What I learned at BBC Broadcast Centre today…

…was that you should never, ever joke about a live demo going perfectly, because you’re using open-source hardware and software, right, so what can possibly go wrong?


This was an informal talk to an audience at the Beeb’s internal Knowledge Exchange, by kind arrangement with Jamie Knight and Sam Starling of Future Media & Technology.  There were nods of recognition when I name-dropped my recent meeting with Maggie Philbin of the BBC’s Tomorrow’s World and Bang Goes the Theory fame, through her excellent work with Teentech, and talked about the perils of live demo’s, before cheerfully launching into a demonstration of the end to end process of 3D printing,

We googled Thingiverse, took a look at the jaw-droppingly creative thing:113117 (TARDIS Transformer toy complete with bow tie!) which pleased many of the BBC technologists present, and selected a lego brick separator by common consent.  This I then imported into Slic3r, which made short work of the job, and into Printrun (Pronterface).  I hit print, and it began nicely, sticking to the bed first time as usual thanks to a heated bed and Faberdashery PLA.  On a roll.


I switched the big screen display from following my navigation of the software tool-chain on one laptop, to another laptop which was showing my ‘nozzle-cam’ X-axis enhancement, which gets the audience closer to the action, blowing the J-head of my RepRap up to full screen on a 50-inch TV.  They liked it!

I took some excellent questions; I was asked if I’d printed a gun, and I pointed out that I’ve owned a drill press for a decade and the instructions to make a ‘lower receiver’ with one have been around since the dawn of the internet, but only 3D printers can print you new body parts to replace the ones blown off with the resulting gun…  We talked about unusual applications for 3D printing, where privacy and the personal touch are all-important.  A few people recognised the logo on my T-shirt which was a good launch point to talk about the parallels between where the 3D printing industry is now compared to the advent of personal, desktop computing in the early 80’s.

At this point, thanks to Nozzle-cam on the very large screens behind me, an audience member politely asked if there should be plastic coming out of the extruder.  #epicfail

I’m a project manager, and had gone through a mental check-list in a short set-up time between a very pleasant lunch in the café downstairs and the start of the session, everything was plugged in, warmed up and ready to go.  All, except the filament!  I had cut the ivory stuff we were using to print the bust of Alan Turing at Mini Maker Faire Elephant & Castle, and reverted to the white I had spooled on the printer, but I hadn’t actually loaded it.  D’oh!


Ironically, and helpfully to my credibility at this point, I had previously mentioned to the group that the Mendel is a fairly stupid robot, and knows very little about its environment – the temperature of the hot end and the heated bed, and when it has hit the end-stops telling it home has been reached.  I described an enhancement I have planned to measure when it has run out of filament.  This has now jumped to the top of my priority list for usability enhancements to design.

The next problem came when I tried to re-load in front of a live audience – the Wade extruder I am using has an air gap between the pinch roller bearing and the hobbed bolt, and the 3mm hole leading to the hot end.  Filament is usually curved, and the cut end can be de-formed.  It’s tricky to thread it back in.  I successfully did this, while managing to maintain a thread of discussion with Jamie as a plant in the audience, however I didn’t extrude enough of the new filament through to prevent retraction from pulling it right back out again, and we had the same issue again. This is number 2 on my list of things to fix.

My next upgrade will be multiple extruders to take advantage of different filament properties (Another post on this soon), this will use a Bowden tube arrangement and now I will definitely make a custom extruder block, prioritising accessibility and easy filament feeding for on-the-fly filament changes – so both of these issues will be mitigated against before my next speaking engagement.

Thankfully, the session was fun and productive despite this issue stopping me from actually printing a completed object within time. I was assured by my hosts that it had been successful, sometimes seeing something go wrong can improve understanding of how it works, I kept up a description of what was happening and they are a smart bunch of people, they got it.  I’m told there may be an opportunity to hold a further workshop at the BBC, which I’d be delighted to do – armed with an updated checklist and an even more battle-ready Mendel!

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