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Learning to cut dovetail joints

I made a couple of New Year Resolutions this year, which is unusual for me. Although, I think the last two I probably went for were ‘parent better’ and ‘drink less’.

But this year I have two SMART (specific, measurable, achievable, realistic timely) goals; raise a pig for the table and learn how to hand cut dovetail joints.

The pigs will probably live through this year, as we’re planning on housing some on Cansdell farm later in September or so, but I am putting a cross through “learn to cut dovetails”. This post will talk about my learning process.

The dovetail joint has seemed like witch-craft to me for years. My Dad was a great woodworker, but even more so he instilled a wonder in other people’s work. We would look at furniture and he would point out bits that were hard or clever. Dovetails always seemed like some sort of threshold to me, the point you cross between handy-person and woodworker. And they are the first thing to disappear when furniture gets cut by machine. I like IKEA, but it will be a long time before they release hand-cut, dovetailed kitchen drawers.

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I had dabbled with the idea for a while, even going as far as buying a back-saw (tenon saw) and a sharpening stone for my chisels. But the thing that pushed me over from thinker to doer was a bundle of woodworking magazines that arrived in the post, the end of Dad’s subscription after he died 18 months or so ago. In a flurry of nostalgia and casting about for a project I decided to learn these things once and for all.

I think this was part of the eventual success; I wasn’t trying to make something, I wanted to learn a new skill. Learn it so I could do it in my sleep, and then dovetail every piece of wood in the house. This meant there was no time pressure, no need for them to be good from the outset, I could focus on the process, the continuous marginal improvement which comes from learning a new skill.

The tools I used throughout were pretty simple; a cheap tenon saw, a cheap chisel, a good wooden mallet, a razor blade and my bench and vice.

I started by watching some videos. This was the best one to get me moving:

Seeing someone do them so quickly made it much more accessible. About 3 minutes and he has a corner done! Very neatly too I might add. Armed with this basic technique I went and cut some joints.

The first 4 were pretty bad, but there were little improvements each time. Better chisel technique, straighter sawing, more accurate marking. Here are the first 5; number two exploded during assembly.

2014-02-02 19.36.00During this period I read a bit of dovetail theory and history, which helped with my confidence and ability to just give it a go. Dovetails were developed as a fast and dirty way to join two boards. You cut the tails by hand. It virtually doesn’t matter what they look like, as long as they are perpendicular to the plane of the face. Then mark the pins off those tails, and cut them exactly. So the crux is that marking, then cutting operation, and most of the improvements in the second half of the test series were found here.

This video helped a lot as well …particularly because of the jig he uses. I lusted after one for a while, before realising I could make one myself pretty easily. I’ll write a post on that separately, but here is the jig and the first joint I cut using it. A marked improvement.

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The jig sorted out my sawing technique, making much straighter, sharper lines. Another marginal improvement came from clamping the jig rather than holding it.

The last piece in the puzzle was my chisel technique. For me, the most difficult part is neatly removing the waste from between the tails/pins. I was using 19mm board for most of my practice, which meant I needed to do more chiseling than in the videos, which were typically using 10mm and quite soft boards. So I watched some videos on sharpening chisels first, then some different techniques. I settled on ‘pairing’ in the end, where a vertical cut is made with the chisel on the line, then the fibres are dug out sideways until you get to the bottom of the initial cut. Then repeat.

2014-02-02 19.36.10By number 9 I was ready to make something. I bought a piece of FSC Tassie Oak from Bunnings and set to work. A week later and I have my first box.

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It looks much nicer than I expected, and sturdy enough to hold anything that will fit in it. Perhaps not a dynamic toddler. I am happy with the product, but more than anything I am happy that I know dovetails now. Even during the box I ironed out a few little technical problems and picked up a few pointers for next time.

2014-01-30 08.26.40I am not using a pencil for marking ever again. Before gluing up there was an obvious difference between the first and second pair of joins, traced back to pencil marking. The pins and tails need to match really closely, each side very close to, but not crossing an imaginary line. So you mark the line as sharply as possible, then cut up to, but not over the line. Under cutting is better as you can shave off a little during assembly.

2014-01-28 20.12.20Now that I know I just want to spend all of my time cutting them. What else could I dovetail? Where can I get more wood? I’m really interested in ways of upcycling wooden pallets at the moment, particularly the soft-wood ones which are commonly discarded. At least there are plenty around to practice on. I’ll let you know how I go.


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A question for AGW “skeptics”

For better or worse, I have spent quite a bit of time arguing with “humans are causing global warming and it’s a bad thing” deniers/skeptics on the internet. I don’t expect I will ever change their minds, in fact I am increasingly sure that I can’t change their minds, but it’s interesting to have a discussion and see where their objections lie. Then I know more for the next one I meet, and I might be able to convince a couple more observers, who I think are the main candidates for having their minds changed.

For the record, I accept that human emissions of CO2 are changing the climate and that this is a bad thing. I don’t ‘believe’ this. You don’t need to believe in things that can be measured.

Something interesting has emerged from these discussions: I think I have found the denier’s kyptonite.

In all of these discussions, and I don’t think I’m exaggerating to suggest there have been more than a hundred, none of them have even offered a sliver of an answer to the following question:

If the globe was warming due to human actions, what would evidence of it look like?

No one has ever attempted to answer this question. Some have said “well I can tell you what it doesn’t look like” and “the world hasn’t warmed in 15 years” but never has there been an honest attempt to describe something which constitutes evidence that humans are causing the climate to change.

It is incredible that people so well versed in science that they can disregard the vast bulk of scientific work on a topic can’t answer this question. They can describe in great detail why any given piece of evidence isn’t evidence of climate change, but not what would be. This is the very essence of both science and skepticism; once you know a theory you know what will break it and you look for it, constantly.

I am not overly surprised, the skeptics I have debated don’t usually answer any questions at all. I suspect this is because on some level they know that once they offer a position on something they can be disproven, and that’s dangerous territory. Much better to make wild accusations and ask questions, and then you can never be wrong.

I’m not sure what to do with this information; it’s not going to change the politics or the difficulty of achieving global agreement on emissions limits. But I think it indicates a strategy. What if rather than people like Andrew Bolt getting away with nonsense such as “the world hasn’t warmed in 15 years” someone replied with “great point Andrew. You seem to know an awful lot about global warming, what do you think evidence supporting the theory would look like if it were occurring?”

Let’s start asking, not answering, questions from the skeptics among us. They know SO MUCH, and we should try and learn from them.

Assuming of course they have anything to offer.


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TED Talk – A low energy use life is glorious.

I did a TEDx Talk in Canberra recently. Here’s the video:

In this talk I wanted to get people excited about an energy efficient lifestyle. Rather than the Earth Hour view that to save the planet we need to go without I think an energy efficient lifestyle is actually pretty nice and this talk focuses on some of the co-benefits that come with energy efficiency, using some examples from my industrial career.

Let me know what you think.


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The energy efficient house – Canberra retrofit

We have just sold our first house, a little brick house in Canberra’s inner north, typically called a “Govie” by the locals. We were there for 4-years and during that time we changed the Energy Efficiency Rating (EER) from 0 to 4. I’ve been promising for a while to write this up, so here it is. What we did, and what we should have done.

The House

The front wall, winter sun behind the camera.

Three bedroom (more like 2.4) brick-veneer house. Single brick on the outside with timber stud walls and plasterboard. Suspended timber floor without carpet. Timber framed gable roof with concrete roof tiles. Windows are all single pane in timber frames. The front of the house has the most glass and faces about NNW. The house was built in the late 60s

We didn’t get seriously into the energy efficiency modifications until about 2 years in. We had bigger fish to fry before that, like re-doing the bathroom, which had some excellent examples of early 70s asbestos.

Ceiling Insulation

We received Pink Batts money from Kevin Rudd and got what we could for free and felt pretty good about it. There was essentially nothing in there before then and we added R4 batts, which cost about $800 in 2010.

We should have spent a little bit more and gone for R5 or even R6. Canberra is a properly cold climate, so it’s worth significantly insulating the ceiling. Much of the cost of paying someone to install insulation is just showing up, so spending more on the materials is better value than upgrading it later. This guide from the Victorian Government gives the range of values for the different climates in Australia.

Draft Sealing

This was really worth doing in this house, as the main form of heating was ducted gas. This has vents in each room which blow hot air, and a large central vent that sucks air out of the house. Because the friction in the room vents is higher than the central vent the pressure inside the house is lowered slightly and cold air from outside comes in through every single little hole and crack.

The range-hood was the worst. It had a pipe straight through the wall and a broken flapped exhaust port. I cut a piece of neoprene foam (an old hiking mat) that fit the hole exactly, stuffed newspaper in from outside, then put the cap on. We just decided not to use the range-hood in winter.

I sealed the external door frames with these special squishy tapes you get in hardware stores, and put weather strips on the bottom. This can be a bit of a fiddly job and makes your doors work badly if you’re not careful. Buy a range of thicknesses and have a good look at where the door sits (or more importantly doesn’t sit) against the door jamb. It will probably take some fiddling to get the latch-tongue to go into the strike plate when you’re done too. I used a little file to open the strike plate on a few doors.

I did the same to all the internal doors as well. This means that you can use the room to insulate the hall against the outside of the house, and again because of the gas heater suck it was another way of slowing air movement.

Window Treatments

We didn’t have a lot of money for this step, and were terrified by the idea of making curtains. So we bought blockout roller blinds, which were really good at keeping the heat out, and moderately good at keeping it in. We also used semi-opaque honeycomb blinds in the big window in the front room, which we loved. They have noticeable thermal affect, and the good ones will supply a tested R-value. The slight transparency meant it let light in while they were closed, which was nice, but mostly for privacy.

Outside we put roller blinds on most of the windows. The kitchen window got hot early sun in summer at an awkward angle, then the front of the house baked in the afternoon. These blinds were great actually, and made the house much cooler in summer.

If I had my time again I would have put the external blinds on for the first summer.

Inside, I would get high-quality honeycomb blinds made to fit snuggly inside the window frame (actually called the “reveal”, the wooden frame that engages the window with the house frame). This would probably be a bit expensive, in which case I’d buy a good sewing machine and go for it. But honeycombs would be my first choice.

Wall insulation

This is another thing I wish I had known about earlier; until we’d done almost everything else I didn’t think this was possible. Turns out I was very wrong.

The brick veneer of a typical Govie creates a great pocket of air between the plaster board and the bricks. There are now machines and insulation products designed to exploit this and they can pump insulation in. It cost us about $2k and after the first round of draft sealing probably made the single most noticeable difference. Strongly recommend this step, particularly if you have the same construction technique.


I probably should have put this at the top of the page as many readers will be interested in it, but it should not be your first priority when looking for the most effective projects.

We spent at least $15k on ours, replacing every single piece of glass in the house, in 21 separate apertures. The cost affect is actually hard to judge for an individual, as it looks like we might have added that much to the value of the house at sale. But for the house, the payback period is in the order of 30 years.

However, in terms of niceness, the windows were hard to beat. The originals were very tired, push-out awning windows, that leaked in a way I couldn’t fix without gluing them shut, which I did in a few cases. Rather than hinging at the top they hinged off a brass bar in the middle, and the top slid down. Then where the bar folds into the frame there it a gap that you can actually see through. They were awful to use, which involved opening the flyscreen like a door, then diving out the window to push it far enough to sit still. Terrible things.

For all 5 of those we went for aluminium framed “sash” windows; two panes that slide up and down past each other. The first thought behind this was to open top-down in the afternoons to eject heat, which worked really well. Every day once the outside temp was less than the inside temp we opened all the blinds and all the windows, which made a difference quickly. The aluminium frames are not ideal for thermal performance, but at that time we didn’t have much choice in suppliers. This guy got the job because he was the only one who would show up and quote. UPVC and timber are becoming more commonly available now and they work much better than aluminium.

On the north wall we used a laminated and coated glass called ComfortPlus, made by CSR. It’s not quite as good thermally as double-glazing, but we used it for a number of other reasons. First it’s a toughened glass, which we wanted for the front room which has glass at ground level, and we had a toddler whose favourite toy was a hammer. It also blocks UV light, which means your furniture and floor doesn’t fade and your baby doesn’t get sunburnt lying nude in the sun. Lastly it blocks IR light as well, which slows the heat transfer into the house in summer.

The south is all double-glazed.

Southern wall of the house, halfway through deck construction, with new windows.

If I had my time again I would try pretty hard to get double glazed windows, with toughened and coated glass, in UPVC frames. A bit of a scout around suggests there are more suppliers operating now than when we were shopping, and a lot more choice.

Hot Water

We didn’t touch, but should have tried harder. We had a gas storage hot water system, which doesn’t lend itself well to solar addition. The problem might have been that I just didn’t speak to anyone imaginative enough, as I have since found solutions to that problem. Evacuated tubes work really well in Canberra and have been cost effective for years.

The idea

As I’ve mentioned elsewhere, I would rather you don’t just make energy efficiency decisions on cost. If possible, consider niceness. You are pursuing comfort, rather than spending the least amount possible on energy. Just pursuing costs can lead to some perverse and unpleasant outcomes, like living in a north facing, perfectly sealed Esky.

Hold in your thoughts a house that keeps the heat where you want it, but is also well ventilated when you want it, with easy to operate equipment made of durable materials.

I’ve written at The Conversation about the fundamentals to consider when launching into something like this, followed by a period of thinking and observing. Where does the sun fall in summer and winter? Any big deciduous trees that will block sun in summer and allow it in winter? Where does the air go that I don’t want it to? Which rooms do we use and when?

And this is the fun part. Making a house run efficiently is a dynamic and complex problem. As the seasons and usage patterns change, so do the most efficient choices. But I encourage you to give it a go, it’s surprising how much difference a few simple changes can make to your comfort.

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Interventionist Conservation.

My environmental ethics can be best summed up as Conservationist. I think ecosystems run best without human interaction and that in places that we have broken them, by introducing weeds, ferals or poisons we should take steps to fix that. Native species should be vigorously protected and degraded, wild places rehabilitated.

So in the first instance I want to see what little wilderness we have left, protected. I strongly support the creation of national parks and am pretty hardline about what activities should be allowed there; I am actually pretty comfortable with bush walker-only rules for a lot of national parks. I also think we should take just about every action possible to ensure areas we have inhabited don’t further degrade the other bits. That means we minimise pollution from powerstations and the like, and ensure our waste is treated to very high standards.

All of that is easy for most people, who would rightly consider it basic environmental protection.

But what about the intervention bits? How far am I prepared to go?

Almost without dispute, humans have done more damage to the natural operation of ecosystems than any other factor. Do I want to run them off the land? No, not really. I acknowledge that we need to grow food and live in shelters. But extending the idea above, when pursuing these activities we need to minimise the damage caused on and off-site. So I am a strong advocate for free-range farming, conservation tilling, water conservation and organic agriculture in general. I also think we should make our buildings as efficient as we can, using materials that can be re-used or benignly sourced. Would I support policies to reduce population growth? Probably not, but I think we could do a better job of educating people about how their choices make impacts across the biological sphere.

The hardest part of this for a lot of people is where a generally well-intentioned animal welfare ethic tangles with conservationism. It is here I have had many passionate and sometimes emotional discussions with people, mostly on Twitter, and it’s a hard point to articulate in so few characters.

I agree unquestionably that we shouldn’t intentionally cause suffering to animals, either wild or domestic. But what about the places where one animal is causing harm to others? Foxes and cats have probably made species extinct in Australia, maybe even as many as a dozen. Do we just let them go?

If it’s a “natural” (and here natural means “the dynamic equilibrium achieved through thousands of years of evolution”) predator to prey relationship, sorry to say it but you’ll have to fend for yourself. I am not about to start hunting Lions and lecturing them on the ethics of Springbok conservation.

The big problems come when a predator, or just a destructive species, sidesteps the normally cautious approach of evolution and starts fiddling with other ecosystems. Many would argue this is what humans have done in most areas.

Most Australians would agree that when the species is a cane toad the solution is obvious; kill them without prejudice. But for reasons I can understand on some level, this gets harder for people as the species in question gets bigger.

I am completely in favour of killing foxes, cats, goats and horses in the wild in Australia. I want it done quickly and humanely, but there is no question in my mind whether we should intervene in these situations. Doing nothing here equates to killing native species and in some cases that’s going to make them extinct. Foxes and cats are incredibly good at killing small mammals and birds. Have a look at the Wikipedia list of mammals made extinct in Australia and wonder how many of those died in the jaws of a fox or someone’s house cat.

Goats and brumbies are a little more subtle, but the outcome is the same. Goats change the botany around them, by transporting weed seeds, eating shrubs and ringbarking trees. They soil waterways and cause soil erosion. They simply must go.

Similarly brumbies, for all their majesty and romance in Australian folk-lore, really have to be removed from the Alpine National Park and surrounding areas. They’re a big, heavy, hard footed animal and cause incredible damage in the wet areas of the mountains. Imagine a fern filled valley with wet mossy pools and a slowly wandering stream. Then imagine what it looks like after a dozen horses each weighing a few hundred kilos wanders through looking for forage and water. There’s a real chance that brumbies could eliminate some frog species, like the threatened Corroboree Frog. Not through predation, but just by wrecking their habitat.

So I accept the commonly raised objection that “it’s not their fault”, but this is one of those times when doing nothing is as bad as doing something. Sitting on one’s hands and letting them carry on killing things might be okay for your ethics, but not mine. Conscious, considered actions are what’s going to save our remaining native species and I am quite convinced that the longer we wait the worse the impacts of cats and foxes in particular are going to be. The exact methods are for someone else to determine, but I strongly support the principle of removing feral species.

For this to work, I’m really only talking about species removal, not so much introduction. As a general rule I’d say that the shorter time a species has been present in a new ecosystem, the easier the decision to remove them. Common Mynahs (often called, incorrectly Indian Mynahs) in the suburbs? No worries, they’ve been here 50 years, don’t belong, let’s get rid of them. But what about some of the weird middle ranges? Dingos have been in Australia for 6-10,ooo years, a short time in evolutionary terms. Should they be here? I don’t know to be honest, but we’ve got bigger problems than that to consider.

Extending these ideas into areas that some environmentalists have difficulty with, I also support banding birds to gather data on their populations and habits, fencing off populations of endangered species like the Northern Hairy-Nosed Wombat and the Bilby, and introduction of biological control measures (some of them) like calcivirus to reduce rabbit numbers.

I concede that this is a complex problem, and making the decision to kill something should not be taken lightly. Ever. But this is not a scenario where there can be no killing. Either we remove the pests or they remove our natives. And given all of the above, I’m very much on the side of removing the pests.

Would love to talk about this further in the comments.

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My Now Hear This Story

Mostly just recording this for my own records, but here is a video of me telling a story recently

It was told for a night run by Melanie Tait, ABC local presenter. The night is called Now Hear This and runs occasionally. Their next one is up at Mt Stromlo and will be stories from the 2002 Canberra fires.

It was a fun night, in a terrific setting. I might try this caper again. I wonder if the audience is ready for some birdwatching stories?

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