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Sunday, December 21st, 2014

Subject:Matiu
Time:10:28 am.

Originally published at Happyinmotion. Please leave any comments there.


Monday, October 27th, 2014

Subject:Living roof for the shed: Which plants are still alive?
Time:8:25 pm.

Most of them, it seems. Currently, nineteen out of twenty-one haven’t kicked the bucket.

Here’s what the roof looked like as planted, back in May.

And today:

Currently exploding are the carex secta, virgata, and fagillifera, at the top of the roof in the driest and windiest part. Down at the bottom of the slope, the pratia angulata/panekenake seems very happy. Somewhere in the middle is the leptinella, coprosma prostrata and acerosa, doing quite nicely, although the acerosa is pretty shaded by the trees to the north. The ferns in the darkest and wettest far corner are not dead yet. One of the muehlenbeckia complexa/puhuehue died straight away, the other is hanging in there, despite being in similar conditions. One of the hebe albicans got heavily shaded by a branch before I cut that back and looks like toast, the other is fine.

This suggests to me that the tussock will survive on the house roof, so I think we’ll plant some next winter. It’ll be good to see it standing proud over the low succulents and seddums. The only other tall stuff we have up there is hebe stricta, which I like, but grows everywhere and gets so big (above head height) that it’ll fall over in the thin soil on the house roof.

Originally published at Happyinmotion. Please leave any comments there.


Tuesday, October 21st, 2014

Subject:Mitochondrion Mark 5.0: First light
Time:9:53 pm.

Yeah, this is going to be bright.

That’s the test power board, the test centre board, and the test strip. The power board holds four 16340 Li-Ion cells and a 5 Volt, 4 Amp converter (and some other gubbins). There’ll be four of them, one for each strip. The centre board holds the Teensy, motion sensor, FRAM, and level shifter (and a bunch of other gubbins). The test strip is 144 Neopixels. There’ll be 800 of them.

Testing reveals a bunch of issues to fix, but at least I’m at the stage of making light.

Originally published at Happyinmotion. Please leave any comments there.


Wednesday, October 8th, 2014

Subject:Mitochondrion Mark 5.0.1 progress: almost enough LEDs
Time:6:34 pm.

The answer to the question “how many LEDs?” is always “moar!”. However, I think this counts as “almost enough”:

And you’ll note from the change in version number that the Mark 5.0 power design didn’t work out. The Mark 5.0.1 power design is underway. In short, while I could fit 18.2 mm diameter cells into a 19.6 mm space which also holds circuit boards and wiring, “could” is not the same as “should”. Hence the delicate trade-off of diameter, length, weight, energy, power, charging, balancing, and not catching fire means that 16340 cells are looking better than 18650s. This will result in downgrading the peak power output from “portable apocalypse” to “merely seizure inducing”, but you can’t have everything.*

* – Well, to be precise, you can have everything, but a large fraction of everything is planned for release in future versions.

Originally published at Happyinmotion. Please leave any comments there.


Subject:Mitochondrion Mark 5.0.1 progress
Time:6:34 pm.

The answer to the question “how many LEDs?” is always “moar!”. However, I think this counts as “almost enough”:

And you’ll note from the change in version number that the Mark 5.0 power design didn’t work out. The Mark 5.0.1 power design is underway. In short, while I could fit 18.2 mm diameter cells into a 19.6 mm space which also holds circuit boards and wiring, “could” is not the same as “should”. Hence the delicate trade-off of diameter, length, weight, energy, power, charging, balancing, and not catching fire means that 16340 cells are looking better than 18650s. This will result in downgrading the peak power output from “portable apocalypse” to “merely seizure inducing”, but you can’t have everything.*

* – Well, to be precise, you can have everything, but a large fraction of everything is planned for release in future versions.

Originally published at Happyinmotion. Please leave any comments there.


Sunday, September 21st, 2014

Subject:Mitochondrion Mark 5.0 progress: the bit that I’m supposed to be good at…
Time:10:01 pm.

Measure twice, cut once, swear loudly, and measure again like five times…

So one of the goals for the Mark 5.0 is for all the bits just to fit together accurately and quickly. The structure for the Mark 4 was passable but there was plenty of bodging. Instead, the Mark 5 would have a far-more thought out design. So then:

Nice and simple. Aluminium strips, held together by 3D printed nylon bits. The aluminium was rectangular and flat, the 3D printing bits had all the accuracy designed in with lots of location holes. Just tap and screw it all together.

Cake.

Well, the reality ended up being:

Of those bits, I think one part is correct and usable. The rest is junk. I could call that a waste of several days, or I could think about how much I’ve learnt from trialing this design. Like:

  1. Never try to locate holes by hand if they need to be accurate to within less than a millimetre. Or two. Three on a bad day. Draw up a drilling jig and get it printed in stainless, coz that will cost less than the value of the parts you’ll waste by drilling holes in the wrong place.
  2. Check all the drawings. And then sleep on it and check them again. Coz somehow, a quarter of the pairs of holes that should have been 17 mm apart ended up 14 mm apart.
  3. Tolerances are hard.
  4. Try to avoid designing holes that need three tools to create, especially in aluminium less than a millimetre thick. Also, countersinks really really really need depth stops.
  5. Don’t tap anything when you can just design in a recess to hold a nut.
  6. There may be such a thing as a 40 mm long M2 grub screw, somewhere, but you’re a fool to make a design that needs one.

At least when debugging structure, you can tell if you ballsed it up, coz you screw it all together and it just doesn’t fit. So yeah, it’s time to design the Mark 5.0.1.

Originally published at Happyinmotion. Please leave any comments there.


Thursday, August 28th, 2014

Subject:Mitochondrion Mark 5.0 progress
Time:7:30 am.

The power output for the next version of the Mitochondrion glow staff is approaching the level you’d use for an electric bike, hence I’m taking battery management seriously. The current plan is to use a dedicated battery level gauge chip. The Linear LTC2943 looks like it will do the job, except it is 3 mm square, with no legs to solder to, just tiny pads under the chip. It’s designed to be soldering in factories with proper kit, not by a muppet like me with a soldering iron.

So WTH, watch a tutorial, mount my phone as a microscope, flip the chip on its back and deadbug it to a breakout board. How hard could that be?

Really quite hard, it turns out. Got there in the end though.

I know, it doesn’t look great, but it checks out. Everything that should be connected is and everything that shouldn’t be isn’t. I’ll test that the chip is actually working once a few other bits arrive.

Originally published at Happyinmotion. Please leave any comments there.


Sunday, July 20th, 2014

Subject:Still winter, still tidying
Time:9:27 pm.

I am still in hibernation mode, which means finishing projects off (like the desk) and tidying up (like the workshop).

Every so often, I think it is helpful to write down your goals in life. Currently, I only have two goals:

  1. Put things in boxes.
  2. Put labels on boxes.

So workshop now looks like:

For reference, this was a month ago, full of crap and a bloody big desk:

I know! Floor space! Sexy sexy floor space. I’m going to dance around naked stand in the middle of the void, stroking my chin and contemplating potentiality.

And if you think this is all a displacement activity to stop me from getting on with the Mitochondrion, Mark 5, then you’d be a little bit right. Still, I think I’ve worked out how to do the hard bit that was holding me up, so there can be progress on that too.

Originally published at Happyinmotion. Please leave any comments there.


Thursday, July 10th, 2014

Subject:The very, very, very long tail of e-commerce
Time:2:57 pm.

Three years after making it available, I have just sold my first 3D printed metal part:

It’s a replacement locking pin for a Triton Mk3 workstation. It retains the table when you shift modes from cross-cutting wood to ripping.

Clearly, either very few people are using Australian DIY equipment from the 1980s or that Triton owners are not complete idiots who lose their locking pins.

This says something about the long tail of e-commerce and how we will all do business in the Twenty-First Century. I’m just not quite sure that something is.

Originally published at Happyinmotion. Please leave any comments there.


Subject:The desk
Time:1:05 pm.

Finished the desk at the weekend. It took four of us to install, given the weight and close fit, and much scratching of heads and rehearsing to not leave gouges in the floor, walls, or ceiling.

I think that turned out not too bad.

Originally published at Happyinmotion. Please leave any comments there.


Subject:Theraputic sharpening
Time:11:46 am.

When I’m under the weather, I potter about, fettling what needs fettling. That resulted in sharpening chisels and the hand plane.


(Click to enbiggen, if you’re really into scratch patterns.)

Plate of glass, emery paper, and a rolling jig. They’re not mirror-perfect, coz I’m not quite that obsessive, but decently sharp.

Turns out my phone makes a passable microscope, provided there’s enough light. Sadly, I did these last night. Now there’s sunshine I can now see the bits I missed, while not having the energy to fix them.

Originally published at Happyinmotion. Please leave any comments there.


Sunday, June 8th, 2014

Subject:…still sanding…
Time:8:03 pm.

And this is after I caved and bought a belt sander for the roughing, coz the wood is seventy year old macrocarpa and hard as.

Originally published at Happyinmotion. Please leave any comments there.


Saturday, May 24th, 2014

Subject:This weekend, I will mostly be sanding this piece of wood
Time:1:52 pm.

Yeah, and next weekend too.

Originally published at Happyinmotion. Please leave any comments there.


Monday, May 12th, 2014

Subject:The house is in this month’s New Zealand Life & Leisure
Time:7:49 pm.

As ever, they’re focusing on the green roof. If you want an environmentally-friendly house, then a living roof is way down the list of things you can do. Insulation and double glazing are probably top of that list, but an article about a house with insulation and double glazing is not exactly going to get people to buy magazines.

Anyway, it’s two more pages pushing the idea that houses can sit lightly on the land and be warm and dry and healthy.

Originally published at Happyinmotion. Please leave any comments there.


Monday, May 5th, 2014

Subject:A living roof for the shed
Time:4:37 pm.

I wanted to put a living roof on the shed, to match the house, to reduce the visual impact of the shed upon the neighbours, but mostly replace the natural habitat taken away by the shed.

The roof on the house has been just fine, although we have some weeding to do. For a shed, rather than a house, we could do something simpler, while using up left over wood and soil. To hold the soil against the slope of the roof, there is a wooden grid. To stop the soil washing away while still letting water drain, there is weed mat and holes bored in the horizontal grid members. I might have got carried away making the grid up, it really didn’t need angled pocket screws, but WTH. The grid is held in place by some stainless strapping over the roof edge and the handy nearby concrete wall.

I only want to build this once, so I want to do it right. That means making it strong enough and preventing corrosion… and the shed has a very flexible steel roof. Whoops.

The roof is going to be carrying about a quarter of a tonne of wet soil. On top of a wooden shed. In an earthquake zone. That’s not good and I don’t want all that coming down on someone’s head. Hence all the uprights in the shed have been at least doubled, there’s three more purlins, and rafters fitted every 400 mm. I used a deflection-limited approach to the structural design, which is a technical term meaning that I jumped up and down on top of it to see how much it flexed under 80 kg. It didn’t. And then after loading it up, I put a straight edge against to rafters to see how much they had bent. I couldn’t detect any bending, so I think it’s good.

As for corrosion, the shed roof is coloursteel, so half a mil steel, galvanised with lots of zincalume, and baked on paint. It’s warranted for fifteen years, even in salt spray zones. (Yes, we’re in a salt spray zone, despite being 150 metres up and three kilometres inland. We’re inland from Cook Strait, which is one of the roughest and windiest pieces of water in the world.) So it should be good, right? I mean, that’s what nearly every house in NZ uses… although it keeps plenty of people employed replacing roofs every few decades.

So first up, all the roofing nails got a coat of primer and epoxy paint. As did all the scratches that happened while installing the roof. Oh god, so many scratches…

Coloursteel is great if it gets to dry out every so often and the rain washes the crap off it on a regular basis. Sadly, it shouldn’t be used in contact with permanently wet materials or soil, which is a bit arse for a roof that’s going to be covered in soil. The steel roof is also going to be impossible to inspect for rust without digging up the plants, leading to a possibility of the whole thing collapsing on someone. So to keep it from rusting, there’s a layer of polythene directly on the steel, doubled over so that staples holding the top layer to the wood are separated from the steel by the bottom layer of the film.

For good measure, the top edge of the poly is also siliconed against the steel, to stop water running down between them. I probably should have put a flashing over that edge, but we’ll see how it goes.

The poly is protected by weed-mat, which also covers the drain holes in the horizontal parts of the grid.

For the plants, I ended up scratching my head somewhat. The micro-climate on the roof varies from sunny to shaded. It’s in a damp spot that gets plenty of rain, but with the thin (100 mm) soil it’ll vary from moist to very dry. And then there’s huge amounts of wind, coz this is Wellington. In the end, I just used Greater Wellington’s regional plants guide and chose the toughest natives from a bunch of ferns, low cover, and sedges.

From left to right: carex secta, carex virgata, hebe albicans, coprosma prostrata, asplenium gracillimum/hen & chicken fern, blechnum discolour/piupiu, muehlenbeckia complexa/puhuehue, coprosma acerosa, leptinella diocia, carex fagillifera, pratia angulata/panekenake. And then there were some extra leptinella from the house roof of a different kind, which seems to do very well in shady spots.

These ended up spread across the roof, with the ferns to the north in the shade of the tree and the sedges to the south where it’s more exposed. I’ve no idea what will survive, but plenty of weed mat and bark mulch should help.

Mostly, I like that from above you can barely see the shed at all. From the front, the sedges stick up over the roof and the coprosma should creep over the edge of the roof-line, helping the shed to blend in. And hopefully, it’ll last a good long time. Ask me in a decade or two how it’s going.

Things I screwed up:

  • If you don’t want anything to rust, use stainless fasteners, right? Nope. Stainless is good on its own, galvanised is good on its own, put the two together and you’ve made a battery. The zinc gets eaten by the stainless. The straps that stop the whole thing sliding down the roof are stainless and they’re screwed directly to the galv. Bother. I’m going to have to put some non-conductive plastic between them and replace the screws with plastic rivets.
  • I don’t think the weed mat will blow away, but we’ve a 120 k storm developing today, so I guess I’ll find out. I should have put some rocks around the edge.
  • I planted the tall sedges right next to the solar panel for the shed internal light. I’ve enough cable to raise the panel up by a metre or two, but that was dumb.

Originally published at Happyinmotion. Please leave any comments there.


Wednesday, April 16th, 2014

Subject:Further tidying and sorting out
Time:10:11 am.

The bag on the right is a Timbuk2 Classic messenger bag. I’ve had it for fifteen years and I’ve used it just about much every day. It has done pretty well but is starting to die.

The bag on the left is the replacement, also a Timbuk2 Classic messenger bag. I expect it to last a while.

Originally published at Happyinmotion. Please leave any comments there.


Tuesday, April 15th, 2014

Subject:Winter, therefore tidying up
Time:10:49 am.

Winter’s kicked in, so I’ve switched modes into finishing things off, tidying up, and getting generally tatted down and squared away.

So, the Too Bright Hat needed a new cable. 3-pin mini-XLRs seem to be the right balance of durable, small, and able to handle 8 Amps, but finding connectors with decent cable clamps took a while. The Hat is on my head and the driver is on my belt, so there’s plenty of flex and tension on the cable. Without clamps, that stress results in:

Ended up with the REAN Neutrik ones. Of course, no-one in NZ stocks them, which is a shame as they’re good and solid.

The Hat driver had a LiPo with just a fuze for protection, along with low Voltage cut-out handled by the Teensy, which is a bit shit. Charging the battery required taking the battery out of the box because it’s also kind of crowded in there and there’s no room for a charging port:

That yellow connector is an XT-60, good for sixty Amps, making it ten times as big as needed, and that black fuze is bloody huge too. So I swapped that all out for some EC3s and a proper PCM board, freeing up lots of space. Of course, I filled it right up with banana sockets for the charge and balance connections so I can charge the battery in place.

If I can do what I want to do with the Mitochondrion Mark 5, then it’ll be pulling peaks of 50 Amps. Inside a one inch tube. Fitting all that in is going to be fun…

Originally published at Happyinmotion. Please leave any comments there.


Sunday, April 6th, 2014

Subject:Wellington on a good day
Time:6:18 pm.

Originally published at Happyinmotion. Please leave any comments there.


Sunday, March 16th, 2014

Subject:Three-up thigh shoulder stand thing
Time:6:36 pm.

I saw a two-person version in that video that everyone watched this week and thought to myself, more looks feasible.

I have no idea what this move is called. It’s not in the three person sports acro list. I’m going to call it “Andrea & Wendy doing shoulder hand-stands on my thighs”.

It’s actually cake for the base but surprisingly bent for flyers.

Originally published at Happyinmotion. Please leave any comments there.


Sunday, February 9th, 2014

Subject:Testing level shifters for running Adafruit NeoPixel strips from a 3.3 Volt Teensy
Time:4:29 pm.

If you’re running NeoPixel LED strips off a Teensy 3, maybe because you want to put 180 LEDs on a hat, then you need a level shifter. But which one? The NeoPixel data protocol is high speed and pretty harsh on timing requirements and I’ve had a bugger of a time getting reliable data from the Teensy to these strips. Hence I’ve tested a bunch of shifters. I tried a TXS-0102, TXB-0108, 74HCT245, PCA9306, and a MOSFET based shifter.

The Teensy outputs data at 3.3 Volt, the strips expect 5 Volts. Or rather, the strips might see 3.3 Volts as a digital 1 or they might not. If you want some reliability, then you’re better off shifting the Voltage level up to 5.

Each LED reads the data it needs and passes on the rest, regenerating the signal to nice square pulses, so there is no decline in signal quality along the strip. Well, that’s the theory. In reality, all sorts of weird failure modes can happen.

Anyway, short conclusion from this testing is: use a TXS-0102 shifter if you’re tight on space and running one or two strips, use a 74HCT245 if you’re not or you are running three to eight strips. The 74HCT245 was the only shifter to give perfect performance, everything else had some kind of problem.

Test results and scope pics

Originally published at Happyinmotion. Please leave any comments there.


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