Steel Pan Drum Making (by sarah)

Dear Alaric and Jean you asked for ideas for welding projects for presents for me - you know already that I would like a tank drum but I would also like what I call a Calypso Drum - these used to be used at the carnivals when I was a kid and also during the candle light parades and things. I prefer the ones without drilled holes but if they are easier to make then that is fine 🙂

This one looks like a lot of work - from having spent time round industrial workshops as a kid I kind of had it in my head you just bashed empty oil cans - the sort my bro/uncle David makes into BBQ's. And I'm sure there was a drum made from the bonnet of a car or maybe they just let me play with non-sharpe metal and stuff to keep me entertained as a kid!

Also there is this little beaut which is painted and stuff - I didn't know they came painted - it is lovely but about £80 and isn't as many notes I don't think.

<

iframe style="width:120px;height:240px;" marginwidth="0" marginheight="0" scrolling="no" frameborder="0" src="//ws-eu.amazon-adsystem.com/widgets/q?ServiceVersion=20070822&OneJS=1&Operation=GetAdHtml&MarketPlace=GB&source=ac&ref=qf_sp_asin_til&ad_type=product_link&tracking_id=httpwwwsnellp-21&marketplace=amazon&region=GB&placement=B00V4UF4PG&asins=B00V4UF4PG&linkId=&show_border=true&link_opens_in_new_window=true">

p.s. you might need to enlist the help of musicians in Cheltenham Hackspace for tuning though Jean you are always moaning at my wrong notes so you should be able to do it yourself! Remember Alaric you do have oscillerscopes!

Towards the Family Mainframe (by alaric)

Last September, I posted progress on the construction of our domestic mainframe. To recap, the intent is to build a dedicated home server that's as awesome as possible - meaning it's reliable, safe, and easy to maintain. That rules out "desktop tower PC in a cupboard" (accumulates dust bunnies, gets too hot, easily stolen, prone to children poking it); "put a 19" rack somewhere in your house" is better, but consumes a lot of floor footprint and doesn't fix the dust bunny problem. So I've made my own custom steel chassis; fed cold air at pressure via a filter, incorporating a dedicated battery backup system, locked and anchored to the wall, and with lots of room inside for expansion and maintenance.

Since that blog post, I've finished the metalwork, painted it with automotive paint using a spray gun (which was a massive job in itself!), fixed it to the wall, and fitted nearly all of the electronics into it.

A significant delay was caused by the motherboard not working. I sent it back to the shop, and they said it was fine; so I sent the CPU back, and they said THAT was fine; so I sent both back together and it turned out that the two of them weren't compatible in some way that was solved by the motherboard manufacturer re-flashing my BIOS. That's now up and running; I was able to use the HDMI and USB ports on the outside of the chassis to connect up and install NetBSD from a USB stick, then connected it to the network and installed Xen so I can run all my services in virtual machines. It's now running fine and everything else can be done via SSH, but the HDMI and USB ports are there so I can do console administration in future without having to open the case (unless I need to press the reset button, which is inside).

The one thing it's lacking is the management microprocessor. I've prototype this thing on a breadboard and written the software, but need to finish off the PCB and cabling: but it will have an AVR controlling three 10mm RGB LEDs on the front panel, and three temperature/humidity sensors in the inlet and outlet air (and one spare for more advanced air management in future). But the idea is that the three LEDs on the front panel will display useful system status, and the environment sensor data will be logged.

Here's what it looks like from the outside; note the air inlet hose at the top left:

The socket panel on the left hand side worked out pretty well - 240v inlet at the bottom, then on the aluminium panel, three Ethernets, HDMI, and USB (my console cable is still plugged into the HDMI and USB in the photo, which won't usually be the case):

And here's the inside, with lots of space for more disks or other extra hardware; the big black box at the bottom is the battery backup system:

Now I have Xen installed, I'm working on a means of building VMs from scripts, so any VM's disk image can be rebuilt on demand. This will make it easy for me to upgrade; any data that needs keeping will be mounted from a separate disk partition, so the boot disk images of the VMs themselves are "disposable" and entirely created by the script (the one slightly tricky thing being the password file in /etc/). This will make upgrades safe and easy - I can tinker with a build script for a new version of a VM, testing it out and destroying the VMs when I'm done, and then when it's good, remount the live data partition onto it and then point the relevant IP address at it. If the upgrade goes bad, I can roll it back by resurrecting the old VM, which I'll only delete when I'm happy with its replacement. This is the kind of thing NixOS does; but that's for Linux rather than NetBSD, so I'm rolling my own that's a little more basic (in that it builds entire VM filesystems from a script, rather than individual packages, with all the complexities of coupling them together nicely).

I'm using NetBSD's excellent logical volume manager to make it easy to manage those partitions across the four disks. There are two volume groups, each containing two physical disks, so I can arrange for important data to be mirrored across different physical disks (not in the RAID sense, which the LVM can do for me, but in the sense of having a live nightly snapshot of things on separate disks, ready to be hot-swapped in if required). I still have SATA ports and physical bays free for more disks, and the LVM will allow me to add them to the volume groups as required, so I can expand the disk space without major downtime.

So for now it's just a matter of making VMs and migrating existing services onto them, then I can take down the noisy, struggling, cranky old servers in the lounge! This project has been a lot of work - but when I ssh into it from inside the house (over the cabling I put in between the house and the workshop) and see all that disk space free in the LVM and all the RAM waiting to be assigned to domU VMs that I can migrate my current services to, it's all worth it!

The family mainframe (by alaric)

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:

With the frame in place, it looks like this:

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:

And here's the lower one:

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:

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

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

(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:

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:

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:

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:

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:

Workshop progress (by alaric)

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.

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:

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

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:

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:

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 alaric)

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!