it a couple of times and then follow the instructions for how to copy the driver files in to your system directories as a super-user.

tar xfvz libftd2xx-x86_64-1.4.8.gz
cd release
cd build
sudo -s 
cp libftd2xx.* /usr/local/lib
chmod 0755 /usr/local/lib/
ln -sf /usr/local/lib/ /usr/local/lib/

2. Packages to make everything work in Ubuntu (note I’ve added libeigen3-dev, not included on Clifford Wolf’s page, since I needed it):

sudo apt-get install build-essential clang bison flex libreadline-dev \
                     gawk tcl-dev libffi-dev git mercurial graphviz   \
                     xdot pkg-config python python3 libftdi-dev \
                     qt5-default python3-dev libboost-all-dev cmake libeigen3-dev

3. The Icestorm toolchain components from here:

4. A sample program to check we’ve got the FPGA compilation working, before we move to RISC-V compilation, from here. I cloned this code into a directory called flash, compiled it and uploaded it to my device to make it flash the leds in sequence. It worked first time, after I connected the USB device to the VM.

It’s worth noting at this point that I haven’t installed Icarus Verilog, since it isn’t strictly required to compile to the target, but would be needed if we wanted to test things! If I get time I’ll add it to the VM. Thanks to Oliver for pointing out this nice FPGA toolchain installation script.

UPDATE: I just added Icarus Verilog (V10) built from source and the Icicle repo for some better Upduino support. The Icicle serial output doesn’t seem to be working when flashed to target, but it does make the LEDs light up on the iCE40HX8K and Upduino boards. I also added minicom and picocom for serial monitoring.

Stage 3: RISC-V

Now that we’ve got a working toolchain for the FPGA, we need to build a working RISC-V compiler in order to have code to run on our chip. I installed Clifford Wolf’s Picorv32 from here. This basically takes you to the RISC-V mainline toolchain and picks out a particular revision and only the compiler required for smaller/less capable cores. When compiling it for the first time, I was stuck for a few hours on the ../configure line pre-compile to insure that the /opt/riscv32i toolset is used (the other toolsets are not compatible with the iCE40HX8K FPGA due to size restrictions), but eventually figured it out.

What we are actually building in this stage is an add on for GCC that will enable us to compile binaries for execution on our soon to be created RISC-V core. There’s no point having a CPU if we can’t aslo compile code for it from a high level language.


RISC-V implementation on iCE40-HX8K, image taken from the PicoSoC presentation given by Tim Edwards, Mohamed Kassem and Clifford Wolf at the 7th RISC-V Workshop, November 2017.

I followed the instructions in the picorv32 repo as follows:

git clone picorv32

sudo apt-get install autoconf automake autotools-dev curl libmpc-dev \
        libmpfr-dev libgmp-dev gawk build-essential bison flex texinfo \
    gperf libtool patchutils bc zlib1g-dev git libexpat1-dev

sudo mkdir /opt/riscv32i
sudo chown $USER /opt/riscv32i

git clone riscv-gnu-toolchain-rv32i
cd riscv-gnu-toolchain-rv32i
git checkout 411d134
git submodule update --init --recursive

mkdir build; cd build
../configure --with-arch=rv32i --prefix=/opt/riscv32i
make -j$(nproc)

Stage 4: Hardware

Now the software is all ready to go, we just need a hardware platform to run it on.

This tutorial is designed to run on one of the following demo boards:


The Lattice iCE40-HX8K evaluation board, available from Digikey.


The UpDuino, available from GnaryGrey.


And the BlackIce II designed by a couple of awesome guys in the UK!

Stage 5: Compile and upload

Everything is very nearly finished. Except it doesn’t work just yet. We also need to install the VirtualBox expansion pack in order to access USB2 devices. We can download it here and add it via the GUI.

Then we need to ensure that we can find the compiler for RISC-V, which we can do by adding it to the PATH environmental variable:

export PATH="$PATH":/opt/riscv32i/bin

If you fail to do this, you’ll get a tonne of “riscv32-unknown-elf-gcc command not found” errors until you correct it. Make sure you don’t wipe out the path variable in the process!

And just to make sure we can access the device, let’s add our user to the dialout group:

sudo usermod -a -G dialout risc

With all of this in the bag, we need to ensure that our VM is connected to the USB hardware, which we can do via the menu or the USB attachment icon in the bottom right of our VM window. We should enable the Lattice device, and then we can complete our build and upload with the following commands:

cd /picorv32/picosoc
make hx8kprog

If everything works as it should you’ll see various messages about compilation and programming of the device, followed by “VERIFY OK cdone: high… Bye.”. The LEDs on your board wil blink about once a second. Note that there are several options for alternative things to do in the /picosoc directory, all without yet writing your own code or core, they are detailed in the makefile in the picosoc directory which is definitely worth reading.

It’s worth noting that I couldn’t get my permissions quite right so I had to cheat a little for access to the USB device to do the final upload, but calling make hx8kprog as sudo. Not the best technique, but it worked!

Conclusion – Testing the CPU

At this point I chose to unplug my FPGA dev board from the virtual host and hook it up to a real one (with the drivers installed of course!) to check that I’d actually built the core and it was working properly. I launched my trusty Arduino IDE and fired up the serial console, baud rate 115,200bps on the correct COM port and was greeted with this:


We have now built a working RISC-V core on our FPGA board and programmed it with some compiled code. I’d like to thank the awesome Clifford Wolf for basically making it all possible (he wrote the core we used to implement RISC-V and the ICESTORM toolchain we used to generate and upload our bitstream) and RMWJones for posting some very useful scripts that helped me along the way.


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MQTT and Round Robin DDNS

Last weekend I set up a round-robin DDNS system for internet connected Cosmic Pi devices. Here’s how I did it, but first let’s find out why this is useful.

For Cosmic Pi we’re trying to build a scalable, global infrastructure for cosmic ray detectors to connect to. We don’t want to reinvent anything, just to use a suitable existing technology. This is where MQTT comes in, it’s perfect for our use case. With one or two brokers, we can connect many clients and everyone can share the data. We could even use topics for remote configuration messages, but that is for the future. For reference, our MQTT journey started with RabbitMQ and we’re using Mosquitto these days.

As a figure of merit, a Mosquitto MQTT broker can cope with 1000 publishers or subscribers. I read this on the internet, I’ve no idea how true it is at the moment. 1000 isn’t a large number for a global cosmic ray telescope, so we need to add more capacity.

We also don’t want a single point of failure. The broker has been running on my home server for the last year, which is great for testing but not exactly high reliability territory. So figuring out a way to have two, parallel and synchronised brokers would be an ideal solution to scalability and reliability, enter round robin.

I’ve been using DDNS (Dynamic Directory Naming Service) for a while now to get remote access to my home servers. For those unfamiliar with the service, it allows you to associate a domain name with a dynamic IP address (V4) and update it every time your IP changes. So (for example) always points to your home IP, even if your ISP changes it. Of course a local client of some type is needed to ensure changes get propagated to the DDNS servers, but fortunately many routers (especially those running DD-WRT) support this out of the box.

Originally the service for Cosmic Pi MQTT ( used a single DDNS hostname linked to one IP. To implement a round robin using the excellent free service provided by, all you have to do is create a second sub-domain with an identical name and link it to a different IP. Round robin requests are handled automatically, so the first request gets directed to IP address A, the second request to IP address B and the third to IP address A etc. Of course fail-over in this scenario relies on the client detecting a server failure and requesting a fresh connection, but this is not an unreasonable expectation. If we lose a few cosmic rays it’s not the end of the world as long as the service stays available.

Once two MQTT brokers are running on each of the IP addresses, only one more issue remains. The MQTT brokers must be linked, otherwise what happens on server A stays on server A and the same for server B. Fortunately Mosquitto makes bridging easy, but we have one more hurdle to overcome first.

In order to bridge the two MQTT brokers, one must be able to refer to the other by a unique DNS name (i.e. can’t be used as it alternatively points to both servers). We could do a little bit of script magic to ask for both IP addresses, then sort out which one is the remote server, but amongst other things both servers are behind NAT (network address translation) so a third service would be required to resolve the internet facing IP for the local host. The solution I implemented was to simply have a second unique DDNS name for each server, which is kinda handy anyway if you want to SSH for remote administration. Under this configuration, we can explicitly bridge either server A to server B (or vice versa) without introducing any dependencies on additional services.

We now need to add a bridge command to server B so that messages it receives are shared with server A, and that it also subscribes to those messages being received on server A. In this way both servers have a complete copy of the data at any time. If server A goes down, the clients will eventually (depending upon the timeout we’re looking at milliseconds to minutes) request an update from the DNS server and end up being connected to server B. It doesn’t matter too much what happened to server A and the bridging, because server B will now be getting all the messages anyway.

This method has limits, specifically if all users are switched to just one server it must be able to cope with the demand, i.e. we are probably fine for 500 users on each server. I’m not sure why or if it’s possible to bridge multiple servers beyond two, I couldn’t find any examples. If we end up with a lot of Cosmic Pi units out in the wild we will find out!

If you want to try the MQTT service running for Cosmic Pi you just need to get an MQTT client and connect to on port 1883, then subscribe to # for all the messages!

Open Auto (an adventure in open source, open hardware community car sharing)


Just over a year ago, I attended a Geneva Smart City hackathon at the HP campus in Meyrin. I confess that my primary motivation for attending was to see inside the HP office, because I was curious! I brought with me a couple of Dragino LoRa expansion boards for Raspberry Pi and I pitched the project of creating an easy ‘how to’ guide for people looking to set up their own LoRa networks, mostly because it’s something I’ve wanted to do for a while and haven’t gotten round to yet – and because I think it would be very useful for many open source, open hardware, smart city projects. It turns out that The Things Network has actually made some great strides in this area since (and probably even before) – worth checking out for your LoRA projects. Nobody was interested in my pitch, so I went and joined a team of people with a problem who were looking for a solution.


At the time the project was called Open Auto, but it’s now morphed into Comobilis. The aim of the project is simple, to build an open infrastructure for community car sharing. This particular post is about a hardware platform for community centric car sharing. It’s not a box designed to allow you to share your car with random strangers, like airbnb for cars, because I’m not convinced that’s such a great idea.

Time for some hardware!


If you’re going to share cars, you will need hardware. The main driver is a way to open and close the doors securely. This means hardware, and software. You can put the keys inside the car, you can put them behind the sun visor, you can chain them to the seat if you want. What is important is making sure that the car doesn’t need ‘undue’ modification – we’re not car hacking here (yet).

The simplest solution which works for most modern cars is to borrow the RF transciever from the keyfob. With a little bit of soldering, this can be wired up to a couple of relays to simulate a human pressing the open and close buttons. This provides a near universal interface for the car, which is as physically secure as the original key transmitter. In the future, it should also be possible to open and close the doors via CANbus, however a lot of manufacturers keep this information secret, as you could use it to steal cars rather easily.

The other required hardware items are a GPS to locate the car, and potentially track it in real-time (or check if anyone is speeding – it’s certainly possible, if not yet implemented), an RFID reader to allow the use of pre-registered tokens to trigger the door opening and closing, and an accelerometer, to allow the driver’s behaviour to be modified (it’s a great way to see if they are Driving Miss Daisy or driving like a bat out of hell).  To complete the system, we need some communications devices, including a CANbus transceiver, which can be used to read and write to the car bus (if we feel the need to) via the OBD-II port which is mandatory on all modern cars sold in Europe, a way of powering everything from the car’s 12V battery – conveniently also provided by the OBD-II port, and a means of wireless communication with the outside world.

After briefly flirting with the idea of an Orange Pi Zero and a 3G dongle, we settled on the Particle IoT ecosystem, specifically the Electron module. This provides a 3G modem and STM32 microprocessor, complete with a cellular data contract, management platform and Over-The-Air firmware upgrade capability (the last part is very useful, meaning that you don’t need to plug into each car to fix bugs or add new features).

Designing a board

All this hardware could be integrated, more or less onto a single printed circuit board. Here is the first attempt, complete with some assembly comments from Seeed Studio who built it:

open auto v1

Version 1 being assembled.

The downside of carrying round a linux box in your car is that it needs regular patches to keep it secure. These can run to tens of megabytes a month, which could be expensive on a 3G data contract. I was also concerned about the stability of the system, given the high temperatures that occur inside cars during the summer (such as today, where it’s 30 degrees outside here in Geneva and probably over 40 inside every car in the car park). The Orange Pi Zero is very cheap, however there have been some reports of thermal issues – so putting one inside a car and relying upon it to open the doors is probably not the smartest move. The PCB also had an issue with the pinout of the 5V to 3.3V level converter, which was pinned out incorretly as I didn’t read the data sheet thoughrouly enough. You can find the hardware (Eagle) for the first prototype here.

After some testing with this board (and also realising what a pain it was to prep OS cards for the Orange Pi Zeros), we decided to take things a stage further with a new design. The major flaw in the inital design was the use of an on-board GPS antenna, which failed to acquire any signals – making it rather useless. You will see that I included a footprint for an external GPS antenna on the V1.2 board as a reaction to this.

Re-designing a board

openauto design


Version 1.2 being assembled.

The new board was designed around the Electron and Photon modules from Particle, inspired by some work we saw from The use of the Electron allowed us to power most of the board from it’s Lithium Ion battery, however in the first production run the relays (for opening the doors) were still driven by 5V – I’ve since found a 3.3V relay, and the board is equipped for this with a jumper to switch the supply, so future versions won’t need the car to be providing +12V in order to open the doors.

The Bill Of Materials (BOM) for the PCB includes everything needed to assemble the PCB, which is a relatively simple 2 sided design. There are some optional components not included such as the SMA jack for an external GPS antenna which you may want to add if this is something you are looking for. In addition to the board, you will need a CR1220 lithium cell to power the Real-Time Clock and an RFID reader module (it was designed with the 5V RDM6300 or the 3.3V SEEED SKU 113990041 module in mind, there are also several equivalent 3.3V UART RFID readers at 125kHz available from places like Sparkfun or Aliexpress.

I initially started using the board with the key fob to my own car (an old but reliable Peugeot 307), which happens to carry the key battery on the key PCB. It turns out that most other cars don’t do this, using the plastic key casing to accomodate the battery – so for these it’s possible to jumper the 3V non-rechargeable lithium cell on the board to supply the key.

For the next version, since everything was more contained, I designed a case to go around it. The case material is laser cut acrylic, since it was cheap and allowed you to see inside the box, which I think is cool!


An assembled case with the brown paper still attached.

All that was left was to put it all together in the box and start writing some software. Oh and of course test the circuit board! It worked as expected, with only one small snag in the first production run – a missing connection between the I2C SDA and SCK lines from the Particle boards to the RTC and Accelerometer.


The finished article! Version 1.2.

The picture above shows the completed box, fully assembled with an electron module and the RFID card reader module + antenna. In fact this configuration has since been modified to rotate the loop of the RFID antenna away from the GPS as it was causing interference. Moving the antenna totally out of the box is on the to-do list for future versions.

The design files for the Version 1.2 unit are available here, complete with the case.  The software remains a work-in-progress. The hardware is fully open, licensed under the CERN Open Hardware License V1.2. You can find a relatively recent sketch here. Of course this is only part of the solution to community car sharing, it’s necessary to have a back-end which can host reservations, billing and user information, co-ordinate with the vehicles to make sure they are in the right place at the right time and allow a way to sign up new users. The Comobilis team are using Odoo, an open source ERP and PLM platform to build free extensions to connect to the hardware and provide the necessary software and interfaces.

Comobilis Logo final single_with tagline

If you would like more information on this project please drop me a line or check out where you can find out about starting your own car sharing co-operative. The co-mobilis initiaive is initially focused on Switzerland, but the hardware will work anywhere there is 3G signal.

In the present I’m working on adding more functionality to the firmware, completing the way reservations are handled and retrieved to allow people to actually use the vehicles, as well as things like GPS position logging, acceleration and clock functions. In the near future I hope to look at using ESP32 + Lora as an alternative to the Particle modules, taking it closer to the project that I originally pitched! I have also started a company to sell these boxes (and some other exciting open hardware electronics) with some friends, but that will have to be the subject of another post.

How to: Manbrain


I’ve been talking with by better half over the last few weeks about a revolutionary concept in the workplace. It has the potential to increase your effectiveness in the workplace by something between 0 and 100%. It’s the essence of learning to think like a man, that half of the species which has dominated the workplace since the term workplace was invented. So this blog post is probably going to be more useful to those who identify as women, but you never know. I would also like to point out for the benefit of anyone who is exceptionally stupid that this is supposed to be humorous – I don’t really advocate treating women as objects, starting physical fights with managers or the hero-worship of whoever has the biggest one. What is true is that Humans and Monkeys share 96% of their genetic material

To keep things simple, I will outline the 10 simplest rules of the Manbrain.

Rule 1: Keep things simple.


Manbrains are not sophisticated (for sophisticated see Womanbrain). The best way to imagine how they work is shown below, input, process, output. Action generally equals reaction, except when it doesn’t. The Manbrain is rather like a computer in this respect, invalid inputs (anything with an overly emotional, complex or unwelcome content) will be ignored. Inputs delivered in squeaky voices (womanspeak) are also likely to be ignored.


Rule 2: Shouting.

The Manbrain has been tuned by thousands of years of evolution to perform the function of listening. However this is heavily spectrum dependent and is geared towards the lower frequencies of human vocal communication. If you speak squeaky (high pitch, high tone) you will be ignored by the Manbrain.


The best way to communicate with the Manbrain aurally is to do so in deep, booming tones with a slow and regular cadence. You might find it helpful to imagine yourself as a large gorilla when doing this.


Rule 3: Bigger is better.


Manbrain evolution is also heavily focused on being bigger than everyone else in the one area that counts. The key driver is having the biggest one. Whatever that might be, and however it is defined. Manbrain pays attention to the person with the biggest one (the leader). Anyone who doesn’t have the biggest one is small, and therefore irrelevant. Manbrain seeks to make sure that its own one is as big as possible. Manbrain respects others based exclusively on the size of their ones.

Manbrain spends a lot of time thinking about how big it is. Other considerations, such as talent, intelligence, authority and capability are often (but not always) ignored. The one with the biggest is the boss, the boss man, the king, the leader, the head of the tribe, the smartest Manbrain in the social unit, or whatever other great title you want to bestow upon them – I personally like the title chief monkey, and also monkey chief. If you’re going to say it out loud, especially in the presence of the chief monkey, it had better be nice! Otherwise, they will be angry with you (see Emotion). If your tribe subscribes to corporate culture, the one who thinks they have the biggest one might be called a senior manager. Don’t forget that in corporate culture, those who stick around seldom ask questions, such as “Is the senior manager is actually the best Manbrain for the job?”, or “I’m not convinced by your Manbraining. How big is it really?”. This is because the answer is normally that they probably aren’t and don’t. Of course, if you don’t have a big one, you can substitute with a combination of nice toys, a shiny car and an expensive looking woman.


Rule 4: I am the best

Manbrain is very good at ignoring. That’s why Manbrain controls the world. In Manbrain there is no such question as “Am I good enough for this?” or “Will they consider my input as relevant?” or even “Perhaps there are better people for this activity than me?”. Manbrain is always the best.


Rule 5: Ignorance is no barrier to success


I have succeeded despite not knowing things in the past. Therefore knowledge is semi-irrelevant. Facts, could be known ahead of time, or we could just discover them as we go along! We will figure it out. I can do this, because I have Manbrain, and it’s very big, and you are going to help me, because I say so loudly.


Rule 6: I want that, because you have it.


It’s worth remembering that Manbrain is very similar to Monkeybrain. Monkeybrain is marginally less sophisticated (not as good at video games, vocal communication or delayed gratification), but otherwise a great analogue. Sometimes a Manbrain sees something that somebody else has (it could be a shiny new toy, or food, or an expensive looking female) and Manbrain wants to take it away from the someone else, either to enjoy or just to throw away to show the other person who has the biggest one.


Rule 7: Emotion


Emotion is simple in the Manbrain. It’s either Angry, or it isn’t. When Manbrain is angry there’s always someone to blame. Usually it’s another Manbrain who is guilty of the crime of “stupid”. Sometimes this might be the Manbrain with the biggest one. In corporate tribes, the reason for angry emotion is usually a phenomenon called ‘management’, which requires the performance of pointless tasks in order to gain a monthly bag of nuts and berries which can be traded for toys, food or other essential services. Sometimes there’s an emotion called sadness, which is basically the opposite of angry, but sometimes has the same physical manifestations. Sad is highly complex and way out of the scope of this article. If you have a Manbrain and think it might be suffering from sad, try pretending to be angry until it goes away, or you could pick a fight (see Rules 8 and 9).

If you are feeling an emotion that isn’t angry (or sad) then you are over thinking.


Rule 8: How to fight (if you have a big one)


Instant fighting is best done in the open, in a meeting, by shouting and banging the table with your fist. This is how to communicate with the Manbrain that emotion has happened. When emotion happens rapidly, it can overwhelm the Manbrain and starting a fight is the only way to regain control. Just like when an excess of heat and fuel combine to create a fire, which incidentally is a reliable way to tidy up your Mancave or to cook food.


Rule 9: How to fight (if you don’t)


If you think that the person you want to fight has a bigger one than you, or more friends in the tribe, you shouldn’t engage in direct confrontation. Instead you will need to build your own secret tribe, and then when the time is right you should strike. Alternatively, just find someone higher up the tree and offer them a bribe in order to do your fighting for you. The bribe might be loyalty (because everyone else in the tribe is stupid), nuts and berries (this is very crude, even for Manbrain), or occasionally useful information which the Manbrain might be able to use to win other fights, or to exchange for more nuts and berries elsewhere.


Rule 10: Not taking anything too seriously.


In order to keep your Manbrain in good condition, it’s important not to get too stressed. Stress has a negative effect on your ability to Manbrain, and thereby solve problems and command others with your Manbrain skills. If you follow the rules, simplicity, shouting, respecting and searching for bigness, total self-confidence and mastery of emotion (anger, everything else is stupid), then you will be a highly successful Manbrain. You might even be the leader of a tribe one day (regardless of your suitability or even the size of your one)! You’ll certainly do better than anyone who doesn’t have a Manbrain.


In summary, it’s a jungle out there! If you didn’t have the good fortune to be born with a Manbrain (or even if you did), reading this article and using your imagination might help you to succeed in your tribe. Having been part of many tribes over the years, I have known many good chief monkeys  (and some good monkey chiefs!) as well as some totally useless ones too.  Understanding how Manbrain works has definitely been a common characteristic of the best chief monkey’s (both male and female) I’ve had the pleasure of banging rocks together with. Good luck Manbraining.




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A van pulls up outside of your house. Three men in uniform get out and come to your door. They say you have to go with them, because you are an illegal immigrant. They put you in the back of the van and drive you to a detention centre, where you will remain until you are flown to a country you barely know.

But you aren’t an illegal immigrant. You are a citizen.


I’ve been reading about the Windrush scandal for a couple of weeks now. It blows my mind how cruel, out of touch and incompetent the British Government can be – to its own citizens.

Let’s be clear about some things:

  1. We’re talking about individuals who were in the UK legally.
  2. They weren’t always able to provide proof they had been in the UK for the required duration because: a) The government destroyed a significant amount of the records, b) the government wasn’t accepting government issued paperwork, c) public sector workers in charge of administering the system had been specifically instructed to make things as hard as possible for the applicants.
  3. Legal aid budgets have been savaged since 2010, making obtaining subsidised legal advice a virtual impossibility for anyone who isn’t “rich”.
  4. Appeals were systematically rejected by the Home Office, regardless of legitimate grounds such as the right to a family life, under the Universal Declaration of Human Rights to which the UK is party.

There’s no world in which it’s OK for governments to send out vans of uniformed men to detain and deport their own citizens. These actions were illegal and have caused untold human suffering to as yet uncounted hundreds and perhaps thousands of British citizens.

Call me naive and idealistic, but the government makes the law. In this instance the government broke the law. Governments are also supposed to act in the best interests of their citizens, which is the exact opposite of what happened in this case. When laws are broken there should be some sanction against those individuals who break them, and when democratically elected governments act against their citizens those governments fall. But this isn’t the end of the story.

A report by the Electoral Commission published late last year suggested 3.5 million voters (7.5 per cent of the total electorate) would have no valid form of photo ID.

Legal aid restrictions have cut access to the justice system. Voter ID, being rolled out in the UK next month in a few pilot areas, is about to do exactly the same for democracy. If 3.5 million citizens are denied the vote, everyone loses.

I’m no statistician, but even a government minister can see that 1) The groups most affected by the illegal deportations of the Windrush scandal are disproportionately black and poor and 2) The groups most threatened by Voter ID are disproportionately poor and black (don’t just take my word for it, that’s from the UK Equality and Human Rights Commission in a leaked letter to the government). All of this is out in the open now, thanks to some persistent and brave journalists, but so far it looks like nothing is going to change.

What’s next for the UK? I don’t know, but it it’s not good…

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Places to go drinking (and a few other non-alcohol based activities) in Geneva

It’s been a while since I updated my ‘things to do in Geneva’ list, I have a friend visiting this weekend so now is a good time.

Where to start? La Petit Reine!

It’s right next to Cornavin station. Wrap up warm as the inside is tiny so you’ll probably end up standing outside. If it isn’t too busy, check out the upstairs for a tiny little room that sometimes has a DJ. What to drink? They often have beer from La Nebuleuse or Pere Jakob on tap. They do a few bar snacks but it isn’t great for food. A good bonus upgrade for your pint is the shot of ginger cordial, if you like ginger. The vin chaud is also a great call in winter.

Next – It’s only open on Saturday mornings and a long way from anything, but Pere Jakob is definitely worth a visit.

Pere Jakob is a micro/mini-brewery located in the Geneva countryside. They only sell beer by the bottle (and there’s a 10 CHF deposit on the bottles + the cost of the beer), but you can do free tasting on site, Friday evenings and Saturday mornings. Normally they have Blonde, Ambree and Blanche available, all organically produced.

If you fancy a cocktail (which are pricey in Geneva) I would recommend:

  1. Le Verre A Monique – Great when it’s quiet, vintage glassware. Can get SUPER crowded on Thursday/Friday/Saturday, especially later.
  2. Barbershop  – Just round the corner from Le Verre A Monique, comic book decor and a more relaxed/bar type atmosphere. They also serve a good selection of food.
  3. Atelier Cocktail Club – Over in Eaux Vives, classy and a good selection of cocktails.

If you’re in the Eaux Vives neighbourhood you should also check out Yvette de Marseille, a great little bar just round the corner from Atelier Cocktail club. It’s a friendly place that’s quite large so room for a group of people. I think they also do food…

Another favourite of mine is Cafe Remor, at the point of Plainpalais. It’s a great place for a quiet drink of beer or wine, they do good food, excellent ice cream and nice mint tea.

If you fancy a non-alcoholic drink I would recommend Gilles Desplanches at Molard for hot chocolate and cake.

There are a lot of expat bars in Geneva, they tend to be pricey and full of English speakers. The advantage is that you can order in English and watch international sports. Here’s a run-down in order of my preference.

  1. Lady Godiva – at the other end of Plainpalais from Remor and just a little round the corner. Good pub quiz on Monday evenings. It’s not cheap. Good food.
  2. Pickwicks – overpriced beer, plenty of space, it’s in a basement though so extremely dark. Slightly less good (I used to go there when I first arrived) pub quiz on Monday evenings.
  3. Britannia – Opposite Cornavin. It’s like a lounge inside. Not really the place for a rowdy night of drinking.
  4. Lord Jim – I think I’ve been here once?
  5. Les Brasseurs – Basically it’s an ex-pat pub. Overpriced beer, but a great location facing the main station.
  6. The Clubhouse – I went there once. It was noisy. The beer was expensive. I didn’t like it.

Finally, some other places which don’t quite fit into any of these categories:

Brasserie du Molard – a microbrewery, sometimes the beer is good, sometimes not so great. They do a good flammekueche. Also not to be missed is Pizzeria Ristorante Molino next door, great pizza (but fairly standard Geneva prices).

Brasserie Lipp – it’s a restaurant that’s big, open on Sunday, and you can probably get a table without a reservation so long as it isn’t peak time. Great for seafood, excellent mille-feiulle.

Spring Brothers Irish Pub – I’ve only been here once or twice since I used to frequent it as a summer student in 2005. It’s a really interesting building in the old town, consisting of several houses with interconnections through walls. The vaulted basement is also very cosy. Great Guinness, as you would expect. They also often have live music. It used to be an expat pub but since re-opening a couple of years ago has a very mixed crowd which is always nice.

Cafe Arts – A nice restaurant in Paquis. They do great food and good vegetarian options, just don’t ask for a Martini (you’ll get something poured out of a bottle of Martini, rather than a proper cocktail). Cosy atmosphere and lots of cultural and alternative events are publicised on the walls.

Restaurant 5 Portes – Does a great job of straddling the restaurant/bar frontier, with more of a restaurant bias. Excellent food and very delicious deserts. One of my favourite places in Paquis, just round the corner from Cafe Arts.

The Hamburger Foundation – It’s a restaurant. They don’t take reservations (so be prepared to wait in line). Great burgers and the best Martini in town.

Luigia – simply the best pizza restaurant in Geneva (even all the Italians in town agree). It’s relatively expensive, but incredibly delicious and the deserts are out of this world. Reservations obligatory unless you want take-away. I’m still indebted to Sameer and Mascha for showing me this place last year and treating me to a fantastic pizza.

Holy Cow – Sometimes it’s hard to remember that there wasn’t always a Holy Cow in Geneva. It’s a mid-low priced (for Geneva) burger restaurant, cheap and cheerful decor, student discounts and good beer made by a microbrewery in Lausanne. It’s basically one of very few places to go and eat before you go out drinking, or if you just want a low key meal outside of your house.  Sometimes it smells of burned hamburger.

How to: Forge metal

A couple of years ago now I taught myself how to do rudimentary metal forging using videos from the internet and the occasional digitised book. Here’s the summary of how to do it if anyone else wants to have a go!

Warning: Learning to forge things in metal is dangerous, you should proceed with caution at all times. In particular you risk setting fire to things (including yourself), burns, self inflicted stab wounds and other nasty things if you aren’t sensible. 

Safety items you should have to try forging: A head mounted welding face mask (you will need both hands). Flameproof overalls (I use Nomex ones, also remember to wear natural fibres underneath just in case). Leather welding gloves. Tongs for manipulating very hot things. A face mask to protect you from projecting molten metal is also a good idea. A leather apron can also be useful as it’s comparatively resistant to molten metal. A bucket of water handy is also a very wise precaution.

Step 1: Decide what you want to forge.


This weekend I decided to forge a moon pendant, based on the above sketch.

Step 2: Carve it in wax. I used a tea light from IKEA, vanilla scent, however you can also buy proper (harder) carving wax from specialists. If you want high detail, this is a must! You can also buy it in pre-formed ring blanks. Be careful when cutting the wax, I’ve previously cut myself quite badly doing this using an Xacto craft knife, but fortunately it’s healed now!

Step 3: Cast the mould. For this you should find a tin can (aluminium or steel) that’s big enough to hold the wax piece. If you’re only detailing on one side then an open mould is fine, stick something on the top of your model to allow it to be rested on top of the can. Otherwise, for more complicated castings such as rings, you should include a sprue and a cone on the top of the mould to allow you to pour in the liquid metal. To make the mould, I used pure plaster of Paris, however you can/should also add some sand to improve the strength of the mould. It’s a good idea to tap the side of the mould vigorously to ensure that any bubbles on the wax model get dislodged. Ideally you should put the mould under a vacuum to remove all air bubbles, but vacuum pumps are hard to come by. I’ve managed without one so far.

Step 4: Wait for the mould to dry. There’s no shortcut for this.

Step 5: Bake out the mould to melt the wax and ensure that the plaster/plaster+sand mixture is fully cured. You might want to build a mini kiln for this, here’s mine. 20170722_195429

It is constructed from a concrete air brick, sawn in half and then drilled to create a cavity and a connection point for a heat gun. It has a top half which is the same, but with a small vent hole instead of the inlet. Here is a picture of the completed kiln.


Note the small hole on the top for the hot air to come out of. I placed the cured mould, complete with the wax model, upside down in here for about 30 minutes to bake it and melt out all the wax. You could probably just pour in the molten metal, but baking out seems to be more reliable.

Step 6: Whilst the mould is baking, you can set up your furnace. I used an arc welder, since it’s easy to get hold of and runs on easy to handle electricity rather than anything chemical (coal, propane, etc.). To turn the arc welder into a tool for forging, you should remove both the ground clip and the welding rod holder and replace them with large metal mole grips. These can be used to hold the electrodes and/or a crucible. I would recommend using a graphite crucible and graphite rods extracted from 6V ‘lantern’ batteries – be careful not to crack them while extracting them from the 4 zinc housings within the battery. It’s also worth noting that if you obtain them this way, they will be coated in a paraffin type wax which will burn off after the first time you strike an arc.


Here is my ‘workbench’ you can see the arc welder is the yellow box at the end, with both electrodes replaced with mole grips. I used a small part of the concrete air-brick as a stand for the crucible, here’s a close up also complete with my cracked crucible which I disposed of after this casting and the mole grips holding carbon rods:


Step 7: Melt the metal. For this step I can highly recommend using some borax as a flux, you can buy it (normally) from your local chemist. It’s not the nicest of chemicals, even though it was used as washing powder in the 19th century, so use sparingly (a light dusting in the crucible is plenty I find) and handle with care. Next add your metal in small chunks that fit in the crucible. For this project I used some silver elements I had left over from another project. Silver is cheap, at least compared to Gold, and melts a lot easier than Copper. Beware of metals containing Zinc as breathing in the vapour can give you the shakes and fever like symptoms. Copper is VERY HARD to melt, and once molten, re-solidifies almost instantly. I started practising with it and was mightily relived when I switched to casting in Silver.

Step 8: Pour into the mould. You should remove the mould from the kiln and place it next to your crucible workstation before attempting this. Pouring the metal in is surprisingly difficult and you really don’t want molten metal splashing or pouring onto anything else (you, clothes, wood, anything that will melt or burn). Once you’ve melted the metal, be sure to lift your welding visor otherwise the mould will be invisible (along with anything else that isn’t an electrical arc or glowing metal).

Step 9: Apply the plunger (carefully!). If you look carefully at the photo of my workbench you’ll see a broken stick of wood attached to the lid of a jam-jar. This is my plunger for steam casting. When you have poured the metal into the mould, you can push the plunger down on top to generate steam and force the metal into unoccupied parts of the mould. You should prime the plunger by stuffing it with newspaper and then wetting it (in your safety bucket of water). However, if you are casting in an open mould, there’s limited benefit to the above, as assuming you used a sensible amount of flux, and it’s hot enough, the metal will naturally fill the mould. In this case, I was overzealous and plunged the plunger down onto my filled mould whilst the Silver was still liquid, creating the following mess:


You can see the blobs of molten silver that were pushed out by the steam, and the blackened lump in the centre is what I pulled out of the mould itself, which was also looking rather worse for wear. It’s worth noting that metals, generally, can be purified and re-cast even when they look rather messy. The impurities will either burn off or sink to the bottom of the crucible.


The mould, after use. This type of mould is only intended for a single use. However since I was in a hurry (never cast in a hurry!), I decided to re-use it and modify my original design somewhat. I placed the lumps of silver into the mould and created an arc between the two electrodes in close proximity to the mould (1-2mm max), in order to re-melt the silver into the mould. This worked very well, though changed the nature of the end product.

Step 10: Quench and finish. After re-melting, I was careful to wait for the casting to cool before dropping the whole mould in my handy nearby bucket of water. After a few seconds bubbling, I retrieved the cast using a pair of pliers and tidied it up using a grinding wheel and a wire brush polishing wheel. Since the mould had been abused during the two pours of the casting process, there were some fragments of gypsum (plaster) embedded in the surface of the final cast. These soon came out under the polishing wheel whilst I was improving the overall shape and look of the piece. 20170722_195339

Here is the front of the finished pendant, with a very lunar surface look to it. There’s a 2.4 mm hole drilled into the top for the silver chain, at a slight angle to help it sit ‘moon side up’ when worn as a necklace. I didn’t cast/make the chain, as that’s far too much like hard work, instead buying it from a local jeweller.


I polished the back side of the pendant to a much smoother finish, with the idea that it would be more comfortable to wear. During the polishing process it got so hot that two tool marks imprinted into the Silver, you can see them towards the bottom. I decided to leave them as they look rather like footprints to me!

Casting is a lot of fun, however it can be extremely hazardous so should only be done with extreme care. It took me about 3 months of occasional evening and weekend practice before I was able to make my first ‘proper’ cast, and I’m still a very, very long way from even a student level of proficiency. But it kind of works, and I’m very happy with the end result. I’m also not going to give up my day job!

P.S. I must give credit to The King of Random for his excellent Arc Furnace video which was my inspiration for using the arc welder to melt metal!

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