Tesla testing

Friday 27th March 2015

Last week I went up to Bristol to test drive the Tesla Model S electric car. I've never loved driving a car as much as this.

In fact the Model S is more like an electric supercar. It's becoming well known partly because the top of the range model features a brilliantly-named Insane Mode which accelerates the car like it's on a drag strip.

First the good points, and there are lot of them.

Good points

The car is beautifully smooth to drive; responsive and solid with adjustable suspension and steering. It's enormous fun and feels a lot lighter than its 2,200kg. The acceleration is just unbelievable, everyone told me that electric cars go fast, but 0-60 in four seconds takes your breath away.

Driving the car really feels like you're in the future - essentially it's a beautifully-designed computer on wheels. It's got adaptive cruise control that keeps you a set distance away from the car in front. In cruise mode when you indicate right, the car accelerates automatically to help you overtake. The autopilot mode, coming soon and which will be installed automatically over the internet, pretty much drives itself on a motorway. After this, getting in a normal car feels like a pony and trap.

There's loads of space, including under the bonnet (or 'frunk' as they call it) because the electric motors are between the wheels and the batteries sit under the chassis.

The range is pretty good with 200-300 miles on a full charge with a network of charging points around the country. Tesla supercharger stations fill the batteries in half an hour, and you can charge it overnight at home too.

Bad points

Although the driver who took us out claimed that there was nothing he didn't love about the car, there are a number a bad points.

First, and slightly worryingly, the software in the central console seemed a bit buggy. A couple of times it froze for a few seconds, the music skipped and it was occasionally slow to respond or unresponsive. They're constantly releasing software updates for it, and I know there are always teething problems with new code, so I'm happy to let this slide.

My biggest criticism is that it feels very American - flashy and attention seeking. For example the key fob looks like a tiny Tesla (see pic), which isn't something I'd expect from a European car. The control screen is unnecessarily large and dominates the front of the vehicle. I'd like to see a toned down version for normal people.

Lastly it's very expensive - the one we drove was £80,000. Check out the design studio to configure yours - my preferred options were £100K and change.

Would I buy one?

I really want our next car to be electric, but to be honest it's not going to be a Model S. For a start, I don't want to spend that much on a car, but I'd like something less brash. I'm hoping to test drive a BMW i3 soon, so I'll keep you posted!

To end, I want to share a thought. At the end of my drive I had a moment of realisation: This is the most high tech car I've ever seen, but one day the Tesla Model S is going to feel old-fashioned.

I can't wait to see what high tech looks like then. 


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Making a knife

Friday 20th March 2015

I don't think I've ever learned so much in one day. A friend and I went on a knife-making course with Dave Budd in Devon, where we started with a steel bar and ended up with a rather fetching blade.

I couldn't recommend Dave highly enough, he is extremely patient, friendly and knowledgeable. 

I've never tried metalwork before, the tricky bit seems to be getting the temperature right. Dave gave us tips on what colour the steel should be for different parts of the process: we need a bright orange for this step, or a dull red for that one. Once the metal is the right colour, it's like working clay, the steel bends easily and is great fun to work with.

Here's a quick rundown, each step has an image below it.

Edit: Dave sent me a bunch of corrections!

Bashing it into shape

  1. We started with a half inch bar of spring steel

  2. First of all we heated and hammered one end flat until it was about 5mm thick, and then hammered a point onto one end.

  3. When you start flattening the sharp side of the blade, the steel will try to bend away from the sharp side. To counter this, we curved it - the sharp side is going to be the inside of the curve.

  4. We flattened the sharp side, the blade has straightened itself out during this process.

Refining the blade

  1. We hammered the other end of the bar into a point to make the tang (the bit that goes inside the handle)

  2. Next we refined the blade to about 1mm on the sharp side, and then gently straightened it out. The blade is covered in a layer of scale (iron oxide, rust) which I've accidentally hammered into the surface of the blade, but hey - it's hand made.
  3. Then we ground the blade down to the shape we wanted. This is the point where it suddenly turned from a lump of metal into a knife.

  4. Then it was time to harden the metal. This is done in three stages: Normalising (letting it cool from a red glow) to soften the metal, refine the grain size and de-stress the steel; Hardening (quenching the metal in oil from a red glow) to harden it, but leaves the steel brittle; and finally Tempering (in an oven) to reduce the hardness and brittleness.

Finishing touches

  1. Next we ground the scale off the blade (you can see pits where I hammered the scale in) and sharpened it. It's really, really sharp.

  2. The final step of the course was to fit a handle. We drilled some little pilot holes into a lump of cherry wood, then heated the tang and burned it into the handle. Awesome.

  3. When I got home, I worked the handle into the shape I wanted with sandpaper, starting with a rough 80 grit and working up to superfine 1000.

  4. Finally I bought some leather from eBay (I love eBay) and made a sheath for it. Awesome!


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Walking a thousand miles

Friday 13th March 2015

A while back we built two websites for Cornwall NHS - one to help people track calories and one to track the distance that they walked. I learned that I should be eating no more than 1,800 calories a day, and walking at least 10,000 steps per day (about 4.5 miles).

This was news to me so, serial hobbyist that I am, I obsessively measured data about myself. I got the awesome MyFitnessPal app and tracked my weight, food intake and exercise.


Last summer I decided to see how quickly I could walk 1,000 miles. Before I started on July 7th, I came up with two predictions:

  1. I'd be finished by Xmas - so it would take less than six months
  2. On weekdays where I walk the dog, I walk twice as far as when it's not my turn

So I tracked my steps every day and fed them into the programme that came with my pedometer.


I started well, but I was surprised how much more I walk in the summer compared to the winter. My maximum was 15.2 miles walking the South West Coast Path in early November, and Christmas day was my worst day, walking just 1.6 miles (and probably eating the most calories too).


It turns out I don't walk as much as I thought:

  1. It took six and a half months in total (199 days), I averaged just over 5 miles a day
  2. On dog walking weekdays I walk 1.6 times further (5.6 vs 3.4 miles)

The other statistic that came out of the pedometer programme was that I burned over half a stone (4.1kg) of fat while I walked!

Anyone want to borrow a pedometer?


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Making Charcoal

Friday 6th March 2015

One of my most ambitious projects is to make a bronze sword, which involves learning a whole bunch of new skills. My original plan was to get tin and copper ores, and smelt them to refine the metals, but after a visit to Geevor tin mine I realised that I'll need at least a tonne of rock, so I'm going to buy tin and copper metal and start from there.

So my first task is to make charcoal to make the bronze.

What's charcoal?

I didn't really understand what charcoal was until I started researching this project. Essentially it's wood that's been heated in the absence of air, to remove all the water, oils and other volatile chemicals, and leaves pretty much just carbon. The absence of air is the really important thing here, because otherwise it just burns.

Because all the water and stuff has been removed, it burns massively hotter than wood, hot enough to melt tin and copper and make bronze. I only need a small amount to make a sword, so I found a method that you can do in an afternoon, and Rob and I got stuck in.

Here's what we did, and you've got to guess what we did wrong.

A simple kiln

First we acquired a 200 litre drum and a 60 litre drum and cut the tops off with a jigsaw (below, left), which is a legitimate use for that tool. We cut small flaps into the bigger drum to allow air to get in.

Both drums had previously contained engine oil that we didn't want in the final charcoal, so we lit fires in them both.

While they were cooling down, Rob sawed up some dry logs (below, middle) and we packed them into the smaller drum so tightly that we could turn it upside down without them falling out (below, right). This is important.

So far so good.

Cooking the wood

Next we turned the small drum upside down and placed it in the middle of the big drum. Then we packed sawn up pallets all around the edge of the big drum (below, left) and set light to it. We kept feeding the fire and let it burn for two hours (below, middle).

This heats the wood in the smaller barrel in the absence of air, which turns it from wood into charcoal. After two hours we let the fire die out, and let the barrels cool down until we could touch them (below, right).

Then we tipped the large barrel onto its side and carefully pulled out the small barrel, which was now full of charcoal!

The charcoal was still really hot, so we put a lid over the barrel and left it for a few hours to cool down.

Cocking it up

Spotted the mistake yet?

When we came back to check on it three hours later, the charcoal was on fire!

Because we were so excited we removed the small barrel too early and a stray ember from the fire must have landed amongst the charcoal, which was nice and hot and suddenly had access to lots of oxygen.

Oops. But it was obviously good charcoal because it was blisteringly hot.

So we've all learned an important lesson today here folks: you can't hurry love. We'll be making another batch soon, and we'll be much more careful this time. And we salvaged one bag of usable charcoal before it all burned.


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