Primitive Technology: One Way Spinning, Rope Stick Blower
The current blower design Inside the blower Notice that the fan spins clockwise and anticlockwise intermittently with a pause in between Though an effective method, energy is lost when the rotation is halted and reversed. Also, the housing needs to be symmetrical rather than volute shaped to work. Off to test an idea Cutting 2 wooden stakes 1 m long (4 x my foot) 2 x 1m stakes Cutting a stick Debarking 50 cm long stick Fire sharpening both ends of the stick Fire sharpening one end of each stake Fire sharpened wood Iron knife from a previous episode Drilling a hole 50 cm from the top of the stake Same with the other stake Using the rotor to drill the bearing holes in the stakes Hammering the stakes in 50 cm apart, 25 cm deep Inserting the rotor ends into the bearings Testing that the rotor turns freely without falling out There's a tree here with fibrous bark that drops its branches in the wet season The bark can be easily stripped off if it's rotted a bit in the rain The bark The bark is put in water to soften overnight The next day it is taken out and is pulled apart into thin strips The fibrous inner bark is separated from the stiffer outer bark Bark fiber strips To make rope, a bunch of strips are twisted in the middle to get started Then one strand is twisted clockwise before being twisted over the other one anticlockwise, the process being continuously repeated The strips will not come apart after this More strips can be added in for a long continuous rope Getting wood for the fan spokes Cutting wood to 25 cm length (my foot length) Splitting wood with stone wedge Lashing split wood together at one end with bark fiber strip Wedging spoke onto and around the rotor then lashing the other end closed Another spoke is added at right angles to the first The rope is attached to the end of a 75 cm long stick The rope is wrapped once around the rotor with the stick underneath and is spun a few times to loosen the bearings The technique used here is producing one way, continuous rotation. Let's take a closer look First the stick is pulled down and back causing the rotor to spin clockwise.
Then it is lifted up and forward, loosening the rope to conserve clockwise momentum The cycle is repeated producing continuous, one way rotation Note how the rotor continues to spin unimpeded in one direction when the rope is loosened Collecting leaves to form the fan blades The leaf is folded in three so it is 7.5 cm long (ring finger length). Then it is folded in half length ways It is then cut with a stone so it is 6.25 cm wide (bit longer than 2 finger joints) The leaf rectangle is then inserted into the spoke Leaf fan An old broken blower housing is used to test the fan The aproximate position for the housing in relation to the rotor bearings is found Mud is placed on the ground to form a secure seat to hold the blower housing upright The housing is placed on the mud The rotor is placed in the bearings The fan spins without hitting the walls of the housing The rotor is put through the hole in the lid, the lid held in place against the housing with mud and the rotor placed back into the bearings The blower is tested on some leaves Making fire with fire sticks Blowing the ember into flames with the blower Another feature of this design is that it leaves one hand free to add fuel and tend the fire without stopping Adding a tuyere to the blower to concentrate the air blast Making a furnace from mud to contain the fire The blower works well attached to a furnace Collecting clay to make a blower housing specifically designed for a one way spinning fan Digging clay processing pits Compacting lower sedimentation pit Raw clay is dumped in the upper slaking pit and water is added The clay is dissolved into solution and then allowed to run into the sedimentation pit leaving the rocks and stones in the slaking pit The purified clay settles in the sedimentation pit It is collected in a pot while still wet And is placed on sand to dry quicker The moisture wicks into the sand and the clay stiffens. The uniform sized sand that gets into the clay will act as grog, preventing cracks as it dries. Ash is dusted onto a flat surface to stop clay sticking Clay is formed on this surface to form a disc 40 cm in diameter (using a stick measured against a foot, 25 cm and subtracting 2 finger joints, 5 cm to form a 20 cm radius) A 25 cm circle is scribed in the middle where the fan will go Because the fan rotates in one direction only, a volute shaped housing can be designed that will better direct air At one point, mark 3/4 the distance from the fan to the edge At 90 degrees around the circle, mark 1/2 the distance from the fan to the edge At another 90 degrees around the circle mark 1/4 the distance from the fan to the edge Scribe a spiral back around connecting all these points. At 0 degrees the line starts at the fan edge and at 360 degrees the line touches the outer circle To form the slabs for the walls of the housing, a rectangular mold was made from split cane and clay pressed into it The slabs are then taken out and pressed onto the disc to form the walls following the line of the spiral Leaving a triangle of clay to support the spout, the excess clay is then cut away from the housing To form the spout a log is dusted and clay formed around it making a pipe The spout is then pressed onto the housing where the air exits, its angle adjusted by putting sticks under the log The log is also turned to ensure the clay is not sticking to it, making it easier to remove later The 6.25 cm (1/4 my foot) air inlet for the housing is cut in the center More slabs are added to build the walls up to a total 10 cm tall (4 finger joints high) Clay is added over the spout to make a good seal with the lid (yet to be made) The log is removed when the spout has stiffened Housing complete Making sure fan fits Turning the housing when stiff enough to Trimming clay, neatening up To form the lid another 40 cm disc is made The housing is lifted and pressed onto the wet disc to form a tight fit Excess clay is trimmed from the disc to match the housing profile A stick is used to mark a circular hole in the lid matching the hole in the housing The housing is lifted off the lid The marked hole is cut out and neatened up Housing and lid completed Fire was used to speed up the drying process Using mud to form a seat for the housing Housing put in place Fan rotor in place Rope stick test Bricks made in previous episodes are used to build a furnace Building the square furnace pit with 4 bricks The next layer has a half brick to leave an opening for the tuyere Mud to hold the tuyere Tuyere in place Sealing it in Putting in a floor of mud Putting the lid in place The lid turns till it matches the housing profile and is held in place with mud at the base Clay is used to seal the lid to stop air leaks Hot coals into the furnace Testing the furnace Adding another layer to the furnace Close up of the one way spinning technique One way spinning, rope stick blower
2024-02-04 21:31
