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Laser cut numbered pegs for workmen

7 Nov


We had a tradesman coming out to do some “stump munching” of some of our (large) supply of stumps. We only want a few done, and some of them are in the deep grass. So, laser cutter to the rescue.


Here’s the laser cutter chopping out some mdf numbers – about 80mm wide x 140mm high. Mdf is 3mm thick, but I should have used 6mm.


For a quick job, they came out ok. The bright yellow plastic would be really good for this but it’s PVC. Cutting pvc on the laser will rot your lungs from the hydrochloric acid vapour. Worse, it damages the optics of the laser!


A very quick spray paint with flourescent pink from a rattle can.


Some cheap bits of wood. Once again, a box of kindling from the supermarket.


Bits of wood pointed on the mitre saw, and pink numbers stapled on with the air nailer.


These did the job. You can see them from some distance. Next time I’ll use thicker material as the staples pulled right through on a couple when I hammered the stake into the ground.




Cheap laser engraved plant markers

5 Oct


We recently planted a whole heap of berry plants (Cranberries, Chilean Guava, Orangeberry, Loganberry, Boysenberry, Blueberry, Blackberry, Black Currant, Red Currant, Gooseberry, Pomegranate, and Strawberry).  They came with stickers, but we wanted something more permanent.



This is the berry patch (and the neighbour’s house)  it’s hard to tell but there’s about 50 plants in there, excluding the 100 stems of raspberry.


I bought a cheap ($7) box of kindling from the supermarket. These boxes came with various sizes of wood, but the one I picked had a lot of 300 x 50 x 10 (about 12″ x 2″ x 3/8″) pieces, at least at the top. I probably got at least 20 good pieces out of the box, and the rest was good kindling anyway. I imagine this is all cheap pine (roughsawn).


The result was not bad, certainly good enough for a quick and dirty marker. My first experiment was the one at the the top (Orangeberry). This was RASTER engraved and ended up about etched about 1mm deep. It was clear and readable, apart from the smoke damage at the top. The downside was that it took ages to burn – nearly 20 minutes just for one marker.

Inkscape, once again, came to the rescue. There’s a very handy extension under Extensions – Render – Hershey Text, which takes text and writes it in VECTOR format, using the sort of fonts that were used by pen plotters in days gone by. It’s very readable, and far, far, faster. The slowest label above took under 30 seconds to draw.

Note: Tucked in the documentation was a suggestion to run Path – Simplify on the text produced. This only takes a moment, and it does smooth out the text and make it look nicer.



These were the engraving parameters I used on my 80W CO2 laser. Basically 85%, but reduced slightly on the corners. However, to make the text more readable, I mis-focussed the laser. I set the focus distance with a 12mm thick block sitting above the target. This made the lines quite a bit wider. Interestingly, it also changed the cross section to a much more V shape, rather than the usual |___| shape.









A 1919 farming robot

25 Jul

Not what I’d call a sophisticated machine, but interesting none the less. From May 1919 Popular Science magazine:

This Farm-Hand Never Tires or Asks for Pay

It was not alive, apparently, and no human being seemed to be concealed about it, and yet the thing was seen cultivating a ten-acre farm in New jersey. Down the rows of corn it went all alone, and never bruised a blade or chopped a root. It was uncanny to anyone who had never beheld each a sight before, and even to some who had.

  • The furrows between the rows of dwarf corn are made by plows automatically steered.

It worked some nights, too. Dimly outlined in the white moonlight, it could be seen threading its way with almost human intelligence and with mathematical precision, while the farmer slept peacefully in his near-by mansion and dreamed of waving corn-tassels. Around and around the field the thing moved, around a center which it continually approached. The corn had been planted in a spiral formation about a tall post capped with a circular drum or cask.

  • This is the synmotor, the farming machine that does its work without an attendant; when it isn’t cultivating the farm it can be connected to a churn to make butter.

  • On the big drum the steering wire is wound, this drawing the cultivator ever closer to the center.

Close inspection reveals a thin wire extending to a central drum, around which the wire winds itself as the work of cultivating proceeds. That explains the spiral movement. The wire shortens itself by the same amount each trip around, and is used for steering the machine. Yes, it is machine, after all. The wire, being perfectly tempered, cannot stretoh, and an electro-coated surface protects it from rust. Its total weight is less than two pounds; yet a pull of six hundred pounds is required to break it.

The machine is a narrow tractor of special make, and it is called a “synmotor.” The engine is a compact but very efficient gasoline type of about four horsepower. To the framework can be attached any of the usual implements for cultivating the land. Plowing, hoeing, harrowing, and the any other operations are performed in the spiral path as well as in the straight course. A gang-bar, for the attachment of the implements may be used so that several rows may be cultivated at the same time.

When the synmotor is utilized on a large scale, the farm is divided into convenient ten-acre circles, each section being planted and cultivated separately. Any vacant spaces between adjacent circles can be utilized for fruit trees, buildings, or the like. For that matter, the intervening spaces can also be cultivated by merely disengaging the steering wire and utilizing the tractor in the customary manner.

For intensive farming and overlapping seasons, the accuracy of the synmotor in following a given track is of great advantage. The machine does not disturb the small plants, and it can work very closely to the rows. The working tools are spaced the exact distance between rows and do not swerve from the spiral course. Strawberries, peas and other vegetables can be cultivated with the synmotor,

With such a machine as this, the laziest man on earth can sit in the shade and fan himself while gasoline does his work.

  • Showing the works of the synmotor.

I’m sure this is an idea which has occured to many people – I’ve used it myself to compact gravel for a swimming pool. Here it turns up again in May 1960:

Tree Branches – and what to do with them

12 Jul

Speaking not of the days that are, but of the days that shall be … when we move out to Kirwee, we will have LOTS OF TREES.

I went looking for things to do with bits of tree. Herewith, several variations and a couple of nice ideas.

(1) Wood coasters:

(2) These coasters have felt pads underneath:

(3) Tree branch napkin rings:

(4) Tree branch magnets:

(5) A docking station for an iPod:

(6) More coasters, this time with numbers on them:

(7) Thank heavens, not more coasters. This time it’s cute little candle holders:



American hardiness zones – as they apply to New Zealand

10 Jul

American and British gardening books make frequent mention of climate zones. That’s all very well but I found it very hard to sort out which zone we live in, and the (colder) zone to which we’re moving soon.

This diagram, from the informative “Growing Gardens for Free” (2003)  by  Geoff Bryant, is actually the only place I’ve found that information:

(Nice to know I’m in zone 9, and will still be in zone 9 even as I move inland).