It Was This Big

How big is a spanner?  They all have some markings on them, but it's not always the gap between the jaws. For AF spanners the number written on the spanner is the gap between the jaws in inches (ignoring a little clearance so that it will actually fit over the bolt). For Metric spanners it's the same, but in millimetres. For Whitworth spanners the number is the size in inches of a hole, through which the shank of a well designed bolt would fit, and the head of that bolt would fit between the jaws. For BA spanners it's an arbitrary, usually even number that gets bigger as the spanners get smaller.

That's all well and good, but what does a measurement of length really mean? You've got a ruler, but you just assume that it's got the same measurements on it as all other rulers, how can that possibly be organised? Where did the first ruler come from? The factory that made your ruler had their tools calibrated in a laboratory. That laboratory had their tools calibrated by the National Physical Laboratory (or your country's equivalent) and the NPL compares their reference length against two scratches on a bit of copper stored very carefully in Paris. We've all just sort of quietly agreed that those two scratches are a good distance apart. When it comes right down to it, describing the size of something is just comparing its size to something else.

I had to buy a socket in the wildly inconvenient size of 1 and 5/16 of an inch (AF), while it does have this number on the socket itself, the packaging has a far less useful (although somehow more honest) description of the size. It says "Classic size for Hub Nuts on Mini, MGB and Triumph TR4". It's not a measuring convention that I want to start using in my tool box.

Richard "0.01959 Smoot" B

If the Cap Leaks

Car maintenance meets automotive history. The cap on the brake fluid reservoir on my sports car is leaking a little bit so I wanted to replace it. Caterham don't have them in stock, and they're overpriced so I decided to shop around. The threads for the cap are the old fashioned Girling/Lucas ones and the master cylinder is made by AP Racing. I could easily get a cap that would fit from any racing car supplier - hell you can buy a genuine Girling one from Demon Tweeks! The problem is that mine's a road car and it needs a fluid level warning switch (it doesn't strike me as a bad idea on a racing car even if it's not a legal requirement). The warning switch is integrated into the cap. I refuse to believe that Caterham are making their own reservoir caps, so the question becomes: where did they find a brake fluid reservoir cap that will fit an elderly British car, or a racing car, but has a fluid level float switch built into it?

Half a day of googling later and the answer is obvious: Late model classic mini. When they started making minis they would have been using Girling master cylinders, or something compatible. At some stage the law changed and they had to have a warning light for the fluid level, they didn't change the master cylinder, they just cut a hole in the cap and bodged a crappy float switch into it. The part number is GRK6009 and they're available from all the people that look after old minis. It looks like a rush-job, the design is terrible and the lands for the gasket are tiny. Frankly I'm surprised that it kept the fluid in for this long. I'll probably make my own out of a real cap and a modern float switch when I take the car off the road at the end of the year.

Richard "Yes I do believe that I can make a better job of it that Austin-Rover" B

Oven Pride

I hate household chores at the best of times and one of my least favourite is cleaning the oven. That particular chore has just got even more annoying because of the brand name of the cleaner that was for sale in the Co-op.

In this photo you can also just about see my Joy Division oven gloves (I've got Joy Division oven gloves).

The magic of human memory and the way that a song can get stuck in your head means that now, cleaning the oven has a terribly annoying 80s soundtrack running around in my own head.

Richard "That's what my heart yearns for now" B

Greener Light Harpoon Gun

The human consciousness is a tricky beast. It makes you feel like you're in charge the whole time whereas in fact most of the time it's making up excuses after the fact. "Why did you put your foot under that?" "I sort of thought I could stop it breaking after I dropped it." (it was fragile china or a heavy television). "How was the drive?" "Errm, I don't really remember getting here". Our picture of ourselves is made up of stories, most of them heavily embellished, but just sometimes you can find yourself doing something or getting somewhere and you can't make up a story for why you're there. "Why did I just come upstairs? I think I wanted to get something, never mind I'll go back down".

I've had a lot of time on my hands and I've been watching a lot of videos on YouTube. If you watch one video on a topic, the stupid algorithm will assume that it's your new obsession and recommend nothing else. I've been down myriad convoluted rabbit holes of information, and even though I have no interest in firearms I've so enjoyed the knowledge and enthusiasm of a couple of American gun-nuts that I've watched a lot of their videos. During a serious review of a collectable light harpoon gun (Yes the one used in "Jaws") the presenter managed to make me laugh with a fairly subtle "Jaws" reference.

"The manual contains no information about boat sizing"

https://youtu.be/BAxKFLh61Yc?t=399

I sent it to my friend, who also laughed, but then he asked me "Why were you watching a review of a harpoon gun?" and I couldn't really answer. I mean I remember enjoying a gun video on that particular channel, and I know that I've been watching several of them to pass the time, but how did I end up watching that first one? No Idea. It might have been something to do with military history? Some of the aeroplane videos I watch talk about their guns, maybe that was it? It probably didn't follow from motorcycle reviews or track day footage.

Richard "This was no boating accident" B

Curiosity Killed the Cat

One of my colleagues works with artificial intelligence and machine learning. One of the time-series datasets that we've got access to, and that he'd like to make predictions from is about leisure centre bookings. He's been doubly screwed by the corona virus, not only is he locked up at home, but his data has an unexpected cliff edge in it, and all the predictions are meaningless.

My mum's cat did even worse. My mum rescued it from a neglectful junkie at the beginning of 2019 and it has blossomed from a scrawny terrified creature into a well fed, friendly and bossy companion. When all the traffic died down it started crossing the road and exploring the neighbourhood. Last week, on its way home it was hit by a car and killed. I buried it in the garden last week. Digging a hole big and deep enough to give a cat a dignified burial is surprisingly tiring, but it's also very compelling. You can't stop if the hole isn't wide enough for the cardboard box/ coffin, and you daren't stop until it's deep enough that you're absolutely sure that your old friend won't get dug up and eaten by vermin.

When I was in my late teens or early 20s I dug the grave for my favourite cat, and we planted a bay tree in his honour. This latest cat was granted a grave site surprisingly close to the Willy-cat memorial bay tree. I do hope that they aren't fighting over territory in the afterlife.

Richard "sexton" B

Under Pressure

As I now ride a tiny little lightweight bike with cheap little tyres I was persuaded that I could and should change my own tyres at home. I spent £10.80 on tyre levers, gave it a try and failed.

Yet again my crappy arbour press came in handy, this time as a bead breaker. "I am become useful, the destroyer of seals."

I levered the old tyre off without any problems.

I put the new tyre on without any problems.

I couldn't get enough airflow to seat the beads with my footpump.

The machine at he garage did no better.

I turned another wheel into an receiver, pumped it up to 60psi by foot and connected it to my wheel. Still no luck.

I turned the pressure vessel of my week sprayer into a similar contraption and failed again.

Eventually I had to ask for help, and completely negated the point of the whole exercise.

I could just go and buy a little compressor, but I don't think it would help. You need a huge receiver and high flow rate couplings and hoses. The helpful man at National Tyres said that their compressors are set to 200psi and blow down a hose as thick as your finger.

My spite filled research led me to another technique for mounting a tyre: A small explosion. People are successfully mounting tyres in an emergency by setting light to a ring of brake cleaner or cold-start sprayed into the rim.

Even by my standards this is a bit dangerous and a bit rough. I have been researching nice safe butane explosions and I've built both a butane deliver system and a piezo igniter that will fit through an automotive valve stem.

Here it is successful test of using it to open a shoe box.