Light sabre

Ever been sunburned? Gone to bed with that awful, sweaty, stinging feeling of hot regret? Had little blisters form then pop? We pretty much all have haven’t we. Stupid bastards that we are! “Stupid” because that ol’ friend of ours, our nearest star, our planet’s parent and orbital centre, The Sun, puts out a lot of energy. Just how much; well obviously enough to broil your shoulders at some point!

As this picture clearly shows, you can work out the energy received at any given point using this simple formula:

\overline{Q}^{\mathrm{day}}, the theoretical daily-average insolation at the top of the atmosphere, where θ is the polar angle of the Earth’s orbit, and θ = 0 at the vernal equinox, and θ = 90° at the summer solstice; φ is the latitude of the Earth. The calculation assumed conditions appropriate for 2000 A.D.: a solar constant of S0 = 1367 W m−2, obliquity of ε = 23.4398°, longitude of perihelion of ϖ = 282.895°, eccentricity e = 0.016704. Contour labels (green) are in units of W m−2.”

Got that? Clearly though this formula doesn’t account for the various ways that the Earth’s atmosphere absorbs and scatters the energy as it travels from the outer edge of the atmosphere to ground level. That varies depending on cloud cover and other suspended moisture, suspended particulates, vegetation and so on. So lets just sum it all up and say that the sun puts out a lot of energy and on a hot, clear day you could fry an egg very, very quickly using just the sun’s heat.

Which brings us to this little conundrum; what do you do with an old satellite (internet) dish that has been superseded with a newer, faster model?

IMG_0623Do you;

  1. Give it to the dish-installer man to take away and dispose of?
  2. Turn it into a very large birdbath?
  3. Leave it forever behind the garage until the Missus yells “Clean that shitpile up!”
  4. Use it to make mischief (in a fun, harmless way of course)?

Guess which numbered box the money is in….you betcha….Number 4!

There are quite a few YouTube videos of people making reflector dishes out of old sat’ dishes. Many of them use the little, square mirrors, like off a disco mirror ball. All I can say is that they must be richer than me, or at least more willing to throw money at a simple, fun project. At the cheapest price I could find those mirror squares for sale the total cost for enough of them would have been $400-$500. No way José!!

Reflective Mylar film is another matter – a roll of that comes in about $40-$50. The overall reflective properties probably aren’t quite as good as a set of glass mirrors (Mylar film comes in at about 92-97% reflectivity, not too different than mirrors as the actual reflective material in a mirror is basically the same stuff; however the Mylar film is impossible to adhere to the dish without some imperfections resulting, such as ripples, bubbles and some areas of glue overspray) and of course the film won’t be weatherproof so the dish will have to be stored indoors. However these cons just pale into insignificance against the cost savings.

The film was cut into (roughly) triangular shapes to allow us to better shape it into the dish. To glue the film to the dish we used a spray adhesive, masking off each previously glued section to prevent (OK…minimise) overspray.

Here is the completed dish, mounted on the post, leg spars and roof brackets that were intended to actually put the original dish on a roof, and are here slightly modified to provide a stable, free-standing base.

IMG_0635It all looks very innocent. Looks can however be deceiving…

More mayhem….errrr….I mean “Scientific Experiments of an Educational Nature” videos to come. The video above was our first “experiment” which was performed at around 2:30pm mid September. Can’t wait for mid-Summer at between 11am and 1pm (solar time).

Warning – try this at home.

The Coffee Table Book (Addendum)

Vermont is a bloody nice place. Nice people. Nice coffee. Nice environment. The ONLY state in the USA which has a state capital (Montpelier) which does not have a McDonalds outlet in town. I mean…how good is THAT! I particularly recommend the Rivendell Book shop there as being a very cool little bookshop selling a mix of new and second hand titles, which also features highly knowledgeable staff who can find a second hand copy of Finnegans Wake in an instant, without resorting to looking on the computer to see if they have it in stock and if so where in the shop it might be. The shop also has a very happy looking turtle in a large tank in the rear children’s book room. You don’t get that buying books through Amazon.com.

Vermont was also the birthplace of Edward John Phelps.

Edward was a man of excellent whiskers, crinkly laugh lines around his eyes, and a habit of quoting other, similarly whiskered men, for example a certain William Connor Magee.

Now ol’ Billy Magee actually lived during the early years of photography, albeit he died well before every man and his monkey was busy snapping selfies every second of the day. Despite Billy and photography sharing their timelines all we have as a visual reminder of little Billy is this:

I think we can all agree that either Billy was, ahem…not everyone’s idea of a “Babaliscious Stud”. Or perhaps that this is not exactly the best drawing in the world. Still…now I know who inspired this character:

Despite appearances ol’ Billy Magee was no fool, and he is famous for saying “The man who makes no mistakes does not usually make anything”; exactly the words that Edward would quote some years later.

And so it is that via a circuitous route we come to the postmortem of the coffee table construction, for it certainly was not without the making of mistakes.

To be fair, the only “formal” learning I have received concerning woodwork came in the form of a woodworking class I took in Year 9 or year 10 in High School, and I can’t say I was “Top of the class”. Still…life I think can make one more practical as time goes by, and so those long ago learned basics are perhaps today augmented by a little more common sense and a set of basic tools with which practice has made me familiar, plus some feeling of security that comes from the knowledge that any mistakes made are mine alone and won’t be counting toward a dreaded school report at end of term.

Things I would do differently next time:

  • Keep a wider separation between random bits of cloth and electric planers.
  • Even when knowing which way I wanted the legs glued, slap myself a few times before drilling and gluing them together.
  • Work out some way of rigging up a planing jig (without having to buy one) so that I could have finished the timbers for the top slab to D.A.R. state ie. planed to squared dimensions. The individual strips within the edge-dowelled slab don’t quite come together in some places as the sides were planed to eye-sight not in a jig. Overall this looks OK as the finished piece has a deliberately “organic” shape anyway, but having the timbers D.A.R. would have been nice.
  • Cutting to length braces that match the distances between the leg cuts on the bottom shelf, allowing the legs and shelf to be (dry) clamped to the exact dimensions, using the braces to keep the correct distances between the leg pairs before drilling the dowel holes in the tops of the legs and then in the top slab. Despite the best care somehow the legs ended up moving out a little during this step, thus the cut-outs in the bottom shelf each have about a 1.5mm gap instead of each leg being tight into its cut-out.

That said, I am happy with the outcome. It is nice to put something down on that table and know that it is a product of my own effort, and not something that has been spat out at volume from some distant, anonymous factory. It is also nice to know that this piece of furniture has not required the felling of some new forest in order to make it, as it is (mostly) a product of re-using old timbers. Finally, it is good to take some old piece of timber and turn it into something useful.

Thus life’s circle turns and what was ageing and passed it’s first purpose has become something new.

 

The Coffee Table Book (Part 5)

Time to dust off the tools and replace those buggered legs.

IMG_0598 copyHere are the two, glued and finish-sanded sets of legs. Sadly there were no more “nice old bolt holes” to be had, but each leg features a couple of nail holes, from which the nails have been pulled (well….”mostly pulled” as a few snapped off despite the best of care).

IMG_0485Next step is to trim a slab of White Cedar that was gifted to me a number of years back, and which will form the bottom shelf of the table – as well as doubling as lower bracing between the leg-sets.

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After cutting the cedar slab has then been sanded with 80, 120, 240 and 280 grade paper. There was quite a bit of saw blade chatter marking on the board, especially near the larger of the two circles in the grain (where a branch would have originally grown). To completely eliminate these would have required taking about 2mm off which was impractical for a number of reasons. Hence the worst of the chatter has been sanded out before moving on to the finishing sanding. The end result is smooth, if a little ripply.

Here are all the pieces waiting for final assembly – pretty much the last time this is going to look like a pile of parts.

IMG_0598Here is the dry assemble – prior to drilling out the dowel holes in the top slab and the bottom shelf. Basically everything is just sitting, balanced on top of everything else at the moment.

And all clamped up for the final gluing…

After about an hour or so on went the first coat of linseed oil; everywhere except where the clamps and the glue were, because by this stage I just couldn’t wait to see what the grain was going to come up like…

Time to put it all away and let the final glue cure overnight!

<-Go to Part 4 …. Go to Part 6->

 

The Coffee Table Book (Part 4)

I admit it…I’ve been sulking for a little while. I’d thrown my safety goggles out of the pram. Downed tools. Generally turned my back on the Coffee Table project. You see….someone had been twisting my leg!

A while back I did a “finish sand” over all the surfaces of the first set of legs, dowelled them up, and braced and glued them. Here they are;

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One of the legs had a lovely, feature “bolt hole” for which this length of timber had been selected. All that remained to be done with this leg set was to give it a final finish-sand, especially to remove excess glue around the joints. All good!

Except….I’d put the legs on the wrong way! As you may see in the “middle” picture the leg timbers are rectangular, not square. In this leg-set I dowelled the crossbeam into the short side of the legs, not the wide side. This error is more than simply one with aesthetic implications, as it makes the overall leg set too wide for the table top.

Bugger-ation!!

No way to redeem this now – it just goes into the newly created “Collection of very nice H-shaped timber pieces that may one day be useful” pile. I’m rather hoping to not add too much more to that collection!

Oh well….after a little sulk it’s time to cut two more legs and start again!

<-Go to Part 3a …. Go to Part 5->