Name Plate

A few years ago, one of Kay’s kids gave her a scroll saw cut wooden name tag which she’d displayed in her classroom ever since. Due to the ridiculous nature of our surname it’s a bit long and hence fragile, and it’s broken a couple of times.

I’ve recently had to cut down an old mountain ash that’s been growing in our front garden ever since the house was built. I suspect it got its roots a few inches down and found the awesome clay that everything sits on round here. Suffice to say it did not thrive and its constituent parts have been seasoning for a while in the garage.

I figured it would be nice to use some of it as a mount for Kay’s name plate so I stripped the bark off and generally neatened it up a little with a bit of carving and sanding, and then I shaved off a couple of flats with my hand plane; one for it to sit flat on, and another to mount the wooden name plate. A bit of oil and Bob’s your uncle.

New Workbench

A month or so ago I completed Phase 1 of my epic plan to re-build the man cave (otherwise known as The Hall of Half-built Curiosities). I’ve been using a pretty bog standard Ikea desk since God were a lad and I’d always wanted to custom build something a little better suited to what I needed. So I stripped everything out and dumped it all in a huge pile in the bathroom (which made Kay deliriously happy I can assure you) and started hacking up bits of 2×4 and huge sheets of MDF.

Top tip number one folks: never, ever, buy timber over the interwebs ‘cos they’ll pick the twistiest POS sticks out of the entire stack for you. I’m surprised the ones I got even had the birds and squirrels removed. Every cloud though… I now know how to tune a hand plane and how to use winding sticks to turn Disney princess castle turret handrails into straight, though admittedly somewhat thinner, things. Of course it would have made much more sense to sack ’em off, barbecue some nice steaks and just buy some straight ones but where’s the fun in that?

I wanted the supporting structure to be nice and open with no legs to get in the way. I pretty much managed that but had to put a couple of glued up 4×4 props at either end of the bench. The remainder of the support comes from 2×4 wall plates bolted to the masonry walls with hoooj hammer fixings. In the end, the thing is pretty much bomb-proof and easily takes my weight without any sign of movement; way more solid than I had hoped for.

I’ve covered it using a couple of 8×4 sheets of 18mm MDF which I managed to get pretty much bob on when it came to level and joins. I even jigsawed some curves on the ends to make it nice and purdy. Oh yeah, I cut out some holes for cabling as well. Turns out my poor little Black and Decker does not like three inch hole saws. Some of the magic smoke definitely escaped and I had to leave it outside for while as it had become something of a fire risk.

The next job is to build some under bench storage; probably just simple MDF boxes with doors and casters. After that I’m planning on putting up some French cleats on the walls so I can put up custom and adjustable storage type stuff.

Really pleased so far. It’s not fine carpentry by any means but that’s not what I want. I want something beefy that I can get paint and glue and grease and solder and coffee and sweat and blood and tears and kitten guts on. No. Not kitten guts. I mis-spoke.

Garden Carpet Moth Pays a Visit

Sometimes there’s just not enough hours in the day. Yesterday we were busy doing the usual everyday stuff in the back (picking up dog poo, putting out the rubbish, living the dream) when Ellen goes all Disney Princess and has a little moth land on her finger.

It was one of those common-or-garden small-ish, grey-ish, boring-ish ones that you see all the time. Kind of the moth equivalent of the Little Brown Job. But it occured to me that I should probably find out what it was. Turns out there are a lot of moths that look just like this one but this is, I’m pretty certain, a garden carpet moth. Never heard of it. Which is kinda sad really.

So anyway, when you’re trying to identify moths (and flowers, and trees and birds and pretty much anything) it turns out you need to have at least a little bit of an idea of what you’re talking about. So I ended up hitting up Wikipedia to find out things like “Does the term ‘forewing’ refer to the front part of the wing or the front wing of a pair of wings?” and of course I end up doing the usual Alice down the rabbit hole schtick.

Turns out ‘costa’ is not just everyone’s favourite go-go juice dealer but it’s also the name of the vein that runs nearest the front edge of an insect wing. At least according to the Comstock-Needham naming convention. Who knew? Well, now I do and you do too.

Not enough hours in the day.

False Widow

You know when you look at something and your gut says “Hmm. That’s weird.” Pretty sure this is a false widow spider.

Pretty sure these are not supposed to be in my garage. And I’m damned sure Ellen won’t think they’re supposed to be in the garage.

Book Review – The Works: Anatomy Of A City

Cover Photo
If you can’t walk past a hole in the street without leaning over the edge to see what’s down there, then this book by Kate Ascher will tickle your fancy. It tells the hidden story of New York’s infrastructure covering everything from airports to sewage.

Road Junction Layout Types

It’s light enough to be an easy read without getting too bogged down in the details and it’s well illustrated throughout. Personally I would have preferred a bit more detail on the engineering side of things which I think could have been brought in at the expense of some of the more New York specific historical stuff. Definitely an interesting read though.

Childhood Objects

Well I’m going to borderline cheat here. Does teenage still count as childhood? It does? Cool. I guess like most, I’ve got quite a few well and fondly remembered childhood objects but my stand-out has got to be my touring bicycle. Just like this one.

Dark green Raleigh Royal, super lightweight (for the day at least), super strong and super comfy. Talk about an enabling technology, I pretty much lived on this thing in my teens. I went to a big private school with a wide catchment area so mates, and **far** more importantly, girlfriends, were pretty spread out. My trusty steed let me get there quick smart. See that rack over the back wheel? Hang a pair of panniers and a bag on that, phone my best mate Dave, grab a few tools, some cash, food, pans, stove, kipper and tent and off we disappeared for a couple of days or a couple of weeks. Wherever. We. Wanted. To. Go. Man alive, that thing was liberating. We once went down to Land’s End in Cornwall and then rode the entire length of the UK to John o’ Groats in Scotland.

That’s me on the right, next to my mate Dave, with my Dad and his mate Bryan at the front. We’re all celebrating with a tiny bottle of single malt each.

Build A Computer From Scratch (Kinda Sorta)

I’m currently part way through a fantastic course on hardware design. It’s called Nand2Tetris and walks through building a simulated computer from the very simplest components (individual transistors) right through to a fully functioning computer. There’s a subreddit available if you want to chat with some fellow learners and a TED talk covering the course and some of the educational ideas behind it.

Everything runs in a simulator so there’s no actual hardware to buy or break or futz about with (which you may or may not find attractive) and this means you can focus on the underlying theory and understand what’s going on rather than getting bogged down in implementation details.

Still early days (I’m busy building some of the more complex components from basic logic gates at the moment) but it’s very good so far. No previous experience is required, but if you have none, be prepared to do some fairly serious thinking and maybe a bit of background reading along the way.

Update 2016-03-26:
All done now. I really liked this course. It had great pacing and a really good overall shape that kept my interest all the way through. There was plenty of detail without any tedious busy-work and it covered an awful lot of ground without feeling overwhelming at any point. While this little short course in no way represents the realities and complexities of a real world project it did provide a great insight into what kinds of issues are involved in computer design. The projects all required some thought but built on previous knowledge very well and there was a definite sense of accomplishing something really quite significant for the relatively small amount of effort involved. 10/10 would recommend.

Hacking Lego Motors

Lego Technic Power Function motors are nice and easy to hack for robotics projects – in large part because they come with a built in gearbox so you get nice amounts of torque at low speeds right out of the box.

Here’s a quick breakdown of what you need to know. The tl;dr is that you apply a 9V PWM signal to the two inner cores of the ribbon cable. The outer two cores are not connected.

I’m using the M Series 8883 motor but there are plenty of alternative choices available. I’ve not tried them but I would assume they all use the same pin-outs.

The motor is supplied attached by a four-way ribbon cable to a lego electrical connector:

Motor and Connector Combinaton
Motor and Connector Combinaton

You can either snip this cable in the middle and solder the individual cores or you can sacrifice a simple lego PF extension cable instead and leave your motor assembly intact.

The Lego PF system uses a standard pin-out system across all the products but note that for our purposes here we only need the C1 and C2 lines (the 0V and 9V lines are not connected inside the motor).

Here’s a photo of the motor end showing the pin-outs:

Motor End Pin Assignments
Motor End Pin Assignments

And here’s the pin-outs for the connector end. Which you might need if you’ve just cut your motor cable in half without making a note of the cable orientation…

Connector End Pin Assignments
Connector End Pin Assignments

If you’re interested in the internals, undo the small crosshead screw

Underside showing housing retention screw
Underside showing housing retention screw

then prise off the housing using a small flat-bladed screwdriver trying not to stab your fingers and thumbs in the process

Housing retention tabs
Housing retention tabs

Once that’s off you can pull off the gearbox (which itself comes apart very easily to reveal a set of three planetary gears):

Gearbox removal
Gearbox removal

Finally you can slide off the inner housing to reveal the motor itself and the small smoothing capacitor.

Internals
Internals

You can then see that the outer two cores (0V and 9V) are not connected to the motor internally. So, you control the motor by putting 9v on C1 and 0v on C2 to spin the motor anti-clockwise as seen from the outside, or alternatively put 0v on C1 and 9v on C2 to spin it clockwise as seen from the outside. To control the speed, apply a 0 to 9V PWM signal of the required duty cycle on the logic high control line. In terms of current draw, my M series motor pulls about 70mA when free running and up to about 500mA when I really load it hard. Bottom line – you need a controller circuit to run this, you can’t just hook it up to a micro-controller’s digital out lines.

Pre-assembled Test LEDs

Here’s a nice little idea I saw somewhere a while ago and have just got round to making. It’s just an LED in series with a 470Ω resistor connected to a pair of 0.1″ pitch posts. Whenever you need to quickly check a signal on a breadboard you can just plug one of these babies in and you’re done.20160220_065025