Archive | November, 2012

Making wooden gears

29 Nov

I wanted some small wooden gears to decorate a steampunk costume. Nothing fancy, they don’t have to do anything.

Four different programs are needed to turn my idea into a chunk of machined wood:

The starting point is the very useful (and cheap) Gear Template Generator from, which lets you choose all sorts of parameters for your gear. If you just want to print it out on paper, then the web-based program is free, but I bought the program ($26) a couple of years ago and that lets me export out a .dxf file which my cad software can eat.

The .dxf files (one per gear size) get imported into the CAD (computer aided design) software. I use CAD X11, which is somewhat funky but does the job and is fairly cheap.

After that there’s yet another program, this time it’s a CAM (computer aided manufacturing) program, where I map the lines on the diagram into movements of the cutter. I use CAMBAM which does the job nicely.  I tell it “I want to cut around the inside of this triangle, with a cutter of X diameter, cutting at speed Y, in passes Z millimetres deep” and it turns it into the truly strange NC (numerical control) data format that many computer controlled machines use.

One last program, Mach 3, reads the NC file and wiggles the motors on the computer controlled cutter to make it follow the pattern I want.

  • Here’s the computer controlled cutter, with a piece of 3mm MDF (fake wood) clamped in place to cut some mounting holes.

  • Measuring the how high off the surface the cutter is, using a pack of cards and a vernier caliper. The wood is bolted down, now.

  • Many layers of sound-proofing are needed when the little trim-router gets going.

  • The Mach3 software steps through the hundreds of lines of  “go to …”, then “follow curve …”, “lift up by …” etc. You can see the pattern it has to cut at top right.

  • And after an hour (it’s a very slow machine), it’s cut out some gears and a generated a lot of sawdust. Time for the vacuum cleaner.

  • Fresh off the cutter the gears are pretty rough – with fuzzy edges and bits to remove.

  • A quick zap with the belt sander cleans them up nicely.

Questions about characters (writing fiction)

27 Nov

Some simple programming to help a neophyte writer

A quick search of the net found many lists of questions to ask about the characters in one’s story (for instance 100 Character Development Questions for Writers). A few minutes work netted me a bunch of questions like this:

  1. Who is an actor you can’t stand?
  2. What is your worst childhood memory?
  3. Where do you live now?
  4. What is this character’s greatest fear?
  5. Have you visited any interesting places for work?
  6. What is more important – sex or intimacy? Why?
  7. What makes your character laugh out loud?
  8. What are your grandparents’ names?
  9. What is the first historical event you remember? (The Great Depression, Kennedy’s assassination, the moon landing, September 11th)?
  10. When will you be able to retire?

I ran some tidy-up code over the list and ended up with 290 questions about characters. (At some stage I’ll add questions about places, events, and objects as well).

With my questions in hand, I whipped up a (very crude) storage format for the characters in my story. In this case it looked a bit like this:

Person:  Sarah, descr=Sister

Place: Sarah_Flat

Person: Mark

My next step was some code to read in the list of people, read in the list of questions, then randomly ask question A about character B (recording the answers for later review) and looping around asking more questions until I got tired of it.

  • Asking a question

This is all very simple stuff, but I was suprised by some of the answers that popped into my head as my computer interrogated me. At the end of a very short time (in between fixing dumb bugs in the program – as is often the case in the simplest of programs) I found I had some useful background developing around my characters. Well worth the time spent writing it, and it should be a good way to fill in the odd five or ten minutes of spare time.

30 minutes after sunset and five minutes from home

26 Nov
  • A still night and lights from Mount Pleasant reflecting on the water.

A particularly calm evening sent me out for a short drive to where I suspected there might be some nice reflections. I’ve often seen these lights reflecting when I’m on the way home so I guessed they’d make a good show. I’ve rather taken to the lighting effects when there’s still a bit of light in the sky, rather than inky blackness, with 20 second exposures which makes for nice effects on the water. You can’t see them but there were actually swans swimming to and fro through the streams of light.

  • 20 second exposure, F/11, ISO 800

  • Still 20 seconds, but stopped down to F/14 which makes the background darker.

  • And a view the other way at an industrial plant.

A hole and a show

24 Nov

Progress on the new house.

  • It’s just a hole in the ground. But it’s the FIRST hole for the new shed and house.

  • Cleared area for the 81 square metres of shed.

  • There’s a row of holes for the posts that frame the building.

The one hundred and thirty seventh Courtney A & P (agricultural and pastoral) show.

  • Lots of people, lots of farm animals, lots of vintage tractors.

  • More people, more farm animals, and lots of carnival operators making a living.

Chasing an alien thing through the ice caves

23 Nov
  • It’s getting away!  (larger version on YouTube)

I’ve been spending huge amounts of time studying Blender over the last few weeks. It’s insanely powerful, great fun, and excellent value for money (it’s free). However, it’s got so many functions and so many things you can tweak, that it takes a lot of learning.

This was a fun little exercise, an animation of chasing a blobby alien thing through caves. It took about a day to get my head around 10 seconds of animation, and 45 minutes to render it.

  • From the outside, the cave system looks like this:

  • Both the blobby thing and the camera are following along a three-dimensional path through the caves, a constant distance apart.

  • A larger image, showing a bit more detail.

Grey Goo in the 1960s

17 Nov
  • “As soon as each box was activated, it began to roll about on the table on its little casters, avoiding collision with its fellows.”

Back in the 1970s, I read a rather strange novel by John Sladek – “The Reproductive System” (1968).  A researcher, Calvin Potter, helps build a self-replicating robot system. The project was set up by “Wompler’s Walking Babies” as a way to get government money when sales of the dolls died away. Other than a difference in scale (the individual units are inches across) the plot concerns the “grey goo” problem encountered in modern discussions of nanotechnology, although in a rather surreal way. The researcher wasn’t particularly competent – he only got the job because the application form didn’t have room for “Miami Institute of Technocracy” so he had to put down “M.I.T.“, but then no-one else really seemed to know what they were doing either.

At each exhibit, Grandison would pause while Cal named the piece of equipment. Then he would repeat the name softly, with a kind of wonder, nod sagely, and move on. Cal was strongly reminded of the way some people look at modern art exhibitions, where the labels become more important to them than the objects. He found himself making up elaborate names.
“And this, you’ll note, is the Mondriaan Modular Mnemonicon.”
“—onicon, yes.”
“And the Empyrean diffractosphere.”
“—sphere. Mn. I see.”
Nothing surprised Grandison, for he was looking at nothing. Cal became wilder. Pointing to Hita’s desk, he said, “The chiarascuro thermocouple.”
“Couple? Looks like only one, to me. Interesting, though.”
A briar pipe became a “zygotic pipette,” the glass ashtray a “Piltdown retort,” and the lamp a “phase-conditioned Aeolian.” Paperclips became “nuances.”
“Nuances, I see. Very fine. What’s that thing, now?”
He pointed to an oscilloscope. Cal took a deep breath.
“Its full name,” he said, “is the Praetorian eschatalogical morphomorphic tangram, Endymion-type, but we usually just call it a ramification.”
The old man fixed him with a stern black eye. “Are you trying to be funny or something? I mean, I may not be a smart-aleck scientist, but I sure as hell know a television when I see one.”
Cal assured him it was not a television, and proved it by switching it on. “See,” he said, pointing to a pattern of square waves, “there are the little anapests.”

It was an array of gray metal boxes, each about the size of a cigarette package, stacked loosely together in a cube about two feet high. When the toggle switch, prominent on the top of any one box was thrown, it sent out a tuned starting signal to the rest; they were switched off in the same way.
As soon as each box was activated, it began to roll about on the table on its little casters, avoiding collision with its fellows. When all the boxes were moving, they resembled a complicated Brownian movement on the dark  surface of the table, as they explored every inch of it.
Kurt and Karl placed bits and scraps of metal on the table. The smaller bits were at once devoured by individual  boxes, but the larger bars attracted the entire brood. The gray packages, now the size of king-size cigarette cases, swarmed over them like ants, gouging away with tiny cutters and torches — and growing fatter.
It made Cal shiver to look at their orderly feeding.

NOTE: The animated gif at the top of the page was an attempt to illustrate the little grey boxes swarming. It took me a ridiculous amount of time to create – using Blender and Gimp – but I learned a whole bunch of new techniques. Unfortunately, I couldn’t get the ‘Boids‘ functions working properly in Blender. My attempts had impressive flocks of hundreds of little machines, but I couldn’t get them to respect each other’s physical space. Sigh.

After Sunset

11 Nov
  • F13, 20 second exposure, ISO 800

Some more experiments with long exposures after sunset, but while there’s still light in the sky. I like the way the different coloured streetlights illuminate the hillside.

  • F5.6, 20 second exposure, ISO 800

  • F11, 20 second exposure, ISO 800

  • F9, 20 second exposure, ISO 800

  • F11, 20 second exposure, ISO 800