Wednesday, October 27, 2010

Sugru hack saved my camcorder

My first camcorder was just a little bit disappointing; the zoom lense was such that it could easily film far-away stuff (e.g. I could just about make out the whitening of the pole during a Martian winter), but the field of view was way too narrow for close-up stuff (e.g. my fast-moving toddler).

I bought a wide-angle adapter, screwed it onto the filter threads on the front of the camcorder. Years of happy wide-angle filming followed... until my poor video camera drowned while surfing. I quickly bought a very similar model online... and was devastated to find that it couldn't take my old wide-angle adapter - in fact, it had no filter threads at all!

Years of miserable narrow-angle filming followed. Then, along came Sugru! The plasticine-like molding qualities and reasonable setting-time allowed me to mount my old adapter on my new camera (which had an awkwardly sloping non-perpendicular front end) and to get the optical alignment just right (I left the camera on while hacking so I could check for problems with focus or vignetting).

Wide-angle adapter mounted with (blue) sugru

I'm thrilled with the result - the camera is maybe slightly less pretty, but I can squeeze a lot more world into each frame. My wide-angle adapter is now a permanent feature of my camera - and I like it that way.

Tuesday, August 3, 2010

Reviving an old laptop: Puppy Linux

We have a shiny new laptop with a lovely wide screen and a multi-core processor; we love it very much and use it a lot. Meanwhile, our old laptop has been sitting idle - even when it would be handy to have a second laptop handy for some really essential web-browsing, we couldn't bear the eons-long boot-time and the extremely sluggish browsing experience that followed.

That bothered me; I started out on a 386 with a 25MHz processor 2MB of RAM, back when that wasn't a bad machine. Now, a 1.6GHZ machine with 512MB of RAM is too slow for me? Insane! I could have re-installed Windows XP (again), and that would have helped; maybe added a little extra memory. Instead, I opted for something a little more radical: Linux. Now, once upon a time, Linux was scary: an OS that was fast and stable, sure, but only for those who enjoy knitting their own device drivers of a winter's evening.

No more! Today, a wealth of Linux variants awaits, and initially I was thinking in terms of Ubuntu or SUSE. However, my quest for speed pushed me to look for ever-smaller distributions (Linux variants), until I came upon Puppy Linux - which, like its namesake, is small, friendly, and fast-moving - the download is only around 100MB. Burnt to a CD, this cool little OS is ready to go; I just popped in my laptop's CD drive and was able to boot into Puppy Linux straight from the CD without even installing it! I was very impressed to find that Puppy had no problem recognizing all my hardware, requiring absolutely no input from me to get the screen and speakers up and running - even my network and internet access via USB wifi dongle were handled easily - a far cry from my last Windows XP installation experience, which required much downloading of device drivers. Puppy is much friendlier than that!

Puppy turned out to be very, very fast, extremely responsive, even on this old laptop. Being so small, the whole OS easily fits in RAM; no churning hard disks here. Puppy even comes pre-loaded with a decent web browser, word processor, spreadsheet, vector graphics app etc. - so you can do quite a bit without installing any other software (and all these applications are just as nippy as the OS itself).

Having run Pupppy from the CD, I was totally sold; I copied all personal files onto a portable hard drive and nuked the laptop, opting for a clean Linux install (drastic, but easy to do). Now, that same old laptop we could hardly bear to use will boot from cold in 45 seconds flat. After that point, you can click something and have it launch instantly - whereas Windows, in my experience, shows you the desktop as a placatory measure, while it continues frantically to load things in the background.

In summary, reviving our old laptop with Puppy Linux was very easy and quick - much easier than re-installing Windows, and much cheaper than a hardware upgrade (it only cost me the price of a CD-R). My old machine is now an absolute pleasure to use, and I'm looking forward to filling up all the hard-disk vacated by Windows with some Linux-only apps I could never previously have run.

Wednesday, July 28, 2010

Printing in 3D with Shapeways: a review

I still remember the magic of listening to my first printer (dot-matrix) clattering into life, and of watching as, ever so slowly, blank paper went in and printed words and pictures came out. It was an amazing moment of creation; how far removed from the painstaking effort of calligraphy or hand-sketching!

One ring to bind them...

Today, I opened a small cardboard box full of polystyrene chips and dug out a small packet. Within the packet, a single object, unique in the world. I had last seen it on my computer screen as 3D model which I created with the excellent NURBS modeller MOI (Moment Of Inspiration). This object - a simple wedding band - has been "printed" in 3D using a mixture of stainless steel and bronze, then sintered and finally gold plated, all by a company called Shapeways operating in the Netherlands. The same company offer a variety of other materials, including several plastics and glass. They also offer some lovely metal finishes apart from that pictured above (matt gold). For me, the combination of being able to make an object in a durable metal form, and to have the freedom to create my own one-of-a-kind was extremely exciting.

So, how did it turn out?

The good: very easy to use. Upload your model, wait for them to check it can be printed, then choose a material and await delivery. My order (this ring) turned up well within their specified timeframe.

The not-so-good: 3D printing is still in its infancy (and Shapeways are upfront about this), and, like my old dot matrix printer, the resolution is not yet pin-sharp. The digital model of the above ring is perfectly smooth, and the thin transverse pits are a product of the printing process. I like to think of it as fattura, the Italian term for the imperfections that reveal how a thing was made.

Taking this service for what it is - a very accessible route to rapid manufacturing of small numbers of prototypes, toys, jewelry based on slightly experimental technology - and you will, like me, be a very happy customer.

Wednesday, July 21, 2010

Sugru: almost too much fun

I'm very enthusiastic about fixing broken things (some might say this could have something to do with how often I manage to break things). A steady stream of small repairs pass across my workbench - a little bit of carpentry, gluing, riveting, fibreglassing, etc.

Sugru in action

Plastic, though, has always been a problem - until now. I've recently got a little packet full of sachets of a new "wonder material" from . The 50g sachets contain a material which looks and handles a lot like plasticene - very easy to shape and mold. Unlike plasticene, it starts to set about 30 minutes after coming out of the sachet. The really neat thing about it is that it sticks very well to whatever I've put it on. So far, I've repaired a screwdriver handle(plastic), a plastic basin with a long thin crack, a couple of long gashes on my brothers wetsuit (neoprene), and put a little blob on my gate (steel) to keep its bolt a little quieter.

Any negatives? Well, it does come in sachets, so once you open one, it's a use-it-or-loose-it situation. So far though, this hasn't been much of a drawback - it is so easy and fun to use, you'll just be looking for things you can stick it to.

Monday, May 31, 2010

Making a rudder, part 4: designing gudgeons

With my rudder blade is almost ready for the water, so time to think about it can connect to the boat. To hang it from Briongloid's stern, I need to make a pair of gudgeons; these will allow it to pivot about a vertical axis, and need enough strength to prevent it either from being swept astern or from bobbing up out of the water (the Corecell interior being much less dense than water, the finished rudder is going to be quite buoyant, even with much of the length out of above the surface). Also, we are now talking about a moving part, and so friction is a problem: the gudgeon needs to pivot about a stainless steel pin without appreciable wear to either itself or the pin. Two separate mechanical challenges for our gudgeons: what materials should we use?

Figure 1: Gudgeons (yellow) allow a transom-hung rudder (blue) to pivot about a vertical axis (red)

To give the parts the necessary strength (tensile strength being what they need most), I have decided to imitate the gudgeons that held the old rudder, which were made in stainless steel and worked fairly well. However, I can't work in stainless steel (no skills, no tools, no materials), so I chose a different material, more impervious to corrosion and with even more impressive tensile strength: carbon fibre (weight for weight, the median sample of carbon fibre has six times the tensile strength of stainless steel [Source: Wolfram Alpha]. This can be bought as a woven fabric, just like fibreglass, and worked with the same simple tools - epoxy resin, a pair of scissors, etc (Kevlar needs special shears, but ordinary scissors will do for "mere" carbon fibre). Strength problem: solved.

So much for strength: what about friction? This is a moving part, a type of bearing, and Mr. Friction is not our friend. The pivoting action of the gudgeon around the steel pin is going to cause wear if I just use epoxy-impregnated carbon fibre. For the core of the bearing, a different material is required - strong, but also slippy. After some research, I found the solution on the excellent blog of a Canadian who is building "Raven", a nippy trimaran from Ian Farrier's F22 design. This gentleman used a plastic PET-P, Polyethlyene Terypthalate, also sold as Ertalye, in just the same situation. This particular wonder material shrugs off water, is nice and slippy, and and also pretty strong. With a little research, the amateur builder can buy small quantities in rod or sheet form. Just the thing for the core of our bearing.

Figure 2: Gudgeon cores (carbon fibre ties not pictures)

Figure 2 above illustrates the core of the gudgeons, with the long base of the triangle being mounted on the leading edge of the rudder itself. Layers of carbon fibre cloth around the outside bind the core to the rudder in a continuous loop for maximum strength. The hardwood insert is there just to save some epoxy (cut from the ruined old rudder, it saves me a few pence worth of epoxy and provides similar strength). The hole in the centre of the PET-P cylinder is where the pintle goes, so the gudgeon can fulfil its pivoting function.

Coming in the next post: making and mounting the gudgeons

Previous posts in the series:
Designing a rudder, part 1
Designing a rudder, part 2
Making a rudder, part 1

Sunday, April 11, 2010

Taking the long way around

In which no rudders are mended, but some beautiful footage is watched.

As the weather finally warms enough for epoxy to set and my boat repairs to continue, I'm looking forward more and more eagerly to (re)launch day. Until then, perhaps the next best thing is to watch a man called Dylan Winters circumnavigating Britain, very slowly in "the slug", a Mirror Offshore (19 feet, with inboard diesel, designed by Van de Stadt, the same man who designed my own poor Briongloid).

What makes an already-ambitious trip even longer and more impressive is that Mr. Winters is not taking the shortest route. Instead, he sails as far as possible up every river of interest along the way - from giants like the Thames, to tiny backwaters like Beaumont Quay (up a canal dug by slaves in Roman times). Along the way, he takes beautiful HD footage of boats large and small - lately, gorgeous Thames barges have been a recurring them.

A professional film-maker and seasoned editor, his films come with illuminating commentary on the history of the places he visits, and his lovely shots of sea and river are complemented by lovely soundtrack by the likes of Cities of Foam.

Enough talking; if you take even a passing interest in things boaty or the British coastline, do yourself a favour and wander over to Keep Turning Left. Well worth the price of admission.