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.

Friday, 3 August 2012

It Hits The Fan

Gardening in a region where you're almost always surrounded by sheep has its obvious pitfalls...
Sometimes those sheep or their mischievous little lambs find a way past the fences you put up, because they can see that not only is the grass greener on the other side, but there are also tasty things other than grass to chew on.

One or more of those sheep got over a fence recently and wreaked havoc among the crops I'd planted, trampling some while eating the tops off others...
They seem to love eating fiddleneck flowers