Saturday, 16 March 2013

Evolution of 3D Printing

3D printing, that amazing technology that has recently grasped the media's attention, evoking comparisons to Star Trek's 'replicator' that could assemble any known object out of its basic molecules. Behind all the hype, what can it do, and will it really change our world?

Sunday, 10 March 2013

Winter Finishing Touches on a Windbreak

So, for a well-overdue update of what's happened this winter of 2012 to '13, some of the useful things I learned, whether hard lessons or delightful ones, are as follows:
While I saw most of the annual plants that I put out demolished either by slugs or sheep, and only got a few halfway-decent fruit from Alpine Strawberries in their first year of planting, the only significant food crop that I was able to grow in spite of all that and the mostly unfettered hard winds came from a very unexpected place. A bunch of radish seeds that I had sowed on compost mostly next to a plum tree and a few other spots were taking off very healthily.
I had mistaken them for turnip plants at the start of autumn when they brought out lots of pink flowers, but upon pulling one out to thin them down, I discovered that not only were they radishes, but the root growth was utterly terrible, no larger than a single chick pea and very woody by the time the plant was in flower, so I left them to self-seed, until I got this surprise as their flowers fruited...
It turns out that radishes grow not only an edible root crop, but also some tasty little seed pods (only roughly similar pea pods in shape), which were very nice when sliced into salads.
See the root of the plant that I plucked these off of; it was tiny in proportion to the above-ground part of this plant, although I shouldn't really be surprised when growing root crops in rocky soil.

Sunday, 4 November 2012

Prep to Prototype

On the way to prototyping my ducted wind turbine design, there have been a few silly setbacks as usual with 3D printing, and that's before even mentioning how awkward part sourcing is when no one supplier ever has everything you need, and I end up forced to waste postage on a few orders just to get electronics to build a data-logging controller with. Also I'm writing this for a second time since Blogger ate my post by erroneously bringing up a blank workspace one morning after I was 90% through this post, and saving over it before I could close the tab. Unlike those lovely etherpads, there was no writing history to revert back to.

I've brought this reprap to its working limits in a couple of different ways over the last few weeks, firstly with a bespoke drill-guide that I made in a similar way to the dremel cutting kit only super-sized so as to allow a cheap hammer drill to make nicely perpendicular holes in the absence of a drill press.
A trouble with this print is its huge width compared to the narrow surface area actually in contact with the print surface, which meant that, being a PLA prototype, it could barely adhere to the kapton-taped surface strongly enough to stay down. When some overhanging edges started to curl up slightly, the resulting light collisions with the extruder head caused the wider of two parts to start lifting up off the printbed with an audible crack. I found a quick fix to keep that part in place before the whole surface dislodged.
Bulldog clips and small allen keys were handy, so they held the part down.
This print was eventually successful, but not before another limit in size surprised me.

Tuesday, 4 September 2012

Practical Plants

A new website launched in the last month that could be a powerful tool for Permaculture designers worldwide. At Practical Plants, produced by a web developer and a writer who are together also building an organic farm in northern Spain, the huge database provided by Plants For A Future has been forked in a wiki format, while retaining database-search functionality and adding a beautifully-styled new interface, so that hopefully the information brought from that old database can be improved by weeding out inaccurate or incomplete information and using better sources.
Practical Plants beta homepage
While PFAF has primarily focused on species appropriate for a temperate climate, Practical Plants aims to cover information on species in all climates on Earth, while adding other useful structural information to the database such as companion-planting guilds. Various practical uses of each plant will now be linked clearly to relevant parts of the plant, for instance to help people avoid eating unpalatable or toxic bits of some plants. This extra structure needs some tidying to install though since it wasn't already in the existing database structure, so why not help out when you have a moment?

Thursday, 16 August 2012

Every Sheep Has a Silver Lining

With the Elaeagnus shrubs that suffered greatly after I planted them outdoors a few months ago, for a pair of evergreen species to lose most of their leaves during spring, I was understandably worried that they would die due to root shock and waterlogged soil.
What's more, they seemed to be completely over-run by local 'weeds' to the point that I couldn't see this one.

However, since the tiny forest garden that I'm pioneering was slightly chewed up by marauding sheep a couple of weeks ago, I've spotted signs that they are getting some strength back, and noticed some of the other plants that I stuck out growing vigorously.

Saturday, 11 August 2012

Printing PLA on Paper

A few days ago I started doing tests of 3D-printing PLA using paper as a build surface, since I previously saw it briefly trialled with some success.

My first test mimiced Doxin's test by simply using cheap white A4 printer paper. The first things that I tested printing on the plate were: a new and more robust axle support for my spool stand, and a couple of the ball-joint pole-end-caps for EFFALO's 2V geodesic dome connector set. The paper wasn't clamped down very well since I could only find 4 bulldog clips at the time, and had wrinkled up either end of the paper slightly when attempting to clip it with its longest side in the X-axis before settling on having it along the Y-axis.
Paper set up for first test.

Saturday, 4 August 2012

Lessons in Rapid Prototyping and Design

Never before did I realise what a huge difference software and firmware can make to 3D-print quality.

Not long after setting my reprap up again in its new home, I found it having problems moving in the Z-axis, where the motors would refuse to move half the time, which after describing it on IRC people helped me figure out that the controller was telling the motors to accelerate too fast.
The acceleration that had been implemented in June 2011 Sprinter firmware still caused a significant amount of 'jerkiness' in axis movements. By updating to the latest version for June 2012, not only did more appropriate acceleration, adjusted by a predictive 'look-ahead' buffer, improve this current problem, but it also cut out a vibration problem that broke my Y-axis last year, by pausing at the end of each move for a few ms, when making very short successive movements in order to draw a narrow zig-zag fill line. This helps because in most stepper-motor use there is no feedback control mechanism - the idea being to move a set number of steps then lock in place and hope for the best, which in reality can result in nasty vibrations. By stopping for a moment, the transient vibrations resulting from overshoot can settle, so there is less chance of them feeding into some resonant frequency and shaking the printer to bits.
Illustration of overshoot, via Wikimedia Commons.

In the new firmware a minimum temperature is now set by default, which might have prevented another previous incident that I had with over-heating when a thermistor connection broke.