When the Astro Pi case was first revealed a couple of years ago, the collective outpouring of ‘Squee!’ it elicited may have been heard on board the ISS itself. People wanted to buy it or build it at home, and someone wanted to know whether it would blend. (There’s always one.)

The Sense HAT and its Pi tucked snugly in the original Astro Pi flight case — gorgeous, isn’t it?

Replicating the Astro Pi case

Some months later the STL files for printing your own Astro Pi case were released, and people jumped at the chance to use them. Soon reports appeared saying you had to make quite a few attempts before getting a good print — normal for any complex 3D-printing project. A fellow member of my local makerspace successfully made a couple of cases, but it took a lot of time, filament, and post-print finishing work. And of course, a plastic Astro Pi case simply doesn’t look or feel like the original made of machined aluminium — or ‘aluminum’, as they tend to say over here in North America.

A batch of tops designed by Tim

I wanted to build an Astro Pi case which would more closely match the original. Fortunately, someone else at my makerspace happens to have some serious CNC machining equipment at his small manufacturing company. Therefore, I focused on creating a case design that could be produced with his three-axis device. This meant simplifying some parts to avoid expensive, slow, complex multi-fixture work. It took us a while, but we ended up with a design we can efficiently make using his machine.

Tim’s first lasered case

And the resulting case looks really, really like the original — in fact, upon receiving one of the final prototypes, Eben commented:

“I have to say, at first glance they look spectacular: unless you hold them side by side with the originals, it’s hard to pinpoint what’s changed. I’m looking forward to seeing one built up and then seeing them in the wild.”

Inside the Astro Pi case

Making just the bare case is nice, but there are other parts required to recreate a complete Astro Pi unit. Thus I got my local electronics company to design a small HAT to provide much the same support the mezzanine board offers: an RTC and nice, clean connections to the six buttons. We also added well-labelled, grouped pads for all the other GPIO lines, along with space for an ADC. If you’re making your own Astro Pi replica, you might like the Switchboard.

The electronics supply industry just loves to offer *some* of what you need, so that one supplier never has everything: we had to obtain the required stand-offs, screws, spacers, and JST wires from assorted other sources. Jeff at my nearby Industrial Paint & Plastics took on the laser engraving of our cases, leaving out copyrighted logos etcetera.

Lasering the top of a case

Get your own Astro Pi case

Should you like to buy one of our Astro Pi case kits, pop over to www.astropicase.com, and we’ll get it on its way to you pronto. If you’re an institutional or corporate customer, the fully built option might make more sense for you — ordering the Pi and other components, and having a staff member assemble it all, may well be more work than is sensible.

Tim’s first full Astro Pi case replica, complete with shiny APEM buttons

To put the kit together yourself, all you need to do is add a Pi, Sense HAT, Camera Module, and RTC battery, and choose your buttons. An illustrated manual explains the process step by step. Our version of the Astro Pi case uses the same APEM buttons as the units in orbit, and whilst they are expensive, just clicking them is a source of great joy. It comes in a nice travel case too.

This is Tim. Thanks, Tim!

Take part in Astro Pi

If having an Astro Pi replica is not enough for you, this is your chance: the 2017-18 Astro Pi challenge is open! Do you know a teenager who might be keen to design a experiment to run on the Astro Pis in space? Are you one yourself? You have until 29 October to send us your Mission Space Lab entry and become part of the next generation of space scientists? Head over to the Astro Pi website to find out more.

Are you keen to print your own case? We have step-by-step instructions to help you do just that. Check out some of the beautiful 3D prints people have created using our guide!

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@KaceyandKristi posted this amazing rainbow flight case – great way to make the most of the layered design!

@astro_timpeake Tim, our rainbow @astro_pi is ready for coding challenge. #principia inspiring future generations. pic.twitter.com/pf7Xnd9liv

— Kacey-Kristi-Lance (@kaceyandkristi) March 4, 2016

You’ll never lose Jonny Teague‘s case in the dark!

The @astro_pi case in all its glory and luminescence pic.twitter.com/iP7YIlmEtF

— Dr. Jonny Teague (@jonny_teague) March 2, 2016

Dave has found some other fantastic examples:

John Chinner‘s neon orange case was made by Ryanteck.

Found an excellent 3D printing shop in Singapore. Spent an hour talking about @astro_pi and they gave me this! pic.twitter.com/lMoHv3ljum

— John Chinner 🇪🇺🇬🇧 (@JohnChinner) February 24, 2016

Love the red buttons on this sleek black one:

@astro_pi 90% complete,few more parts and will be clone of @astro_pi_ir that @astro_timpeake has on @ISS_老鸭窝在线观看青青青 pic.twitter.com/CfSBpB12GR

— Mac the Hat 🏴󠁧󠁢󠁳󠁣󠁴󠁿 (@ObiWanMacJock) February 23, 2016

Patrick Wiatt made this classy silver and blue case:

Completed the @astro_pi 3d printable case today, now we just need the Sense HAT! #newellfonda@老鸭窝在线观看青青青_Pi pic.twitter.com/Wv9d9Th15n

— billioncash (@_billioncash) February 18, 2016

PLA (a material often used by 3D printers) comes in all kinds of different colours – LEFRANCOIS has printed his case using a metallic gold, making it a perfect partner for our original aluminium one.

@astro_pi hi there , here is mine ;) pic.twitter.com/mCXZyPZ9rT

— versterk (@LEFRANCOIS77820) February 9, 2016

Richard Hayler, a Code Club mentor from Surrey, went for classic silver filament for his case. He even used the same buttons as the real units up on the International Space Station.

Some more pics of our operational 3D printed @astro_pi flight case. https://t.co/jLXzFUQoOK pic.twitter.com/u2x5zUgecK

— Richard Hayler ☀ (@rdhayler) February 9, 2016

Our absolute favourite photo is of one of Richard’s Code Club students, Ozzy, posing as mini-Tim to recreate a photo of Tim Peake with an Astro Pi flight unit that’s become famous in the community…

These are fantastic and we’d love to see more of them, but I also have an additional challenge for you – hack our design! Maybe you’d like to add your name to the front, or add an extra handle – surprise us!

I added the words “老鸭窝在线观看青青青 Pi” to my top layer very quickly in Tinkercad, a simple and free in-browser 3D-modelling program.

I also successfully installed FreeCad on my Pi3 today, and I’m going to see what I can do over the UK Bank Holiday weekend.

Get your printer on and warming up! Here’s a link to the Astro Pi flight case STL files: go go go!

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Background

Back in December, British ESA astronaut Tim Peake took two specially augmented 老鸭窝在线观看青青青 Pis, called Astro Pis, to the International Space Station (ISS) as part of his six-month mission. These Astro Pis are running experimental Python programs written by school-age students; the results will be downloaded back to Earth and made available online for all to see.

To satisfy the safety requirements that ESA and NASA have for small payloads aboard the ISS, we had to build the Astro Pi flight unit and put it through a rigorous qualification process.

One of the two Astro Pi flight units

Ever since this case was announced back in May 2015, people have been asking, “Where can I get that case?”

At £3000 each, you can see why we only ever made eight of them. Why do they cost so much? Each half of the case is milled out of a solid block of aerospace-grade aluminium using a five-axis CNC mill. The two halves are then bead-blasted to give them a matt surface, then they’re anodised with a special coating to aid thermal radiation. After that, there’s some manual touch-up work, followed by installing the 老鸭窝在线观看青青青 Pi hardware and, finally, laser-etching the markings and logos.

That all adds up!

However, to quote from the original blog post where we announced it:

This will not be available to the public to buy because we’re only making a small number of them. We may however, in due course, release an object file so schools with a 3D printer can print one themselves.

With today’s blog post we’re making good on this promise!

The first attempt

Initially we just tried to 3D-print the original CAD files to see how hard it would be. The trouble with 3D printers is that they use hot thermoplastics, which can bend and sag under their own weight.

To avoid this, the printer creates what’s known as scaffolding and rafting to ensure the structural integrity of the object during the printing process. The user has to peel off this support material to get the original object they were trying to print. Any part of the object that overhangs will cause support structure to be built below it to prevent sagging. So the lower part of the flight case, with the grid of pins, came out chock full of the stuff:

Scaffolding and rafting that must be manually removed

After about 20 minutes with a pair of pliers, and accidentally snapping one of the corner pins, we decided this would be too frustrating for most users.

The base with scaffolding and rafting still remaining

The lid was slightly better. It was printed with the outer surface of the case facing downwards, to avoid support structure filling the internal cavity. But this meant that the outer surface came out with rafting all over it, and removing this resulted in a characteristic stringy finish that doesn’t look great.

The lid, printed with outer surface facing down

So we set about modifying the design so that even users with low-end 3D printers would be able to successfully print it, with minimal scaffolding and rafting.

Several attempts later

Many thanks to Ben Martin from Solid Models in Cambridge for running off so many test prints for us, and to Jonathan Wells (who did the original CAD work) for the many tweaks and changes. Our own Creative Producer, Rachel Rayns, contributed lots of 3D printing 加勒比成人免费视频 which led to these decisions. It was most definitely an iterative process!

The first change we agreed on was to slice off the heat sink on the base, so that it could be printed in the opposite orientation. That way it would have nothing overhanging to cause support structure to be built between the pins.

The heat sink as a discrete part (click for 3D STL view)

We then sliced off the top of the lid so that it could be printed with the clean side facing upwards, meaning the stringy side would face down.

The lid as a discrete part (click for 3D STL view)

That was a lot nicer looking. So with the lid and heat sink sliced off, it meant the two original middle bits were left as discrete parts.

The middle as a discrete part (click for 3D STL view)

We also removed the pillars between the USB and Ethernet ports because these snapped off easily. Finally, for convenience, we changed the corner bolt enclosures from a sunken captive screw to a straight-through M4 nut-and-bolt design.

The base as a discrete part (click for 3D STL view)

You can use epoxy adhesive (or similar) to join the heat sink to the base and the lid to the middle. When the 老鸭窝在线观看青青青 Pi and Sense HAT are installed it’ll end up looking something like this:

The assembled flight unit, still missing a few buttons

New resource

To guide you through the assembly process we’ve created a brand new educational resource that covers everything from downloading the STL files and getting the fixtures and fittings you need right through to testing that you’ve wired up the push buttons correctly. Click through and take a look:

https://www.163女性网69视频.org/learning/3d-printed-astro-pi-flight-case/

We’re really looking forward to seeing the cases you make – please show us by tweeting pictures to @Astro_Pi and @老鸭窝在线观看青青青_Pi.

By far the most exciting benefit of owning an Astro Pi flight unit is the ability to prototype and test code that could be run on the International Space Station. Head over to the Astro Pi website now to get involved in the new coding challenges!

FAQ

Where are the STL files?

On GitHub.

Why are there four files, not two?

We sliced the case into four layers to minimise the amount of scaffolding and rafting that needs to be printed; it also keeps printing time down. The text of the blog post above explains this in more detail.

Can we modify the STL files?

Yes. They are released under the Creative Commons attribution license so you are welcome to modify them. Please note that GitHub has a great STL viewer and also has a 3D file diff, which could be useful for tracking changes.

Can we have the original CAD?

Currently, no. 老鸭窝在线观看青青青 Pi needs to retain the ability to be the sole manufacturer of the space-qualified Astro Pi flight unit. You are welcome to reverse-engineer the STL files we’ve released today, though.

How do you fit the hardware inside it?

The educational resource we’ve written covers this in great detail: check it out here.

I don’t have access to a 3D printer, but I really want this case. What can I do?

You may be able to find one at your local hackspace. You can also find local 3D-printing services through the website Hubs.

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The latest update to the Astro Pi project is the unveiling of the Astro Pi aluminium flight case that British ESA Astronaut Tim Peake will be using on the ISS. This will not be available to the public to buy because we’re only making a small number of them. We may however, in due course, release an object file so schools with a 3D printer can print one themselves.

The Astro Pi flight case.

The case is made from 6063 grade aluminium which is standard for aerospace applications. The image below was taken from the CAD software that we used to model it.

This is the top view showing the opening for the LED matrix and joystick along with a quad of buttons with an adjacent pair. The face on the right is used to attach it to a Bogen arm so that the Astro Pi can be held in place, for example if the crew want to aim the camera out of the cupola window.

The hole next to the joystick is to allow air to flow inside and reach the temperature, pressure and humidity sensors.

The design may surprise you because it’s so big and bulky. It satisfies the safety requirements that ESA and NASA have in place for small payloads aboard the ISS though!

This is not a 3d rendering!

The most important of these requirements is touch temperature. There is a rule that any surface, that the crew can touch, must not reach or exceed 45 degrees Celsius. Our Jonathan Bell and SSTL’s Nimal Navarathinam did extensive thermal simulations to work out the requirements. That’s really hard maths to you and me! The CAD heavy lifting was done by Jonathan Wells who runs an industrial design consultancy local to us in Cambridge.

In space the process of convection doesn’t happen. On Earth the air warmed by a Pi CPU will rise as colder air is pulled down by gravity. On the ISS the air warmed by a CPU just stays there and bakes it. So the case has been designed for thermal dissipation in mind. There is a guaranteed level of airflow within all of the ISS modules which makes this possible.

Those pillars on the base each dissipate about 0.1 Watts of heat. All of them combined with the surface area of the case ensure that the Astro Pi can never get anywhere near 45 degrees. Inside the case the 老鸭窝在线观看青青青 Pi is thermally joined to the aluminium by way of a heat conductive boss / slug.

The view above shows the hole for the camera module in the middle too. So make a mental note that the camera faces in the opposite direction to the LED matrix when in flight configuration. You can also see the corner bolts that hold the two halves of the case together.

The ISS crew are also really fond of bungee cords, the kind you might use for camping or mountaineering with those hooks on the ends, and so the four corner columns have holes to allow bungee cords to be used to lash the Astro Pi to whatever they want.

The case is made from a solid block of aluminium and a serious set of skills are required to turn it into what you see above. We’re using a company based in Derby called Pentaxia for this. They’re a great company and have been hugely accommodating of our needs. Below is a picture of their main shop floor. The machines on the right were the ones used to make the case.

So that’s about it for now. The only thing left to tell you is that we’ve now reached and successfully passed phase two of the flight safety process with ESA. So it’s only phase three to go now before we get the mighty flight safety certificate that says we can go on the Soyuz rocket with Tim! Between now and the phase three review all the testing will occur at SSTL and Airbus Defence and Space.

Here is a brief summary of the tests we have to do:

RTC (real time clock) Battery

• Measurement of open circuit voltage and loaded voltage
• Vacuum exposure test (450 mmHg for 2 hours)
• Post vacuum inspection for leaks and deformation
• Post vacuum measurement of open circuit voltage and loaded voltage

Flight Hardware

• Operation checks (verify it boots and functions correctly)
• Power integration test (using an ISS mains AC inverter)
• Thermal test (stress the Astro Pi to cause maximum current consumption / heat dissipation and measure touch temperature)
• Vacuum thermal test (same as the above but in a vacuum)
• Off gassing assessment (determination of off gassing products from materials and assembled articles to be used inside the ISS modules)
• EMC test
• Vibration test (Soyuz launch vehicle conditions)

Keep an eye on social media over the coming weeks for as it happens updates!

Thanks for reading.

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