Lifeboat Farm

3D Printing Fly Traps
December 12, 2011, 3:18 pm
Filed under: 3D Printing, Garden, Technology

This is the third in what has turned into a three-part series on organic pest control (it’s just that time of year). The previous two posts were on organic wood lice control and white butterfly decoys.

Like most rural dwellers, we accept flies as part of life. Some years are worse than others but wet summers (like this one so far) seem to be very favourable to fly breeding.

We’ve had a few big fly traps over the years like the plastic lids you put on buckets and fill with bait. They work well, but can be a bit big and smelly to use too close to the house. I wanted to design a trap that was smaller, could be deployed nearer the house in larger numbers, and that used recycled materials if possible. It needed to be 3D printable and fit within the constraints of the build platform – 10x10x10cm.

After some messing about with various ideas, The bean can fly trap was born. In a nutshell, flies smell whatever bait and water you put in the can (a small piece of liver, or any offal works well), go in for a closer look, then find themselves trapped. They drown in the can and they in turn, become bait for more flies. The principle of fly behaviour the traps exploit is their drive to fly upwards to fresh air and light; they’ll just keep bumping up against the lid of the trap until they are exhausted and fall in the water.

The two parts of the trap are the lid that allows the flies to enter but not get out again, and a base that can be attached to the top of a fence post. Both parts friction-fit to the can. Most tin cans like this are the same dimensions the world over so it should work with almost any can.

Here are a few prototype traps in testing on top of one of our big traps. I played with various shapes and sizes of entry tunnels, and different vent slot sizes. Getting the flies into a trap was fairly easy if the bait was smelly enough. The harder part was keeping them in there. While we use wet bait to catch and kill the flies, I’ve heard from another user that they use dry bait to catch live flies to give to their pet frog. Either way, I’m happy with less flies in the world.

The plan now is to deploy these traps on fence posts all around the house to reduce the fly population through the Summer.



White butterfly decoys
December 8, 2011, 2:34 pm
Filed under: 3D Printing, Garden, Technology

The previous post about organic woodlice control touched on a couple of elements of pest control: trapping and physical separation of pest and plant. Another strategy that can work quite well is using environmental elements to confuse or deter pests. You can apply the principle to planting technique, by mixing up your plants to confuse pests (they don’t have to be too smart to find an acre of one crop). In this case I wanted to deter white butterflies from laying their eggs on our brassicas.

It turns out, white butterflies are quite territorial (or at least smart enough to know when to cut their losses). If a white butterfly sees other butterflies hovering around a target plant, they will move on to somewhere else to lay their eggs. You can use this behaviour to make decoy butterflies repellent to the real ones. People have used egg shells, white pebbles and even bread tags as decoys with mixed success.

My friend Vik had already created a model of a white butterfly and put it up on Thingiverse. All I had to do was download it and print one out.

While it was still hot from the printer I bent the wings up at a more realistic angle. A spare bit of filament melted and stuck to the bottom made a handy stalk to poke into the garden bed.

I printed a bunch (flock?) of butterflies and gave them some anatomical detail with a vivid marker before deploying them to the garden.

The stalks are quite flexible so the butterflies bob about in the wind. They look pretty realistic to me, but more importantly I’ve seen white butterflies hovering around, then leaving without touching down, all this week. Time will tell if any have the courage to sneak in to lay eggs.

If you don’t have a 3D printer, you could probably cut the same shape out of white plastic containers for much the same effect.

3D Printed coffee grinder part
December 6, 2011, 5:09 pm
Filed under: 3D Printing, Environment, Technology

My friend Eddie has a small coffee grinder that has given him many years of faithful service but a broken part has rendered it less useful than it could be. I’m not sure what the official term is, but I’ll call it the sweeper. It’s the part that sweeps the ground coffee out to the exit chute as it is ground. I thought I’d try to 3D print a replacement part.

3D Printing precision parts can be tricky as there are limitations when you are depositing layers of molten plastic on top of one another to make a part. Luckily, the most precise bit of this part is the brass hex bush, which I could re-use. I used the basic measurements of the broken sweeper to create a quick model in Google SketchUp. You can use any of the more complex (and expensive) design packages, but for 99% of the work I do, SketchUp works just fine (and it’s free).

Here’s the printed part, fresh off the Makerbot 3D Printer. It needs a few stray bits of filament trimmed, but otherwise ready to go.

Tidied up, with a quick sand and trim (you wouldn’t want any bits falling off into the coffee). The brass bush will just friction fit into the new sweeper.

And here’s the new sweeper installed and tested with some coffee grounds. The tolerance is pretty tight so as not to leave any coffee behind. I used ABS plastic for this print as it’s the most food-safe feedstock I have. It melts at 220 degrees Celsius so even if any bits do get into the coffee grounds, the extraction water wouldn’t be hot enough to melt it into the finished coffee.

And that’s it. One less appliance heading to the landfill for want of a single broken part. Best of all, now the part exists digitally, anyone who needs a spare can print their own. I’ll upload the part to Thingiverse on the off-chance someone else in the world needs one.

3D Printing replacement parts for a camera
June 30, 2011, 10:02 pm
Filed under: 3D Printing, Technology

My friend Eddie asked if I could print a replacement part for his old, but mostly useful Nikonos camera. Like so many consumer items we have, for the want of a single part or two, it could be almost as good as new. It needed a new knob to turn the film advance winder, and I noticed (after a web image search) it needed a new cover on the film winder assembly. Here’s the camera pre-repair:

The first thing I had to do was design the replacement part. After a quick measure I used Google Sketchup as a quick and easy tool for 3D design from scratch. This is how the film-advance knob looked after a couple of iterations.

Time to fire up the Makerbot and print out the part! I used PLA plastic for the first test prints, mainly because I have plenty of it, and it just happened to be in the machine at the time 🙂

First prototype parts hot off the printer:

After two quick test prints and a few refinements to the design, I printed the final parts in shiny black ABS and fitted them to the camera. The winder cover on the left is super-glued on and the film-advance is attached with epoxy for a more robust join.