engineer

tim   .

                                                      


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.   hunkin

                                                         


cartoonist

 

THE MAKING OF PIRATE PRACTICE  

Pirate Practice is a mix of two completely separate ideas – bouncing and piracy. My interest in bouncing comes from the Namco horserace game ‘Final Furlong’. I once saw four men in pinstripe suits furiously bouncing on plastic horses – an unforgettable sight. There’s something ridiculous about bouncing which makes both people doing it and people watching it laugh, so it’s a good starting point.

 

A few years ago Southwold pier opened a kids shop called ‘Mermaids and Pirates’, full of traditional pirate stuff (skull and crossbones, cutlasses, model pirate sailing ships, etc). At the same time the Somali pirates appeared in the news and I thought the pier needed to add some modern pirates. I don’t really understand why traditional pirates are respectable but modern ones are pariahs.

 I might never have embarked on the machine but I had got frustrated trying to make an environmental simulator ride in a bird hide because I had got bored of the climate change debate. I needed to change direction and with my grandchildren coming to stay in a week I decided to make a prototype bouncing mechanism. They enjoyed it, which was enough for me to embark on a properly engineered version.

     

At that point I hadn’t committed myself to pirates, but it did start me researching the Somali pirates online and I quickly got hooked. The first Somali pirates were fishermen desperate because there weren’t any fish. Without effective government, foreign boats had been hoovering fish from their territorial waters and dumping illegal toxic waste. Piracy was the perfect ‘direct action’, taking money from the richest people on the planet (the ship owners) and getting it to the poorest. Wikipedia estimates that the Somalis lost about twice as much through illegal fishing and dumping as they ever recouped via piracy a year. However, after the fishermen pirates’ initial success, I think the business got taken over by African warlords so the ethics are now murky.

       

Since their peak in 2009, the pirates have been less successful because of armed patrols and mercenary soldiers onboard ships, so the story probably won’t last. However, anger at the super rich, the CEOs and bankers with vast salaries, is here to stay. While I was making it there were lots of news stories about how little tax rich people pay. I nievely hoped my machine might help to make rich people feel embarrassed, but to make it work visually, my super rich icon had to be a fat oligarch, with girls and a super yacht. The problem is that most of the super rich are so boring and faceless they would not identify with my oligarch. Still, I hope it will be therapeutic for everyone else to vent their frustration.

 

   

 

 Technical Details

first prototype video

 My rough prototype showed me how not to make the final version. It was very noisy (particularly the loose fitting guides for the seats), the springs weren’t strong enough (there wasn’t enough space) and the frame was unlikely to scale up to carry a heavy adult.  So mark two has a pivot instead of linear motion. This was a simple (large) bearing at the back, leaving lots of space for the springs along the bottom. I spent many hours looking at spring tables and doing spring calculations. I’d never realised that a spring with a large outer diameter can be stretched much further – to over twice its unstretched length. Using stock springs (custom ones are really expensive) the final arrangement can’t quite balance a heavy person, so they will have use a bit more energy bouncing. While I was working on this, I had a rare Eureka moment, realising that the springs could weigh people, so the bouncing would be as effortless as possible for everyone. I fitted linear actuators which gradually stretch the springs when you first sit on. When the spring tension balances your weight, the seat starts to rise. This is detected by a sensor, which turns off the actuator. There was another advantage – the seats aren’t attractively bouncy when the machine isn’t in use, so kids won’t spend all day bouncing on them.

 

second prototype video 

Making all this only took a couple of weeks. Incorporating the chain and pulleys from an old stair lift I’d been given 7 years ago was particularly satisfying. I wasn’t busy at the time so I decided to add a sideways movement so the pirate ‘boats’ could be steered to avoid obstacles. I stumbled on a nice rocking motion pulling a little boat along a wave shaped acrylic bar. I then wanted some sort of motion for the sea. Unlike the bouncing, spring mechanism, the boats and sea were obstinately problematic and plagued the whole project. I spent over two months on them. The final sea is mark 5 and I was still making new boat carriages the day before the machine finally went to the arcade.

 

final bouncing mechanism video

boats video

After lots of tests and prototypes, I decided to make the sea out of stainless steel welding wire, bent in wave shapes, moving from side to side. I ended up with a complicated mechanism that quivered and juddered and certainly didn’t resemble the motion of the sea. The boats got complicated because I decided they had to be front lit, and needed to have LEDs moving with them. So I had to get electricity to the boats. I replaced the Perspex with two stainless wavy rods, one positive and one negative. At first this seemed to work OK, but the lights sometimes flickered and the boats occasionally jammed. I kept fiddling with it but felt I never quite got to the bottom of the problem.

 

sea video 

After a break for 6 weeks working in the US, I returned to look at it afresh. The sea effect was awful so I started again from scratch with a circular motion and thicker wires to reduce the judder. There was now some urgency – it was only two and a half months before the summer season when I needed it on the pier. So I started working on it full time and tried to ignore distractions. It was good to have a deadline to force myself to make decisions quickly, so generally progress was fast.

   

However, I got stuck for a week trying dispense the billion dollar banknote. I thought I could suck the top sheet off a pile of paper (I’m sure I’ve seen suckers on printing machines) but paper is porous so it sucked over twenty sheets up at a time. Rex told me that he had been short changed by the cash machine outside his bank. When he complained they said ‘oh, it’s always happening’. Moving paper around is never easy. When I was researching my ‘Secret Life of the Photocopier’ film a Xerox engineer told me that the company had spent much more trying to get the paper to pass through the machine than they had on the actual electrostatic printing process. So I bought a Xerox ‘pickup and feed roller assembly’ on ebay and this just about works.

 

I still had no idea what the machine should look like. I’d thought of sticking photos of Somali pirates on the little boats but photos didn’t work for the Oligarch or the obstacles. I’d had the idea that the animation would be simple silhouettes of the characters, and deciding that everything should be silhouettes helped to pull everything together, though I still wasn’t sure about the colours – I’m never sure about colours. I made the silhouette pirates on the boats by etching thin brass with Ferric Chloride, using Press-n-Peel – it’s a technique that produces really fine outlines. The tiny fences and screens on architectural and railway models are made like this – much more delicate than laser cutting.     

 

Making the super yacht and opening mechanism went well, even though there was so little space for it. I buy my chains and spockets from a great company called Transdev who mainly sell stuff for industrial conveyors. I discovered they sell the most brilliant friction clutch, which was vital so fingers can’t get trapped when the yacht closes. The clutch has a huge range of torque, fits in a tiny space and cost less than £20.   

Six weeks before the deadline I saw a nice Arduino LED display at the Derby Makers faire and thought it would make a perfect timer, so people could see how long they’d taken to storm the Super Yacht. Adapting it wasn’t totally straightforward though. It took me ages to discover that the LOL shield board (Lots Of Leds) was incompatable with my Decemillia Arduinos, so I had to buy two new Uno Arduinos. Then I always find the Processing programming language awkward, even though I can get basic things to work. Kindly Matt Little, who had the display at Derby, wrote the code for me. Finally one of the new Arduinos refused to talk to the computer (another software bug) so I had to buy yet another one. I’m so thankful I’ve stuck to using PLCs for the main machine logic, because they are so completely stable. 

With just over two weeks to go, I still hadn’t done anything about the animation of the pirates storming the yacht, except to book my friend Gary Alexander to come and collaborate on it. In a couple of days we had a plot, got HD video from the media player playing on the monitor, and worked out a system using photoshop and after effects to produce it all. I was so excited the first time I saw my little characters running around inside the yacht. It really didn’t feel like watching a screen.  

The sound got left till last – as always. The home videos the Somali pirates make on their captive ships often have Somali pop music because they broadcast it over the ships Tannoy system…and its really good music, though surprisingly difficult to find. 

Electrically, the machine was jinxed. In a period of just over a week I had eight consumer electrical items die on me – An external hard drive, an SD card reader, a USB to serial adaptor, an Arduino microcontroller, a heat gun, a CF card, a 12v switched mode psu and a thermostatically controlled solder station. A few days before I finally installed it the electrics seemed to take on a life of their own until I eventually found the problem was the battery in my Fluke meter – it really needs a low battery warning. If you have problems like this most people just think you’re a useless engineer – I have great sympathy for anyone who repairs stuff because sometimes you’re bound to be unlucky and people don’t understand enough to know its not your fault.

 

On the pier the very first kids to use it were so enthusiastic that one of the boats bounced right off its rail and jammed everything up. Adding diagonal braces made the wavy rail frames much less springy and then the machine worked. The electrical jinx continued when an actuator jammed and melted a transformer, setting off the arcade smoke alarm. Though embarrassing at the time, its good to have a near miss occasionally. I not only added extra fuses and contactors to the pirates but also checked all the other machines for similar weaknesses. Electrical faults that cause fires are much more common than those that cause electrocution.

As the machine became more reliable I started to enjoy watching people use it. People love the bouncing. I'd never really taken the game aspect seriously - the right side is much easier than the left, but a mark 2, changing the obstacle  positions and the speed of the boats and the bouncing, could be really addictive.  Not everyone realises they are Somali pirates, but this doesn't really matter. Finally I had time to draw the billion dollar ransome note. This took ages, but watching people proudly clutching their 'cash' made it well worthwhile.

   

 

 



 

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