Wednesday, 17 September 2014

Clock number 1

Now that I have moved into my man-cave, I am able to start working on a number of projects that have been on hold whilst we rebuilt the house. Stuff like rebuilding a computer, sorting out the XBMC media box, and stuff like that. And building cool things out of Lego.

One of the projects that has been ticking over at the back of my mind is to build a clock. A quick internet search shows lots of ideas of building clock faces out of Lego, and some of these are very artistic. A lot of work goes into making some of these designs, and eventually my clock will have an arty face as well.

For the idea in hand, I am not content to use a purchased clock mechanism. The challenge is to build the mechanism as well. For this, Lego Technic is my weapon of choice, but there are a number of challenges:

  • Lego axles are cross-shaped rather than round, and the gears have a cross-shaped hole in the middle so that the gears do not spin on the axle. The challenge is that a clock has two concentric axles for the hour and minute hand - three if you want a second-hand as well. So somewhere in the mechanism, at least one gear must be able to spin freely on the axle.
  • It is considered extremely bad form among Adult Fans of Lego to deliberately damage one's Lego. Therefore the drilling-out of the axle-cross in a gear is not permitted. Having said that, I confess to doing exactly that a number of years ago. 
  • The minute hand rotates sixty times faster than the hour hand. A gear ratio of 60:1 is required between the two concentric axles. Lego gears are available with 8, 16, 24, and 40 teeth (there are a few others too). I leave the maths as an exercise for the reader.
Over the course of an hour in my cave the other evening, with paper, pen, and the calculator on my phone (which is also a form of cheating), I worked out the gear ratios. I know I can look it up online, but that's not so satisfying. Then I ran into another problem: how to make sure that the start and the end of the gearing end up on the same axle. I built and rebuilt the mechanism half a dozen times before I worked that out. Some problems can only be solved by trial and error. And the solution turned out to be quite elegant. The mechanism is seen here.

On the front (in the lower part of the picture to the left) is a dark grey part , known as a "differential ". This part is found in many of the Technic vehicle sets, and your car has one too. I use it here, because it has round axle-holes. The dark grey bit itself is driven by the small 8-tooth gear to its right. The axle through the middle is driven from the back of the mechanism (top of the picture).

So here I present, with a simple face to support the whole thing, version 1 of my Lego clock. There is no drive system yet - you have to turn the minute hand manually. But the hour hand rotates at exactly the right speed when you do so. My son called it a Saturday alarm clock - you can set it for exactly the time you want, and it will make absolutely no sound at that time on a Saturday, thus allowing you to have a lie-in. so practical.

If I have nothing else to do on Saturday after my lie-in, I might start work on the drive mechanism. Episode 2 of this saga will follow in a few months' time. If you can't wait for me to build mine, have a look at what others have done.

Thursday, 11 September 2014


This week I am in Aberdeen on business. It's a fascinating place: the adverts at the airport (for pipeline inspection equipment and offshore safety training, rather than shampoo and jewelry) leave you in no doubt that this is Oil City.  There is money here: plenty of new cars on the clean streets, attractive shopping malls (which reminded me of malls in Dubai, Malaysia and London) and granite bridges between granite buildings. When you see bridges from one building to another, that's a sure sign of money.

My hotel overlooks the docks. Numerous buildings are marked with the logo of the Shore Porters Society - the world's oldest transport company - advertising its presence here since 1498. The ferry to Orkney and Shetland with its Viking logo is just over the water, and there is a truck on the docks lining up cattle wagons ready to be loaded on board. Elsewhere , the supply vessels from the offshore platforms are here to load up - giant sea trucks that carry everything except people out to the rigs in the North Sea. A constantly changing steel landscape, chugging with diesel engines night and day, bright colours clashing with the grey of the Granite City. Thank Ibis for double glazing.

This is an interesting week to be in Scotland. In a few days' time, the nation will vote about separating from the Union of the United Kingdom.  Anyone who is resident in Scotland can vote. 12% of the population of Scotland are not Scottish, which means half a million people from around the world can vote on the future of a country they know little about, yet 750,000 Scots living in England have no say, and nor do soldiers on tour of duty, nor millions of others worldwide with Scottish blood. I'm not allowed to vote. But my brother, who is of English descent (and was born in Switzerland), can vote because he lives in Edinburgh. I don't understand how that's appropriate for independence.

I also don't understand why so many people are pro-independence . I understand the laudable ideal of independence, but it must be tempered with practicality. Nobody knows what currency will be used, what language they will use ("English" being taught in Scottish schools?),  whether Scotland will be permitted entry into the EU (and how long it will take), whether the border with England will be open or policed. That uncertainty is making the international finance markets uneasy - already, billions of pounds sterling  has been moved out of Scotland, and the London stock market has slumped because of the uncertainty. Even six months ago, the papers were talking about the financial prospects of independence.

I guess it's easy for me - I'm not Scottish, so I don't understand what Scots feel about being part of the Union. Catalonia, the Flemish, Orcadiansand other people-groups around the world probably have a much better idea of what independence means. They must be watching Scotland like hawks for a precedent that will allow them to pursue their own independence.  If they do, then the break-up of the EU may well follow - ironic really, because the Independence campaign seems to rely on Scotland rapidly being integrated into the EU to survive. I can't help thinking that the Scottish First Minister has shot himself, and the country he loves, in the foot.