Heavy lift

That hoist was a godsend lately. It helped me move bedroom furniture made of carob and also this old rail that weighs a ton.

During that process both of the galvanized channels I used yielded and I was this close to have everything fall down. But I won at the end.

Lifting a wooden rail

It gets better

I spent most of the last weekend studying and a bit sick.

When not reading for the Uni I binge watched a lot of talks from previous editions of the CppCon, because that’s obviously what only a sick person would do.

And after not being on that scene for quite a while I found that, like for some wines, the time made it nicer.

The use of auto variables when iterating containers, lambdas, parallelization and inclusion of atomic operations (albeit I believe they are insufficiently documented and will bite a lot of people) are just some of the things that surprised me in a good way. There’s a host of cool stuff under <algorithm> and the new optimizations (like the ones carried for constexpr ) are incredible.

Coincidentally, Bert Hubert started a series of posts with the good parts of C++ that actually makes me want to code something in it again.

Fixing a metal chair

A while ago we bought a very nice set of chairs with a chromed base and the bog standard pneumatic height adjustment.

After a lot of use a couple of them had the welds on the base break apart. I took one home and after thinking a bit I chose to make a stiffening plate instead of just redoing the missing parts as that area looked very flimsy.

Fixing a metal chair

I traced the outline on some cardboard and then cut a bit of plate with the plasma torch.

Fixing a metal chair: stiffening plate

Some light prep and careful welding made it usable again. I tried first with a small 6013 rod but the arc wandered and blew a hole through the thin base. I had more success with 7018. The welds look horrible but are strong enough, I jumped a couple of times and it didn’t even notice.


Sometimes I use wire cups and wheels on the grinder. Screwing them is easy but the clearance between the guard and the tool makes it very cumbersome to use an ordinary wrench to loosen them. And also they come in different sizes.

So instead of having to carry around two tools that aren’t fit I fashioned one with some flatbar. The welds are pretty enough for a beginner and this application.

After that I gently heated it over the stove to reach a lovely shade of iridescent blue:

Home made grinder wrench, heat treated

Intercom mount

We are installing an intercom system and the front door unit is meant to be mounted in a recess in the wall. But the problem is that that wall is not really suitable for making such a hole.

I cut some strips of flat stock and fashioned a box. It has a couple of tabs to bolt into the wall and another ones threaded to hold the device. This is going to be painted later but I love that blue shading.

Sliding patchbay mount

I’ve been working on and off on this for the last couple of weeks. The space we’ll have on the comms rack to handle the wiring isn’t that great and I saw on a couple of places patchbays that are articulated.

I thought on adding a twist to that and mounting everything on rails. This way I can slide it from behind the rack and then unfold it, gaining access to both sides.

We bought some pre-drilled (but not taped, ugh.) angle with the holes spaced in standard units, that was welded into a fixed frame with a couple of hinges.

This will hang from a small cart with iron wheels that rides on a couple of rails fixed to the walls.

Fixing an inverter welder

Today while working on the rack closet the welder died on me for no apparent reason. But, after power off it made a couple of noises and the fan ran for a moment.

For being a Chinese machine it actually looks quite good and neat on the inside. The boards have conformal coating and just a tad of flux residue on some pads. The only thing out of place was a blob of solder on a header instead of a jumper.

I made a couple of measurements, the high voltage section was fine but the control supply was totally dead, except for a brief moment when turning off the main switch. Traced back from that board until finding a small block with a forward converter (kinda odd, I expected a flyback). The only component with bad readings was the recovery diode. I swapped in an UF4007 and at the next flick it was alive again.

Of all the things that could go wrong with a welder on novice hands this was not expected.

Door frame

The next step in the making of the rack closet is the front door frame. It’ll be screwed to the base and the top support. For that I’ll use some square tubing with a cap and nut welded to each end.

The lines scribed on those pieces look a lot like the iconic map of La Plata.

Each one was beveled and welded in the tubes. I ground the sides flat mostly for looks.

As I still had a while more with sunlight I used the support built earlier to keep them in place and tack everything together. Enough work for a Summer Friday.

Tacking door frame in place

Rack closet

So, after tearing down part of that wall we needed a safe way to store the equipment. It also has to be a bit above floor level, as we plan on making a small stage.

For the base I used some C channel iron. Parts of it were a bit mangled, so I made a makeshift tool with an hydraulic jack to spread its sides and have a good fit.

The top is simpler, it just needs to hold the vertical struts in place and the light fixture.

Then I centered it on the base and proceeded to punch and drill the holes to locate the rest of the structure:

Rack Closet: making the base

Reduce, Reuse Recycle summary December 2017 – January 2018

(Sounds nicer than saying dumpster diving eh?)

We can learn a lot about a society just from looking what we throw away (see Garbology).

When I lived in Berisso it was really odd to see on the curb something that worked or was fixable.

Here in La Plata and without even trying I stumble upon stuff that is just a little bit broken if not working (albeit a tad old).

This last two months among other things I picked up with my bike basket:

  • A vacuum cleaner, complete with hoses. Only needed a carbon brush replacement.
  • Home audio amplifier. The cd tray is stuck but we feed it from the line in. A bit heavy but very nice sound.
  • Mantle top fan. Works fine as a fan but the pivoting mechanism is acting up. Just needed a thorough cleaning.
  • Leather briefcase. Sold in less than a day as a theater prop.
  • Wooden wine rack. Works fine for other beverages too.

This is not exactly dumpster diving but I also helped the widow of a neighbor silent key to clean up his shop.
Out of the deal I got:

  • Two 100Mbps rackable switches. They work but at that speed I only want them for the chassis and supplies
  • An antique lamp. Already restoring it.
  • A Commodore 1541 dirve and some original CompuServe disks. On their way to a museum.
  • A very old (when telegraphs were the norm) glass insulator and threaded pole made of hardwood. Has the right volume to make a shot glass.
  • A modern medium voltage insulator. It’s quite heavy but in nice condition. I’ll probably make a lamp out of it.
  • Lots of heatsinks and coolers.
  • Old cans of candy and medicines. They don’t have a high monetary value but are collectible and can be traded for something else.

Making space

We decided to tear down part of the wall that divided the old studio from the control room in order to have a bigger space.

Before it looked like this:

And after a bit of effort it became this:


After making a lot of room on the shed I still had this feeling that the space was under utilized and I started to think of a small raised platform of sorts.

As luck would have it I had some leftovers of C channel from another project and they are perfect to make a frame and put some osb boards.

They are a bit cumbersome to handle by myself so I built a couple of hoists with some sheaves and scraps.

This proved to be extremely useful not only to lift but also to keep everything in place when drilling the wall.

It took a couple of days but I finally managed to make it with a bit of help from my dad.

Tooling up

Since I moved back to my childhood neighborhood I reconnected with a lot of people that were part of my developing years and imprinted many memories that I still recall fondly to this day.

One of them is a very nice old man, a bit younger than what my grandfather would be were he be still alive. From time to time I help him with the daily errands and every other week we share a simple lunch. He used to run a hardware store that marveled me every time I went (when I was a child I could be impressed with simple things. Thankfully, now I still do).

Nowadays the store is run by his sons. He comes anyways, sits on a corner drinking mate and welcomes the patrons. Besides knowing almost everyone around he’s also versed in almost any trade I can think of and that skill is quite useful, as many times people come without knowing what they need or how to fix something.

I visited him for new year’s eve and between a glass of wine he said come to the shop once the holiday craze fades, I have something for you.

A couple of days later I go to the store and without a word he carries me to the back into a room I never visited before.

This are all the returned items that we can not send for repair. Some customers are worth keeping and so we just give them a new machine instead of washing our hands because the manufacturer would not take them. Pick what you want, we’ll talk business later .

I got this out of the deal at a very discounted price:

  • A combo tig/stick welder plus plasma cutting with all the standard accessories and an auto darkening mask.
  • A drill press.
  • A miter saw.
  • Small air compressor.

Besides that he sold me safety gear, consumables and a couple of other things like magnetic squares and pressure clamps, air hoses with quick disconnects, a paint gun and a spraying one.

You don’t look at a gifted horse in the mouth but given that these were rejects I had to.

The welder was only banged a couple of times on one side and had some loose connectors. After fixing that it worked flawlessly. It came with all the torches, water tramp and pressure regulator and spares.

The compressor is way loud and one of the connections between the reservoir tanks and the regulator has a leak, I can see oil (or moisture?) bubbling when it’s running. It’s not a big deal and while the fix is easy it involves fumbling with very delicate tubing and I know from experience that a bit too much of torque can easily wreck them. Also it’s not very ergonomic, the handle has sharp edges and if I’m supposed to use it to move it around I have to crouch. As it is not very heavy I just lift it whenever I need to move.

The drill had less than the barely minimum grease on the table lift column (none) but surprisingly the chuck turned smoothly after loosening the belts. However the quill felt strange, like it was scratching something inside, and also the spring was harder than I’d like to. To dismantle it only needed a single screw to be removed and when it was out I swept the innards with a cloth and it came back with what looked like metal (or very thick paint) flakes. After making sure that none of that remained I applied a very generous amount of grease and put it back together.

Runs quite fine but the table has a bit of flex, nothing that a brace wouldn’t fix.

I don’t know what’s wrong with the miter saw. The stock abrasive disk is very soft and flexes, so making square cuts is a difficult task, and it really needs to be bolted on something hard, otherwise the frame tends to distort when applying pressure to the vise (just the necessary to keep things in place, seems like a production defect).

All of this came just in time, as I’m doing a couple of renovations on my parent’s house. (The neighbors are not exactly thrilled, as all of these tools make quite a bit of noise).

Low level fun.

As a wise man said, “low level is easy”.

There aren’t that many things below that can break except for hardware (and compiler!) bugs, they are becoming increasingly common but still the level of pressure and control to keep quality up on processors are orders of magnitude greater than those on the stacks above the OS.

A minor update of Ruby broke everything? The layout is totally wrong when a browser locale is set to Spanish but no in English? Who’s to blame for that? Even if we have most of the sources fixing the problem for everyone but ourselves isn’t that easy.

The other Monday I went to the Uni to take an exam on digital circuits (graded with 9/10) and oh boy, programming in assembler again was refreshing.

The tooling is just as awful as the last time I took that course (not as bad as the first versions of mplab but the assembler is still dumb when it comes to parsing spaces and the integrated editor is notepad in disguise) but the difference is that now they allowed us to use our own notebooks. The only saving grace is that the assembler, debugger and simulator are different executables, they accept a sane set of command line parameters and they run fine under wine.

So I was able to use vim and a simple makefile to streamline the process and finish in almost no time. Sadly the bar to pass has declined a lot in the last years.