Mud bricks





Simplified blower and furnace experiments

Blower description


Firstly, the impellor was simply a stick as a rotor with a 40 cm wide rectangle of bark tied into a split in its end with a bark fibre cordage. A stone with a pit carved into it acted as a socket for the lower half of the rotor to spin in. If spun in the dirt the rotor can drill down and the position of the impellor can reach ground level causing the blades to bump into rocks and dirt. Later, I plastered the stone socket into the ground with mud to hold it securely in position (not shown in the video, just be aware of this solution if the socket shifts around too much).

Secondly, the housing for the blower was made in situ of ordinary mud (dirt and water on site). It was a bit more than 40 cm in internal diameter. The walls of the housing were solid mud and the roof was made of sticks covered with mud. An opening more than half the length of the impellor was left in the roof to remove the impellor for maintenance and to admit air into the blower during operation. In use, the portion of this opening near the front of the blower was covered with a tile. If left opened the blower still worked but covering it improved performance by preventing air escaping near the front. In places where water is not available, a housing shaped pit covered with sticks and dirt might work instead.

Finally, a simple length of cordage was used to drive the rotation of the impellor. This cord was placed in a notch carved into the top of the impellor rotor. The cord was wrapped around the rotor about 2.5 times. During operation the cords were pulled outwards causing the rotation. When fully unwound, the momentum of the impellor then wrapped the cord back around in the other direction. Then the cords were pulled outwards again causing the impellor to spin in the other direction. Note that this is a centrifugal blower with a symmetrical housing, therefore it doesn’t matter whether the fan spins one way or the other (clockwise or anti clockwise), the blower will always suck air in to its open top and force it into the furnace.

This design is easy to make and use. It can be made with minimal materials by unskilled people. The impellor design is simple yet effective. A stick, some bark and lashing of some sort should be available in most areas. The housing being made from mud, is easily sourced also. For the drive mechanism, I chose this method because the first blower I built had too many parts. There was a frame made of wood and vine to hold the rotor in place which kept causing issues with the rotor seizing or jumping out of the socket. Also, the bow that was used to drive the rotor added unnecessary complexity. In the new design, the simple cord in the notch of the rotor did away with the frame and the bow of the old design and the associated difficulties.

Furnace experiments

The blower was used to power a furnace attached to the front of it. Note that with minimal materials, the blower could simply force air into a hole in the base of the furnace and work satisfactorily. But I wanted to test a different configuration so I used clay grate from a previous kiln I made. Fuel in the form of wood and charcoal was used in this furnace by being placed on top of the grate instead of under it. During operation, the blower forced air up through the grate into the burning fuel bed increasing the rate of heat production relative to the use of natural draft (convection) alone.

I made 3 pots and fired them with charcoal. The first pot was painted with iron bacteria (iron oxide being the active ingredient). When fired, the oxide melted slightly showing minimal glazing. The clay became quite hard, possibly stoneware. The second pot was painted with wood ash and placed on a three sided clay plinth to hold the pot in the position of highest temperature in the fuel bed. The pot softened and sagged apart catastrophically. But the ash glaze gave a dark green smooth finish (difficult to see in the video). Finally, a pot was place upside down on the grate and a cylindrical brick made of iron bacteria, charcoal powder and wood ash was put on top of this. The brick melted over the pot, covering it in a viscous blob of slag rather than a thin glaze. On inspection, the slag had 1 mm sized spheres of metallic iron in it. Some of these were picked out and stored in a pot. The reason for these experiments like these to gain knowledge that might be of practical use in future projects that have not yet been determined.





Reusable Charcoal Mound







Water Powered Hammer (Monjolo)







Termite clay kiln and pottery







Planting Cassava and Yams

In this video I build a garden to grow Cassava and yams, two staple food crops. Cassava is a shrub that develops large edible roots. Yams are a climbing vine that produce large, edible underground bulbs and smaller aerial bulbs on their vines.

I had 5 huts, but the wattle and daub hut (from the first video uploaded on this channel nearly 2 years ago) became dilapidated. I abandoned it in favour of the other huts I built and neglected the roof. This let water in destroying a wall. Also, the sweet potato patch behind it had a tree fall across it destroying the fence. So I demolished them both to make one large garden.

After removing the fence I set a fire under the fallen tree to burn it in half rather than spend the effort of cutting it with stone tools. After burning almost all the way through, it rained. So I came back later and cut through the rest of the log with stone tools. I eventually broke the tree in half. Using smaller logs as levers I moved the tree out of the garden clearing the space for the garden.

I then collected wood and built a simple fence that was woven loosely together with vine. The fence needs only to discourage large animals from entering to prevent them causing damage. Most times pigs and wallabies don’t know that food in growing in the garden and won’t try and enter if they see no reason to. Or at least that worked for the sweet potatoes so we’ll see if it works this time.

For the yam and cassava planting material I travelled far down stream to the site of my old stone hut that I built over 10 years ago. It had a corbelled dome roof that was damaged when a tree fell on it during a cyclone and it came down a few months later. The thick walls however have stayed standing for about a decade though.

Yams and cassava grew wild at this site which is one of the reasons I built the stone hut there. These plants are not native to Australia but grow wild here after having escaped from people’s gardens (similar to how wild pigs live here now after escaping from farms). The planting material for the yams are the bulbs that grow on the vines. The planting material for cassava are simply 25 cm long pieces of stem.

On returning to the garden, a scrub turkey was seen digging in the mounds. Protected by law, this bird has lost its fear of humans and in this case I’ve semi-domesticated it. Originally it was attracted to soil I dug up for the worms it exposed. I started leaving a pot out with small sweet potatoes in it for it to eat and now it investigates any pottery I leave for food. Now it my visits my projects and will only leave if bored or chased away. I suppose this is similar to how chickens were domesticated, in fact bush turkeys and chickens are related and will produce hybrid offspring.

Unfortunately, it has learned that the garden contains food. Originally, I was only going to plant yams but I saw the turkey digging them up and eating them. So, I planted cassava in the mounds so that the turkey would be discouraged by finding only wooden stems to peck at. I secretly planted the yams along the fence of the garden because the turkey only thinks the mounds contain yams. They can’t smell very well and only find food by sight and learned behaviour.

I planted the cassava in mounds 1 meter apart by pushing them flat into the soil. I planted the yams at intervals along the fence so they could use it as a trellis. 32 cassava stems and 12 yams were planted. Then a storm began and watered the garden. In less than a week the cassava had sprouted shoots and began to grow. The yams will take longer as I planted them deeper.

Cassava produces the most calories per time and space of any plant apart from sugar cane and sugar beet. But it requires much less fertiliser and effort. A hectare of cassava produces enough calories in 2 days to sustain a person for 1 year. It takes a year to come to harvest but will stay in the ground for a year without becoming woody. The tubers are high in starch and are what tapioca is made from.

This variety is called sweet cassava (actually not bitter cassava, it doesn’t taste sweet but starchy instead) and it needs to be boiled for 20 minutes to get rid of some cyanide it contains. The bitter variety contains such high levels that it kills if eaten raw and requires more extensive treatment to eat. There isn’t much nutrition in cassava other than the large amount calories it contains so other food would be required to provide protein and nutrients.

After I harvest the cassava I planted I’ll try fermenting it (which adds nutrition), drying it and pounding it into flour to make flat bread. Cassava flour has the same energy content as wheat flour, stores well and tastes somewhat similar. Or I could just cook it and eat it straight from the garden. I’ll use the yams like potatoes when they’re ready.

Bed Shed

I built a bed shed, a small shelter with a sleeping platform built into it. It’s quicker to build than a large hut but can be extended later on when materials and time become available. It’s not far from the dome shaped grass hut I built earlier.
The hut is 2 m long and 1 m wide. Four posts were hammered into the ground, two 1 m high posts (1.25 m long, 25 cm underground) on the low side and two 2m high posts (2.25m long, 25cm underground) on the high side. Onto this, a sloping rafters was lashed on with fish tail wait-a-while, a spiky palm with a vine like habit. To remove the needle like spikes from the plant, the leaves are pulled off so that the frond sheaths come with them. This made suitable lashings.
Battens were then tied to the rafters and bundles of long grass from the mountainside were collected. Using vine from the bush, the bundles were lashed to the battens starting at the low side and continuing to the top so that the grass would shed rain. Cross bars were lashed to the frame of the shed at each end to support the bed. These were at a height of 1m above the ground.
The bed frame itself was made from four poles (two 2m long and two 75 cm long) lashed together to form a rectangle 1.75m long and 75 cm wide (the ends of the two longer poles extending further to sit on the cross bars in the shed). Lawyer cane was then wrapped length ways over the frame to create horizontal threads. Then more lawyer cane was woven between these threads to form a sort of bed spring net. The bed frame was then put on the cross bars and tested to see if it could hold my weight. A mat I made from woven bark in a previous video was used for bedding and a bunch of grass for a pillow. In a rainstorm it was possible to make a fire in the space under the bed.
This structure is quick and easy to build. The bed is 1 m above the ground and provides plenty of area beneath to store fire wood and tools out of the rain as well as a place to sit and make things. The bed is comfortable and keeps the occupant off the ground away from ground dwelling creatures at night. The smoke coming up from the fire keeps mosquitoes away while providing heat and light reflected back from the roof. In fine weather the fire can be placed in front of the shed in the open while during rain the fire can be kept under the shelter to keep it dry. If room is needed to stand up the bed can be folded up against the roof and tied to it using cordage.
This shed is literally one half of the standard rectilinear hut I usually build (2m x2m floor plan, 2m tall ridge line and 1 m high side walls e.g. from wattle and daub hut and tiled hut videos) and was built to be upgradeable. Later, the other side of the roof could be added on and then walls of some kind built around the frame to form a full hut.

Fresh water Prawn Trap



Spear Thrower




