Category Archives: Blog

General thoughts on life, the universe and everything. Stuff that doesn’t fit in the other categories!

Send in the clones!

So here’s the thing that drives me crazy.

Having had a hard disk die on me a few years ago, I’m a little paranoid about backups. I have three:

  1. Time Machine, over WiFi to a Synology NAS
  2. Backblaze, “cloud” backup over the internet
  3. SuperDuper clone to an infrequently connected USB hard disk

Time Machine and Backblaze run all the time, nice, seamless and hopefully pretty complete. I do the SuperDuper clone occasionally and every few months I try to reboot and check that the clone actually works.

And that’s where the problems start.

If I forget to turn off WiFi — which I almost always do — then when the clone starts up, it immediately connects to WiFi and starts to back up to Time Machine. I panic and stop it as soon as I realise.

But then I boot back to my main disk and… Time Machine decides it needs to do a full backup. Which. Takes. Forever. (Backblaze is also doing a huge backup, presumably for the same reason.)

What’s the answer to this? Is there a way to switch off WiFi on the clone automatically? Only start when the boot disk has a specific name? I don’t know! It’s hard to search for because I can’t think what the answer might be.

Earth Day Cynicism (Not mine)

Earth Day bugs me.

Okay, not Earth Day itself. The idea of respecting and preserving the world is difficult to argue with. No, what annoys me is all the big corporates jumping on the bandwagon just to be seen to be there. 

These companies do, effectively, nothing, or at least nothing actually useful, just to say that they’re supporting Earth Day. It’s worth talking about a couple of examples.

My employer had committed to turn off the lights that illuminate the logos on all its buildings for our lunch hour. They also suggest that we turn off unnecessary computers and other equipment for the same time. They generously suggest that home workers to do the same.


Why not turn off the lights for the whole day? Why not have signs that don’t need power all year?

Apple, on the other hand, actually do a pretty good job environmentally, considering that they manufacture stuff which is inherently nasty. Not to say that they couldn’t do better, but they claim 100% energy for the US comes from renewables for example.

But even they fall for pointless symbols. All their retail staff were to wear special green t-shirts. How environmentally friendly is it to print thousands, possibly tens of thousands, of shirts to be worn for a single day?

There are lots of other examples. They might argue that these things are significant at their scale. Or that their feeble offering do mean something as it increases awareness. 

But wouldn’t it benefit everyone if they actually did something that protected the environment all the time? The marketing team glomming onto a genuine movement just to get positive press is incredibly cynical. Being genuine would be much better press. 

Otto: Assembly

With all the pieces printed or purchased, it was time to assemble Otto.

Since I’d already tested the Arduino and enlarged the holes for the eyes and stepper motors, the process of putting it together was actually fairly uneventful.

Putting Otto together

Because of the small size, some parts were very fiddly but it wasn’t hard per se. Kudos to the people who put the instructions together!

I came across three minor problems.

First, I pushed one of the screws in too far, so that it looks as though it has a small horn. I almost did the same thing on the other side so it would, at least, look symmetrical. It’s not a big deal but I know it’s there! It’s not worth re-printing the head for so I’ll have to live with it.

Second, the battery pack hasn’t arrived yet so I had to run Otto only when connected to power via USB – a computer works but so did the power brick from our Amazon Fire tablet.

Finally, as I speculated, I think I ordered an incorrect part. Fortunately it was only the buzzer so it isn’t critical. I’ll probably try to fix this soon.

(The buzzer I have didn’t have polarity labels – which I’m not sure is important – and wouldn’t stay put on the end of the cables – which I know is a problem!)

With the robot assembled and its head snapped into place, the next thing to try was powering it up and seeing it dance and avoid obstacles.

Had I not played with the electronics separately I probably would have freaked out and assumed it wasn’t working. As I found, it takes a few seconds to download the software and reboot and, unlike before, I couldn’t see any of the lights flashing as they were all now inside Otto.

My patience paid off and he started dancing on the first try. The kids, who had lost interest during some of the more intricate fiddling around that was required earlier on, were suddenly excited again. Actually, make that kids of all ages were excited!

I was impressed that it worked on the first try. The dancing is pretty cool. At one stage I’m its routine it tries to stand on tip-toes and falls over every time. I suspect it would have to be very finely tuned for that ever to work. One of his legs could do with a little calibrating but it works well enough.

Next I uploaded the “obstacle avoidance” program. I found this a little less reliable than the dancing, but it did walk, then stop and tap its foot when you wave your hand in front of its eyes. Looking at the code, I wonder the buzzer adds something?

Overall, it was a great little project. “It works” is a pretty boring conclusion, but it’s true. I expected far more to go wrong. I’m happy that it didn’t.

Otto: Electronics

The first stage of building a dancing, obstacle avoiding robot was to build the body and legs using my 3D printer. The second was to test the electronics before assembly. This would prove to be more eventful than the printing.

I was least sure about all the electronics. They components arrived and… they sure looked okay. I didn’t think the buzzer looked quite right — it looked too big, but I figured that it even if a little lose it should make something approaching a buzzing noise.

The computer itself arrived poorly packaged, with a bunch of the pins bent. I managed to right them without breaking anything.

Arduino Nano, IO Shield, obstacle detection (eyes), motors

And talking of breaking things: I plugged in the Arduino and… nothing. Eventually I realised that I needed to install a Serial-USB device driver. The Otto download came with a CH341 (as it’s creatively called) driver so I installed it, rebooted and… well, when you see text scrolling up the screen when you boot your Mac, either you accidentally jabbed command-V or something bad is happening. In this case, the latter.

Anyway, after a fair degree of panic and dread at the idea of finding and installing another kernel driver from a random website, I found one that seemed to work.

I tried the Arduino before bundling it into the plastic body just to make sure I had the fundamentals down. I plugged in the IO Shield and one of the motors. I press “Upload” in the Arduino app and… seemingly nothing at first. Then blinking. Then the motor started whirring rhythmically.

I picked out a few other example apps and tried those. The best one, at least in the sense that it proved that I was doing the right thing, just blinked one of the boards LEDs. It looked like it worked, so I changed the delay from one to two seconds and saw that that worked too.


Now all the bit are made and shown to be more or less Known Good, it’s time to assemble Otto.

Otto: Printing

The first stage of building a dancing, obstacle avoiding robot was to build the body and legs using my 3D printer.

Surprisingly, for someone who has been playing around with computers since I was eleven but only had a 3D printer for a month, I was much more worried about the electronics than the actual making stuff.

So confident, in fact, that initially I placed all six pieces into one print job.

Then I chickened out. I switched to four prints: the body, the head, the feet and the legs, in that order.

3D printed head, body and legs.

In one sense, I need not have worried. All the pieces came out just fine, though it took longer than I anticipated. The body, I naively guessed, would take two, maybe three, hours. Nope. Nearly eight!

Suitably chastened, I allowed ample time for the others.

The head and the body connected together with a satisfying snap. Things looked a little worse when I tried to place the electronics inside. The IO Shield fit in so snugly that I was worried that I wouldn’t be able to get it back out. The “eyes” and the motors didn’t quite fit in at all. The apertures were just slightly too small.

I worried how much surgery would be required, but in the end a little scraping around the edges with a sharp knife did the trick.

Overall: fairly straight forward. Next: the electronics.