Introduction to printing in another dimension

Mankind, it would appear, owe a great deal of their evolutionary advantage to using tools. This ability appears to have been massively amplified by our creation of machine tools.

A machine tool is widely defined to be a machine where the movement of the tool (the tool path) is not directly controlled by a human. One of the first known examples is a late 15th century lathe used to cut screw threads . The Industrial revolution was intimately interconnected with the creation of new machine tools and arguably by the mid 19th century all the distinct subtractive machine tool types had been discovered.

I ought to explain the word subtractive in this context, it is a pretty simple and rather arbitrary distinction (but important for this discussion). Traditional machining removes or subtracts material to obtain a finished item akin to a sculptor revealing the statute from within a block of stone by using a chisel and hammer. The corollary to this is, unsurprisingly, the additive process where material is added to create the finished item.

The machine tools from the 19th centuary were primarily single use devices controlled by gears and link mechanisms. Although the Jacquard loom was well known, because of the physical engineering difficulties, combining the concept with a machine tool to create a programmable tool path was not fully realised until the opening of the 20th century.

In the late 1940s electrical motors and punch cards/tape made machine tools Numerically Controlled (NC) and when computers arrived in the 60s we gained Computer Numerical Control (CNC) and the opportunity to completely screw things up with software became available.

With the advent of CNC additive systems became practical and by the late 1980s these machines were being widely used used for Rapid Prototyping.

The first additive systems generally used was the simple pen plotter which added ink on top of paper and became popular in draughting offices for producing blueprints etc. Though more generally thought of as computer printing technique plotters owe their heritage to CNC machines.

Next came prototyping systems based on layered object manufacture which cut shapes in a thin flat material (paper or plastic) and glued them together. These systems were expensive compared to casting processes (use a subtractive machine to make a mould and cast the part), extremely wasteful of source material and the results can be of variable quality. Systems based on this process are still manufactured and used.

Then came the stereolithography approach which scans a focused UV laser to cure resin and build up an object. There are several commercial machines available and even some home built systems but the costs of the resin have not yet made this approach generally cost effective.

Currently the most common commercial rapid prototyping additive systems are selective sintering processes where either an electron beam or a high power laser melt a layer of powdered material on a bed, the bed is lowered, more powder added and the process repeated. This process can use many different types of material and is very flexible as the power used can be plastic or metals. The quality is very high and high resolutions are available. Unfortunately these machines are expensive and generally start around £20,000 which puts them out of most individuals reach.

If anyone is still reading here is the summary of what we have covered so far:

• Humans have used tools since they stopped being monkeys.
• More than a century back we figured out how to make machines control the tools.
• Fifty years back we made computers control the tools, before this all tools were subtractive.
• In the last twenty years we have discovered several expensive ways to make objects with additive methods.

Now we get to the promise of the title, in the last few years Fused Filament Fabrication has become a viable option for a hobbyist. This method extrudes a thermoplastic through a nozzle and constructs an object one layer at a time from the bottom up.

The RepRap project at Bath university helped kickstart development of a plethora of practical operational 3D printers that can be built or bought. These machines are relatively inexpensive (starting from £400 if you build it yourself) and the feedstock is also reasonably inexpensive.

In another post I will discuss the actual practicalities of building and running one of these devices and looking at their software.

Electricity is really just organized lightning.

I have recently been working on a project that requires a 12V supply. Ordinarily this is no problem my selection of bench supplies are generally more than a match for anything I throw at them.

This project however needed a little more "oomph" than usual, specifically 200W more. Funnily enough a precision variable output bench supply capable of supplying 20A are rare and *very* expensive beasties.

So we turn to a fixed output supply, after all I will want to run my project without hogging my bench supplies anyway. These can be bought from various electronics suppliers like Farnell from around the £50 mark and Chinese imports from Ebay sellers start around the £20 mark.

All very well and good but that is money I was not planning on spending and possibly a month of waiting for an already badly delayed project. So I decided to Convert an old ATX PSU into a 12V source. This is not a new idea and a quick search revealed many suitable guides online. I had a quick skim, decided I did understand the general idea and ploughed ahead.

Wikipedia has a very useful page on the ATX standard complete with pinout diagrams and colour codes. The pile of grey box ATX supplies available on my shelf was examined and one was helpfully labelled with a sticker proclaiming 22A@12V and we had a winner.

Opening the case of the donor 450W CIT branded supply revealed a mostly empty enclosure with the usual basic switching arrangement. I removed most of the wire loom aside from two of each output voltage (3.3V, 5V and 12V i figured the other voltages might be useful in future) and three commons, the 3.3V and 5V sense lines were also kept. Each of these pairs were cut to length and leads were wired to 4mm sockets.

The "PWR_EN" line was wired via a toggle switch to ground so the output can be switched on and off easily. The 5V standby and a 5V output line were wired to a green/red bi-colour LED (via 270Ω current limit resistors) to give indication that mains is present and when the output is on.

Holes were drilled for four 4mm sockets an indicator LED and a switch. The connectors and switches were all mounted in the PSU casework. I plugged it all in, put an 8.2Ω load resistor on the 5V line with an ammeter in line and a voltmeter across the 12V rail.

I turned the mains on and the LED lit up green (5V standby worked) and when I flicked the output switch the LED turned orange, the 12V line went to 12V and the expected 0.6A flowed through the load resistor.

Basically, Success!

I have since loaded the supply up to the 200W operating load and nothing unexpected has happened so I am happy. Seems converting an ATX PSU is a perfectly good way of getting a 200W 12V supply and I can recommend it for anyone as cheap as me willing to put an hour or so into such a project.

A year of entropy

It has been a couple of years now since the release of the Entropy Key Around a year ago we finally managed to have enough stock on hand that I obtained a real production unit and installed it in my border router.

I installed the Debian packages, configured the ekeyd into EGD server mode and installed the EGD client packages on my other machines and pretty much forgot about it.

The recent new release of the ekey host software (version 1.1.4) reminded me that I had been quietly collecting statistics for almost a whole year and had some munin graphs to share.

The munin graphs of the generated output is pretty dull. Aside from the minor efficiency improvement in the 1.1.3 release installed mid December the generated rate has been a flat 3.93 Kilobytes a second.

The temperature sensor on the Entropy key shows a good correlation with the on-board CPU thermal sensors within the host system.

The host border router/server is a busy box which provides most network services including secure LDAP and SSL web services, it shows no sign of not having enough entropy at any point in the year.

The sites main file server and compile engine is a 4 core 8 gigabyte system with 12 drives. This system is heavily used with high load almost all the time but without the EGD client running has almost no entropy available.

The next system is my personal workstation. This machine often gets rebooted and is usually turned off overnight which is why there are gaps in the graph and odd discontinuities. Nonetheless entropy is always available just like the rest of my systems ;-)

And almost as a "control" here is a file server on the same network which has not been running EGD client (Ok, Ok already it was misconfigured and I am an idiot ;-)

In conclusion it seems an entropy key can keep at least this small network completely filled up with all the entropy it needs without much fuss. YAY!

Can you just...

I should have learned by now, no sentence that starts "Can you just" ever ends well. In my experience it means someone else has misunderstood the problem at hand. Then we proceed to the part of the project where (according to my lovely wife) I end up using my condescending voice.

I work through what I have been asked for and eventually, if it goes well you end up defining what the actual, real job needs to be done is. And almost envitably the "Can you just" has become a major job.

Most of us I fear recognise this "pattern" from our working lives with software. Well I am glad to report this pattern exists in real, physical world too.

Last week we took a trip to my parents in law, two thoroughly nice people (I lucked out, no evil mother in law here). I had been asked before I went "Can you just fix the garage door, it sticks". So I took along some basic tools expecting to lubricate a hinge or something.

Turns out it was the garage back door (for humans to get in and out) and...well there were bigger issues. The door frame was rotten and the door had pulled it away from the wall. So a new door frame you say? ah, well, yes

At some point in the past someone had fitted a double glazed window and had, kinda removed the lintle above the door and window! Yes there were several courses of brick masonry wall resting on top of a upvc window frame. The door frame had provided some support till it rotted and fell apart.

The window was under a huge strain and was actually 5cm shorter at one end than the other. The brickwork was no longer mortared and could better be described as a pile of bricks held together with caulking.

So my bank holiday weekend was spent removing those bricks, making good, building a frame from 44x97mm planed timber bolted into the walls and covering it with weatherboard. OK it is not masonry but on the other hand it will not be falling on anyone's head any-time soon.

And before anyone comments, yes that frame is true, the spirit level says so. Alas that window frame is very, very wonky indeed and the wall it is sitting on is 4cm out too, so It looks a bit off.

Possibly not my best work but you can hang a couple of hundred kilos from the frame and it not budge so I think its solid enough for this purpose.

Providing my father in law keeps treating it with the wood preserver every couple of years it will not go rotten either and should last a long time.

Shedding

For some time now Melodie has wanted more outside storage.

The current outhouse is an 3 foot by 8 foot converted outside toilet. Due to its age (built 1884) this building is no longer watertight and is generally disintegrating at an alarming rate. One day soon it will have to be demolished. That day has not yet arrived, instead we purchased a plastic shed.

Unfortunately the only viable place for the new shed was next to the old one, this required removing a six foot section of flower bed complete with ivy, bamboo and an old sink.

Last Saturday I completed this removal and lay a concrete base ready to take the new shed. You would not think such a small area (2.8m square) would require so much material and effort to concrete over. 300Kg of 3:2:1 aggregate:sand:cement concrete mix went into the hole along with 100Kg of instant set concrete (for a rapid surface in the changable weather).

Thursday afternoon Geoff (my nice helpful neighbour) offered to assist me in the assembly of the shed. I re-arranged my work schedule (yay home working) and after three hours the shed was assembled.

This morning it occurred to me that my webcam had recorded a time-lapse movie of the construction. I uploaded it to YouTube and present it here for your amusement.

It is a bit breezy

The weather has been a bit odd round here for a while now. The snow storms in December and early January were a mild inconvenience for me but as I work from home the advice not to travel was not too much of a problem.

It seems however that now February is here and the snow is gone we are in for some pretty strong storms. This actually affected me today when my neighbours garden wall was blown over!

As you can see my nice new IP camera captured the event, well OK the frame before and after but you get the idea. Unfortunately for my neighbour the wall collapsed onto his pickup causing extensive damage.

A short time later when my weather station was recording gusts well over 50mph nearby drains started flowing the wrong way and it became a case of water, water everywhere!

It seems that when the new buildings were erected a few years ago that the architect while maximising used space on the building plot may have inadvertently created something of a wind tunnel.

The Gap between our properties is on a parallel (north to south) to the valley below. The wind seems to travel along the crest of the valley and be funnelled through any spaces between the houses. Fortunately the rest of the properties on green lane are pretty old and the spacing between is very generous and the funnelling effect is minimal.

I wonder if we could fit a wind turbine in there? Alas it was too much for my secondary anemometer which is now smashed in three parts.

Also gaining access to the gable end wall of my property has become somewhat perilous (Hence the wonky APT antenna I cannot get fixed). Yes that really is a guy balancing on a ladder 10m high in a strong wind. And indeed the platform the ladder is resting on is built from scaffolding board wedged between the houses.

I guess the hospital emergency room being 300m away means medical assistance is on hand, even so he is braver than I am. So my weather satellite imagery will just have to come from the internet like everyone else's for a while.

New Video Camera

Last week they boys were playing with their remote control car in the snow (which was fun) and Alex wanted to record what his car saw. I immediately dissuaded him from the idea that he can use the family's DV camcorder taped to his car!

Later on that day though I saw a rocket project on LMR which used a micro camera and suggested such cameras were available from ebay very cheaply. I did a quick search and ordered on from a UK seller at £15 plus £2.99 pnp and thought no more of it.

This afternoon the camera arrived and it really is tiny and Alex is already scheming of ways to use it in addition to attaching it to his RC car.

The video output is low quality (very blurry in low light) and I have yet to figure out how to disable the time stamp (which is wrong) but it does indeed record video to the storage and can download it via USB and played using VLC.

So if you want a tiny video camera (and an 8Gig micro SD card) which is so cheap you do not care if it gets broken, I can recommend these.