Category: Metalworking

The family mainframe (by )

I'm in the process of consolidation the home fileserver and the public Internet server - currently two separate bits of hardware - into a single physical device, virtualised to support multiple indepedent machine images. Having a single family mainframe will simplify the management of the complex web of computers and services that support our digital life.

For various reasons, the best place to build such a thing is at the office end of my workshop. Even though it's at the "clean" end, this is still a room that is prone to having fine conductive dust in the air, varying humidity and temperature, and (heaven forbid) a leaking roof. Also, I want a case with extensive room for upgrades, and which makes it easy to replace parts. Having used 1U rack-mounting servers for quite some time, I am sick of highly compact servers that are difficult to work with, requiring extensive dismantling to get to parts.

Clearly, I needed a rather special chassis for this new family mainframe, so I bought a load of steel, picked up my tools, and got to work. I've been working on this for months; I initially cut up the metal at home, then visited a friend's workshop to borrow his pneumatic rivet gun and his MIG welder. Since obtaining my own TIG welder, I've been able to continue at home.

The chassis is nearly structurally complete; this weekend, I've been attaching mounting brackets inside it for everything to attach. All that remains is to finish welding the upper panel on, then the whole thing can be cleaned and galvanised, and the exterior painted. Then I can fix it to the wall and start fitting the electronics and electrical systems!

The first thing I did this weekend was to fit mounting brackets for the processor frame. This is taken from a standard ATX case, and is the base plate with standoffs to mount the motherboard, the frame to attach expansion cards to, and the frame to hold the PSU. This is screwed into the chassis, so that I can use an existing frame (rather than having to make one myself), and so I can replace it if needed. The frame is held in place by two locating pins that fit into holes in it, and then two screws through the upper-left corner (I drilled and tapped holes in the top left bracket), and a little spacer at the top right to stop it from flexing:

Processor frame mounting brackets

With the frame in place, it looks like this:

Processor frame in place

Next came the expansion frames. I may need to add additional hardware inside the chassis in future, but once it's holding a running server and painted and bolted to the wall, I can't really take it down to weld additional brackets into. So I cut off one-inch lengths of square tube, drilled and tapped a hole in the centre of one side, and welded them to the inside of the chassis. I drilled holes in the ends of strips of steel, so they screw into the pairs of brackets, creating a metal strap that can be removed, things mounted onto (via welding etc), and then screwed back into place, without causing major disruption. There are two - one beneath the process frame, above where the UPS will go; and another right at the top, above the environment management system.

Here's the upper one:

Upper expansion frame

And here's the lower one:

Lower expansion frame

The welds were quite difficult, as I had to reach right down into a corner of the chassis. As such, they were either OK or awful, depending on whether I had to use my right (dominant) or left hand:

Lower expansion frame (left hand bracket)Lower expansion frame (right hand bracket)

I also cut and drilled some mounting flanges, which will be what are used to bolt it to the wall:

Mounting flanges

When I made the sides of the chassis, I welded angle iron onto them, in order to attach said flanges:

Tabs where the mounting flanges will attach

(Note the plasma-cut hole, which will be where a removable plate with sockets for Ethernet, VGA, and USB will go).

The mounting flanges are quite thick (the wall is rough and bumpy, so the chassis needs to be spaced slightly from it), so it was good fun welding them to the much thinner angle iron. I think I did an OK job:

Mounting flange attached

Then I mounted the internal frame for mass storage devices, which goes above the processor frame, below the environment management system. It's a metal plate drilled for lots and lots of 3.5" disk drives, which attaches (with screws) to brackets I welded into place:

Mass storage frame

With all the internal stuff done, I started to weld the top panel in place, which I'd avoided in order to enable me to get access into the top:

Top panel

Annoyingly, I ran out of argon while doing the tack welds. A TIG welder without shielding gas is a lot like a plasma cutter, and I burnt a nice hole in a shower of sparks. It's only a small hole, so I'll be able to weld over it when I finish the job off.

Unable to do the final welding, I drilled a hole in the eaves, where clean outside air will be drawn in through a duct into the environment management system:

Air inlet

I also hefted the entire thing up to the wall where it will be mounted, propped it in position, leveled it, and drilled through the holes in the flanges to make the holes that will be used to anchor-bolt it in position:

Wall prepare for mounting

Workshop progress (by )

Setting up my workshop has been a long battle, thanks to the roof leaking (and everything getting covered in slime mold because of the damp, and ivy growing in through the holes in the roof and shedding sticky sap and dead leaves on everything, and a cat getting in there and pooing on the floor...). Things got rusty, everything got grimy, and stuff was moved around willy-nilly to get it out of the water; and then because everything was in the wrong places, stuff couldn't be put away properly, and so things ended up piled wherever they could go. This was quite distressing for me; by nature, I'm a person who makes things, but I've not been able to do anywhere near as much making as I'd like for years, because I didn't have a nice place to work and didn't have easy access to my equipment.

Door with sign

But, now the roof is fixed, and everything's had about a year to dry out. I've had time to continue painting the floor (it's all now covered in paint, but some parts need a second coat); I've cleaned and tidied;0 and thrown away wood and metal that was too rusted to be of any use, and scraped up the remains of cardboard boxes that had dissolved into fungus, and found and removed all the cat turds and scrubbed the floor with disinfectant; thrown away computer parts that were covered in disturbing fungal blooms; and cleaned and tidied the computer desk. I've made racks to store the wood and metal stocks that are still usable, and put down linoleum under the computer desk so the chair can roll around freely (it didn't do too well on the rough concrete) and I have a nice surface to rest my feet on.

I put up a bracket with hooks for my boiler suit and lab coats, by the door, as the place they used to hang now interferes with the material racks:

Protective clothing hanging by the door

I've got the compressor installed under the workbench, rather than kicking around the floor:

Compressor installed under workbench

And my computer desk is all set up nicely; you can't really see it here, but there's a desktop PC, with a nice set of speakers and an amplifier so I can listen to music - or the audio from my wide-band scanner, seen to the right of the monitor, which picks up the FM broadcast band nicely:

Desk

What's next? I still need to assemble some shelving, as there's still stacks of flimsy plastic crates holding a lot of stuff. And put a second coat of paint on some bits of the floor (which will be easy to get to when the crates are gone). And I've got a metal garden waste incinerator I was going to turn into a furnace (but which is far too large, and now I've helped somebody else build a furnace that he lets me use), which I need to find a new home for. And I need to find a place to store the festival trolley, which currently kicks around on the workshop floor (getting in the way and offering plenty of shin-scraping opportunity). And I need to finish the meter-and-a-quarter-high heavy steel server chassis standing in the middle of the room (which will be fixed to the wall next to my computer desk when it's finished).

I want to make a new welding bench, too - my current one is curved, as (in the wildness of youth) I tried to put far more welds between the top surface and the frame than was needed, causing it to warp. This means it's very hard to make flat things, as they don't lie flat when I'm lining them up to weld. And, as it stands on four rather thin angle-steel legs, on a rough concrete floor, it wobbles, so isn't much use to mount a vice on. Speaking of vices, while clearing up in the workshop, I came across this beast:

Old leg vice

It's a "leg vice"; the long metal leg should be embedded into the ground to steady it. It's a blacksmith's tool, intended to hold something while it's battered with a hammer; thus the exceptionally sturdy construction. If I bolted it to my current bench, then the bench would fall over if I tried to use it in earnest. We found it in the stable where we lived before, which is the ancestral home of one side of my family; I was given it as I thought I could try and get it working, although I was expecting a long task ahead of me to rebuild seized parts. Thankfully, the screw thread was in perfect condition, and penetrating oil and elbow grease got the joint un-seized, and it's now working nicely. It still needs some rust removal to make it more pleasant to touch and to avoid contaminating everything I clamp with rust, but that won't take long.

I costed up materials to make one with a more rigid frame, bolted to the wall at the back and with two legs at the front so that it wouldn't wobble (and, with the wisdom of experience, only stitch-welding it to the frame, as that'll provide more than enough strength without curving it into a bow); making that will cost a little over sixty pounds (plus welding consumables and electricity). The design includes a mounting point for the leg vice, so that it protrudes out into the room (with the top of the vice level with the top of the bench, so it's not in the way of large things going on the bench), and converting the old bench into a shelf under the new bench to provide much-needed handy storage for grinding tools and welding clamps.

However, having just spent a bunch of money on welding gear I'm not going to be in a position to splash out sixty quid on a welding bench for another month or so (let alone buying metal for other metalwork projects needed around the house, such as a set of railings for the front of the house...). Thankfully, we've found a local scrap metal merchant who are willing to let us rummage around for cheap metal! When we get a chance, I'm going to head over there and see if they have any steel plate for the top and box/angle section for the frame and legs... It'll be nice to have a good welding project to focus on with my new TIG welder!

Learning things (by )

I love learning new things. I'm usually struggling to find new things to learn; the last fun bit of computer science I learnt about was Bloom filters, and they didn't hold my attention for long. The last really fun bit of computer science I learnt about would be content-addressed storage, and I'm still having fun with that, but I can't find any more to learn about it. I'm having to make stuff up myself, which is rewarding in its own way, but much harder work.

Of course, this past week I've been learning TIG welding, which has been awesome. It's been a while since a whole new field of things to learn has opened up to me, and it's nice to work on a new class of physical skills. My routine physical learning is my weekly Krav Maga training, but I crave variety. My lust for learning benefits more from intensive two-week courses than an hour a week for years. I'd love to go and take a proper welding course at a college, but I can't spare the time; I have to practice when I can in the evenings and weekends. I'm getting good at horizontal/flat welds, but I'd like to master vertical and overhead (because if I work on anything large, such as the festival trolley, in my cramped workshop, I often can't rotate everything around to be nice and flat). Also, suspecting that the trouble I was hitting with stick welding is at least partly to do with the limitations of my old cheap AC welder, I want to use my new welder's capability to do nicely regulated DC stick welding and see if I can learn to do good stick welds. And I'd like to get some practice in welding aluminium and stainless steel, as I have applications for both of those.

So that's physical skills sorted, for now. Mentally, I've been learning how antennas work. There's no particular reason for this; it's something that's always puzzled me somewhat, but what's triggered the recent interest was a birthday gift from an old friend, of the ARRL handbook, which goes into some detail; and then meeting an interesting guy at a Cheltenham Hackspace Open Evening who turns out to design broadcast transmission antennas for a living, who answered a load of questions left open by the books. I still want to get a better intuitive grasp of the quantities involved - how many volts and amps appear on an antenna feeder line? What field strengths in volts per meter would you expect to find at what distance from an antenna? Does that relate to a corresponding magnetic field strength in tesla?

I've also been learning Morse code. This is quite interesting. I thought I'd memorise that table of dots and dashes and that'd be that, but it turns out that this technique tends to maroon people at slow morse speeds, as they mentally record a sequence of dots and dashes then mentally look it up in the table to find the letter. To get fast Morse skills, which tend to tend towards one or two characters per second, you need to learn to recognise the sound - "di di dah" - as a letter directly. So I've been using a combination of the Farnsworth and Koch methods to learn Morse; growing my "vocabulary" a letter at a time, and using an enlarged inter-character spacing. The latter is because I was tending to find that I'd hear a character, and write it down, but while I was writing it another would have been and gone, which was confusing. I want to reduce that inter-character gap, but I might wait until I've learnt the entire alphabet via the Koch method, so I can mentally be writing entire words rather than concentrating on a letter at a time - with a reduced alphabet, Morse training tends to involve writing down random gibberish (so far, I know M, K, R, U, S and O; at least the old Nokia SMS beep now makes sense to me... di-di-dit dah-dah di-di-dit!). Again, I have no particular reason to learn Morse - I learnt it as a child, but then forgot it through not using it, which had always faintly irritated me. I've often wondered about using it as a crude interface to tiny embedded computers, although it'd be frustratingly slow for most uses. The usual reason to learn Morse is to do CW amateur radio; that's an idea I've toyed with in the past, but being able to talk to random people over radio holds little appeal (I can talk to random people over the Internet much more cheaply and easily). However, I'd be interested in getting an amateur radio licence as a mental challenge, or as a means to some other project that requires radio communications capabilities, so I might go for a course if one comes up at a good time. I'd like to be able to operate a radio transmitter in an emergency situation, too.

I love to learn things, but I feel sad about not using the skills I pick up. Ok, I don't want to use my Krav skills - they tend to involve hurting people, and are only useful when already under danger of harm coming to me or people I'm protecting, which is nothing to be happy about. But I practice welding because want to make metal things. But by no means do I only learn things when I have a need for them; I learn stuff because it looks interesting and the opportunity arises, then I try and find applications. I've already been excitedly thinking about how aluminium welding will simplify the construction of one of my old back-burner projects - making a hiking staff out of aluminium tubing, that has a stack of lithium-ion batteries inside it at the base, a computer with a keyer in the middle so I can interact with it, and a high-brightness LED lantern on the top so I can have a variety of illumination options (white all around, white forwards only, red all around, etc). I had been working out complex systems of brackets and bolts to hold it all together, but TIG welding it would be much easier, neater, lighter, and stronger. Now, I had considered having a button that could be used to strobe the lights for Morse emergency signalling - and the logical next step was to include a co-axial semiconductor laser in the top that could shine a bright beam for signalling in Morse (and, at a pinch, be used to light fires; you can get 2W laser modules off the shelf these days, and all those lithium ion batteries are going to be able to source a lot of power...). So perhaps I should get a ham licence, and make the staff in sections joined together with insulators, and make it be a two-meter band dipole antenna (which is one meter long) with a CW transceiver inside, so it can also send and receive Morse by radio? That might be fun, and not much extra hardware as it'll already have a decent ARM microprocessor inside.

For now, though, I'd better focus on finishing off my server chassis (which I'm building my welding skills up towards), and make a new welding bench (mine is curved, and wobbles because the floor is uneven and the legs are too weak), and do some metalwork that's needed around the house... I'd like to do some more focussed Lojban study, too; right now I'm just picking up vocabulary by looking for words for things I don't know yet when I need them, but re-reading the reference grammar to remind myself of bits I rarely use would be good!

TIG Welding: The First Day (by )

Today, I took the day off work to take my new TIG welder for a spin.

I started by getting some pure argon shielding gas; prices for this stuff vary widely (10 litres full of gas at 200 bar for £35 plus £15 shipping, or the same for £77.90 including shipping?), but I managed to get a 9 litre cylinder filled for £25 at Target Tools and Supplies in Gloucester. They don't seem to have a web site, but they're here.

With that installed, everything worked fine:

My welding setup

I didn't have to find out how wonderful R-Tech's customer service are, because the thing arrived in full working order and was easy to set up and use 🙂 I ran a few test beads across some scrap steel, and it worked pretty much as I remembered from my TIG course all those years ago, so I set to doing something useful.

First job was to fix up the dodgy welds holding the new steering gear onto the welding trolley. I ground down the two lumpy lines of poor stick welding on either side of the join I actually wanted to weld together (it had bridged in a couple of spots, which was holding it together, but it was far from ideal), and set to it with the TIG. The result was hardly beautiful, as I didn't weld it completely flat so it was a bit irregular to start with, but with no fuss at all I was able to make it bridge the gap. I'm finding TIG much easier to control than stick - I can see what I'm doing far better, so I know where I'm welding, and because it's not constantly depositing metal, if the weld pool hasn't formed where I want it to, I can move it and make sure both sides are melting together before I start putting in filler! As I was welding a 3mm thick flat bar to a 2mm-wall 25mm square tube, getting both sides to melt together wasn't an obvious operation of just applying heat to the middle, so being able to manipulate the arc was a great bonus here.

Next, I cut off some 10mm square tube to weld onto the chassis so as to stop the steering arm from swinging too far from side to side. Originally, it was possible to steer too far, causing one of the front wheels to jam underneath the front of the main body of the trolley, which is no fun; these two stops put a stop to that! However, this was my first experience of welding something that's not horizontal and easily accessible. It was a real squeeze getting to the place they had to be welded, so I kept finding my torch hand or the hand feeding the wire in snagging on things. When attaching one of the stops, I lost track of where the filler wire was while welding; it had caught on something and was being pushed aside of where I was pointing it, outside the area I could see. While I faffed with this, I left the torch pointing at one place for too long and melted the end of one of the stops off! It wasn't a bit that does anything, so I'll probably grind it off and do the same on the other one to make them match again, but still, it wasn't great...

Also, when welding in awkward positions, I couldn't see the arc so well and kept poking the tungsten electrode into the weld pool. This meant re-grinding it, which wasn't ideal as it contains traces of thorium (a radioisotope), and you don't want too much thorium dust getting into your lungs. I decided to practice a bit with the torch in awkward positions on a bit of scrap, and got the tungsten stuck again, and decided not to re-grind it - I nipped out to a nearby welding supply shop and picked up some E3 tungstens, which aren't radioactive. With one of those ground and installed, I set to a little project: making myself a monitor stand for the office (my monitor currently sits on a stack of books).

I started with flat welds to put the top together, which went fine:

The bed of the monitor stand

Then welded some tubes onto the bottom to make legs:

The monitor stand

This was a lot harder. I've not got the correct angle and electrode stick-out yet, so was struggling to see the weld pool, and ended up dipping the tungsten in the metal a lot. Also, heat rises, so I was having to work to get the flat bit I was welding to to melt and form a pool, while the tube sticking up from it was happy to melt and then flop down, making a nice arch. I think I can fix this with better torch positioning - I need to experiment more!

As well as working on my torch holding, I think I also need to pick up some thicker filler rod - I've got a kilogram of 1mm mild steel rod, and 1mm rod seems to just disappear; I struggled to feed it in fast enough and it kept balling up. I think I had the right amperage for the metal (I was using 70 amps on 3mm thick steel with a 1.6mm tungsten), given the penetration and the rate at which the weld pool formed, so I think my rod's just too thin.

Also, I need to figure out which sized ceramic to use. I set the torch up with the smallest one (which has "5" printed on the side; I have a "6" and a "7" as well), assuming that it's best to start small and move up, but during the post-flow stage I'm seeing the surface of the weld pool rippling quite violently, and when it solidifies, it has a correspondingly ripply surface texture. I'm running the gas regulator at 8 litres/minute, an I've been recommended to go from 8 to 12 for most jobs, so I don't think the gas flow rate is too high; I suspect that the narrow ceramic is forcing the gas into a tight stream so it runs faster and blows the weld pool around.

Now, when we got a compressor, we decided to name it Compressita Wurst in recognition of the recent Eurovision Song Contest winner. Continuing this tradition, the TIG welder is, of course, called Tigger, meaning that my old stick welder is therefore now called Pooh. If I get a plasma cutter, I'll call it Piglet.

I'm delighted with my welder, and look forward to improving my technique! I've a few new projects in mind - fixing up our barbeques with new legs, welding stainless steel grilles for them, and making myself a better welding bench (I can shorten the legs on my current one and make it into a shelf underneath the new one); but my most urgent project is going to be finishing off the new server chassis!

My only complaint with the R-Tech TIG161 welder is that the power switch is all the way around at the back; to turn it on and off, I have to crouch down to reach under the shelf to the back of the thing. Do other people have a handy switch on the socket it plugs into? Or do they not shove it on a shelf? I don't know.

Ok, one other complaint. The hose that connects the gas regulator to the welder (that looks white in the picture of my welding setup), when it arrived, smelt disgusting. It actually smelt like excrement. Not precisely like excrement - it was clearly the smell of some volatiles outgassing out of new synthetic materials - but that's the closest smell that came to mind. At least this was only apparent when I had my face near it while fiddling with the hose fittings to connect it up, and the smell has subsided after a day's usage. Thank God. That's the smelliest pipe I've ever encountered.

TIG welding (by )

Back in 2008, I took a welding course, in which I fixed the mistake I was making with my stick welding, and had a go at MIG and TIG.

Now, although I learnt to make nice beads with stick welding on flat surfaces, I still struggle with various things. Much of the welding I want to do is on thin metal, so I need to run the welder at a very low current, creating a feeble arc and with a tendency to stick, and still burning through if I'm not quick. I still can't do inside joint welds (the arc sticks to one side, or the other, and rarely both).

Is it my poor technique, or am I being limited by the fact I'm using a ten-year-old arc welder that cost £50 from B&Q? When I borrow a friend's MIG welder, I do much better work, and tinkering with my technique over the past decade has failed to make a huge improvement...

Whether it's me or the welder, I know that stick welding isn't perfect for what I want to do. As well as the issue with thin materials, it can't weld aluminium. I had a stick welder because it was all I could afford at the time, and living in a small flat, I didn't want to be storing compressed gas cylinders!

TIG is widely regarded as hard to learn, because there's so many variables to control - those ten complicated-looking knobs on the welder, the movement of the torch, the fine control of current with a foot pedal, the way you feed the filler metal in. However, when I tried it, I found that I liked all that control. With a MIG, you set the power level and the wire feed speed on the machine, and then pull the trigger to weld - which is great if the settings are all correct and you're doing a long straight uniform bead. But if you're having to change position as you weld, or dealing with varying thickness of metal so the rate of conduction away from the weld varies, it's trickier to have those settings correct. And to get them right, you need to do test welds, adjust, and do more test welds.

With a TIG welder, you can vary the speed at which you move the torch (and the current, with a pedal) and the rate you dab filler metal as you work, based on feedback from how the weld looks. Although there's more to vary, there's less need for trial and error. That suits me better! Back when I did the welding course, I'd really enjoyed TIG, and found it easy to do great welds, but a MIG machine looked a lot more likely to be affordable. So I was slowly saving up for a MIG machine.

And then I found that R-Tech, a local company on the outskirts of Gloucester that make welders and are widely lauded for their quality and good customer service, offered twelve months' interest free credit.

Suddenly, rather than saving up for many months for a MIG welder, I could afford a TIG welder (and quite a good one, too), with the money I'd saved as a deposit and then sixty pounds a month for the next year. THIS CHANGES THINGS...

So, today, my new TIG welder arrived. It can go up to 160 amps, it can do AC or DC (so it can be used for aluminium), it can do pulsed power control, and it has a foot pedal for precise work. So it'll be great for thin stuff. Also, it can do stick welding, but "nicely"; DC, with good current regulation, as opposed to my old AC transformer. That should make it produce much more steady arcs, so I'm looking forward to seeing if I can also improve my stick welding with it - stick welding is worse than TIG in most respects, except that it's faster and doesn't use up shielding gas. I still have a lot of stick welding electrodes to use up, so when I'm doing work on heavier bits of metal, it'd be nice to use them if I can do so and still produce good welds!

This evening, I unpacked it, ground a tungsten, put everything together, and rearranged some shelves in the workshop to set it up. I made a hook to hang the torch on by my welding bench, checked that the right things appear on the display when I turn it on, and then sadly bade it goodnight, as I'm not getting the shielding gas cylinder for it until tomorrow.

My plan is to start running test beads along a bit of scrap steel until I seem to have got the hang of it, then do a few easy jobs - such as re-doing some of the shoddy welds I messed up with the stick welder, and adding a steering stop to the festival trolley, and fixing a bit of my welding bench that snapped off after the bottom rusted.

Once I'm confident, I'm going to finish my current big project - a custom server case for love.warhead.org.uk, which hosts this site and many others! I've been taking it to my friend's workshop to use his MIG on it, which only happens when we're both free (less than once a month), and involves folding all the seats down in the car and lugging a significant weight of steel through the house. Did I mention that this thing's 1.2 meters high, and made of 1.6mm thick steel plate?

But I'm so incredibly stoked I'm going to have a TIG welder. I'd all but given up on the dream!

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