Jan 19

More toys…

So at the same time that I bought the lidar, I had dropped about a hundred euro on aliexpress on other stuff as well. Most were presents or non-present things for xmas or general stuff like torches, but a few were just for me to play around with on the Raspberry Pis that have been building up around here — an old project came home from work and I realised I had one Raspberry Pi B+, two Zeros and three Zero Ws, one of which I had ordered back in October because I had literally lost one of the two Zeros in my toolbox.

Yes, you can now lose a complete linux computer (which costs a fiver, I’m not rich) in your toolbox. It doesn’t even have to be that full. Welcome to the future. Sorry, we don’t have housing, equality, universal healthcare or even a decent separation between church and state, but we do have a nifty selection of toys, which if you’re having to deal with all the other crap, is probably nothing to sneeze at.

Anyway, I bought a bunch of small things to help with some stuff in the lab (look, it’s a home office that never does office-ing, and it’s got some kit in it that we had in labs in college, so it’s the lab and the shed is the shed, it makes perfect sense to me…). Mostly things like battery holders, alligator clips and test clips, more breadboards and those cool little plug-in power adapters for breadboards, you know the ones? These:

They’re super handy, you can feed them from a USB powerbank or a DC wall wart if you’re feeling brave about earthing, and you get stabilised conditioned power for either a 5V or 3.3V rail thanks to a buck converter and a power switch (slightly more civilised than yanking cords). Neat solution and cheap as chips.

But I was also thinking I could use a slightly beefier PSU to have handy just for things like large LED arrays, and I didn’t want to tie down the adjustable bench supply I have, so I went down a tried and trusted DIY route – just get a cheap as chips PC power supply (the ATX ones go for almost no money and are all rated in the hundreds of watts range with standard voltages and standard connectors) and even bought a readymade PCB with terminals for one.

I also got a variable buck convertor module with display because there are spare leads on that ATX power supply, I might as well feed them into something useful. A bit of work with some wood and acrylic for a case and front panel and I’ll have a nice benchtop tool to work with for half the cost of my current bench power supply, and that was the cheapest Farnell had and it was on sale…

And there was also a megger tester clone because if you’re buying stuff from china that goes near the mains, you want to be able to test it for insulation breakdown and the like.

Oh, not from aliexpress but from dealz (aka poundland) came these:

I know they look cheap (and they are) but they’re bloody handy little gadgets. They’ve made lighting up the lab a lot easier, just stick them up with double-sided tape and the magnet is strong enough to let them act even as downlights:

Along with those, I got a bunch of sensors because wow have the mobile phone and consumer electronics industries gone and made these things cheap. The most expensive one I got was a lightning detector. Anyone remember the StormScope?

Handy little thing that sat in a light airplane’s cockpit (think Cessna 172, not Boeing 767), along with all the extra processing and antenna stuff that was hidden away elsewhere:

And all that gave you an idea of where nearby lightning strikes were so you didn’t fly into thunderstorms.

Now, don’t get me wrong, that stuff was flight-rated and that’s the processor and display as well, but still, to see all that hardware come down to a €20 sensor (including shipping) is something else, especially when that’s the most expensive out of a bunch of these kind of things.

And it’s now plugged into one Raspberry Pi, along with a CO2 sensor and a barometric pressure, temperature and humidity sensor.

And so far, I can only read from two of them, but I’ve not had a lot of free time 😀 As far as I can tell, it’s working fine, I just haven’t stacked up libraries and python runtimes properly just yet. I’ll get to it.

Meanwhile, I have a half-dozen small oled displays originally intended for phones and such and costing no more than €5 for the most expensive, all plugged into another Pi and so far only one turned out to be toast on arrival, but none are as cooperative yet as I’d like (but this is the fun bit).

Oh, and speaking of displays, I seem to have ordered a wheelbarrow of neopixels. They play nicely with Pis as well (er, don’t watch this if you have epilepsy):

I do have a plan for those as well, I just haven’t gotten there yet (I’m wondering if that would work as a lightning detector display, sortof like a DiscoStormScope…)

And then there’s the CO/NO2/H2/NH3/CH4 gas sensor, the airborne particulates sensor, the 3D magnetometer, the other laser rangefinder, the luminosity sensor that works in both visible and UV light, the GPS module and the 3DOF gyro and 3DOF accelerometer which is basically the guts of an INS.

If I ever get some more free time, I now have enough to fill it…

Jan 19

Well that took longer than expected…

So the last time I worked on the desk wasn’t as far back as October, but I didn’t get a chance to write it up (work has been a tad busy and other stuff has also been eating time). But with xmas dinner done, holidays finally kicked in for me and after collapsing for a few fallow days, I got back out to the shed in the last day or so. And managed to avoid breaking my neck on the decking outside the shed as well (some anti-moss napalm has been deployed and I’ll have to repaint that decking with some sort of high-traction paint before any really cold weather hits I think, and possibly drill a few sneaky drainage holes against standing water).

So in previous days, I got the dovetail mortice cut on the sides, using my normal technique for a stopped dado joint, which is to chop a small mortice at the point where the dado stops (so the saw has somewhere to go, though I wonder if a stair saw would solve that). It’s a bit complicated here by the line of the grain not lining up with the dado angle very well, but it wasn’t unmanageable. Then out with the ryoba and very carefully sawing down the edges of the dado. Cutting on the pull here helps a lot, but the japanese saws not really wanting to track on a flat surface doesn’t (western saws I think would be happier as they have thicker plates, but all of mine hate me and won’t work for me at all). So in this case I chopped along the line with a chisel and cut a little knife wall to help guide the saw, then sawed down to depth once the cut was deep enough to let the saw blade track.

With the edges cut down to depth, out comes the chisel and I hog out the bulk of the waste pretty quickly, then switch to the router for the last one or two millimetres of depth. Not the powered one, the one that actually likes me.

Then just repeat that for the other side, being sure to mirror image rather than carbon copy…

This project is right out at the size limit for my shed by the way, if not well past it…

So now I had two dados cut, both of which are as narrow as the minimum width of the dovetail (the bit at the shoulder where the joint is thinnest), so now I had to remove the last bit of waste to form the dovetail. However, after watching some of The Woodwright’s Shop (one of PBS’s gems) I thought I’d just make one side of the dado into a dovetail instead of both. I mean, if it works for Roy

So, I clamp a straightedge in place to both hold the side and give the router something to run against, fit the dovetail bit, don all the PPE, triplecheck where my fingers are, and I fire it up and make the cut.

And it didn’t come out too terribly. I mean, it’s not pretty, but there’s a noticeable lack of severed and mangled body parts in the cut, which I’m a fan of.

Okay, so just repeat for the other side and…

…promptly forget which way the blade is spinning and that this is a mirror not a carbon copy, and that I’m now climb cutting without being ready for it and the fecking thing actually jumps for my face.

Enough with routers, I say. Stupid things. Anyway. It’s done. The joint mortices are cut. And feck setting up a router table to cut the male part of the joint, I’m done with that sodding tool for now. And in fact, that was the last time I got to work in the shed from then until this week, which is when the rest of this all happened.

Right, so I have to cut the edges of this now to let it be driven into the sides with the male part of that dovetail joint, but it also has to protrude out the back far enough to almost reach the wall it’s leaning against. So there was a bit of footering about to get measurements and scribe lines and so on, but finally I got that sorted.

Next up, cutting the dovetail part of the joint. I measured the router bit’s angle, set a bevel to that angle, then planed a scrap offcut from shaping the sides so that its edge matched that angle relative to a face.

And now I had a paring guide for a chisel. Next I pared out the dovetail along the joint.

The back end of the paring guide is up off the bench, with pressure from my index finger holding the angled edge flat against the edge of the desk, which puts the face of the paring guide at the right angle; then I slowly pare away, nibbling at the cut on the second pass, which is when I put a shim under one side of the desk so as to angle the board and thus give me a sliding stopped dovetail joint.

You can see, with the shim under one side (and the other side held down by holdfast), the paring block naturally carves a sliding dovetail shape.

And then I did a test fit and of course it didn’t fit at all 😀 So I trimmed the vertical edge of the dado a few times and eventually got a nice solid fit. And then repeated the process on the other side.

It’s not perfect, I’ve not done this kind of joint before but it works.

Self-supporting! And also way too big for my shed 🙁

Barely fits. Also, the joints are not yet driven all the way home there. It’s a solid fit, but it’s a little tight still (I have yet to finish plane the sides or the desk and I expect that to loosen things a little). And I have to scribe the angles for the top shelf yet, which will be dovetailed in because I hate myself.

Scribing it won’t be a major hassle. Cutting the dovetails while the joints are loose however, isn’t a great idea because the shoulder to shoulder distance varies as the joints get driven home. I might well cut one side’s dovetails, leave the bevel set for the other side and not cut that until closer to final assembly which will be a tad finicky but less so than trying to cut both and then undoing the joints, I suspect. Or maybe I’m wrong about that.

Either way, I suspect the bigger issue is going to be space to work…

And to think I was pondering putting a lathe in here. I mean, I still am (I got a lot of woodworking gift vouchers for The Carpentry Store over the solstice) but I have no idea how I’d get it in there without freeing up a lot of space (and one of those vouchers was for The Timber Yard so there’s even more timber to go in there soon as well).

I guess I need to make more stuff…

Jan 19

Xmas dinner

More cooking this year. Didn’t do the turkey, but did do the beef wellington which went well thanks to cooking the steak sous vide after a quick sear and remembering to wrap it in filo pastry (with mustard on the inside) before wrapping it in puff pastry.

Also did a few sides, like cornbread muffintops and pommes dauphin which were the best (or so I thought) – half mashed potato (made particularly dry) and half choux pastry (also made a little dry), and deep fried for around eleven minutes to make large potato-sized golden brown potato dollops that were crunchier than roast potatoes on the outside and lighter and fluffier than thrice-cooked chips on the inside. Gotta love the French.

And for that teutonic paganism balance to the French, apart from the tree and the lights, I cheated on a yule log recipe, bought two chocolate Swiss rolls and did a bit of decorating.

This worked pretty well, and I used the remainder of the Italian meringue I made the mushrooms with to make a lemon meringue pie, and the remainder of the chocolate ganache that’s coating the yule log went across to top of a pecan pie.

So maybe I need to make less food next year. Because there’s only the seven of us at the table…