GB2525400A

GB2525400A - Products and the apparatus for their manufacture and transportation

Info

Publication number: GB2525400A
Application number: GB1407109.6A
Authority: GB
Inventors: Senake Atureliya
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-04-22
Filing date: 2014-04-22
Publication date: 2015-10-28
Also published as: GB201407109D0

Abstract

A 3D printing mechanism comprising a planar build surface 15 that rotates in relation to a multiplicity of print heads where each head as a multiplicity of nozzles 2. The nozzles are preferably moveable to allow layers of material to be built up; and may extrude thermally or chemically solidifiable material and clay in the form of spiral tubes or beads that lay on top of each other and interlock to form a spherical structure that floats and can be used a residential building; the nozzles can also apply a waterproof membrane or glaze. The extruded bead may have a cavity to provide buoyancy to the building. The nozzles may be attached to a framework that has robotic arms attached that place components such as electrical circuits, doors and window frames onto the planar surface or into the 3D object that is being printed. The nozzles may be feed by augers and have means to heat the material to be extruded if required; one of the augers may be supplied by raw material that is drilled from the manufacturing site, which is preferable located alongside or on a watercourse. Alternatively the framework may be rotated around the planar building surface.

Description

Products and the apparatus for their manufacture and transportation

Summary of invention

[0001] This invention describes fused deposition modelling printers that address some of the problems associated with the technique including slow print speeds and the inability to manufacture complex products that include different materials and prefabricated components. It also describes manufacturing units based around the printers that can be used to produce building with numerous environmental and cost benefits by turning the costly process of dredging into clay mining for value added product manufacturing.

Technical Problem [0002] Many 3D printers are limited by low print speeds and flexibility. For the technology to compete with production line manufacturing it is necessary for printers to be able to produce finished items that comprise of a variety of different materials and components at a speed that is acceptable to consumers. This does not have to be as high as that achieved by a combination of plastic injection moulding machines and high speed manufacturing lines as each domestic 3D printer is likely to supply a few consumers.

[0003] Another problem is that because fused deposition printers need to deposit material onto a surface or on top of either the build surface or a previously deposited layer of material because gravity causes the molten material extruded from a printing nozzle to fall before it can solidify. For this reason temporary support material which needs to be removed by post processing is currently used to produce parts with overhangs.

[0004] Attempts to use 3D printers to produce building have addressed labour but not raw materials or transportation costs. Environmental factors such as resilience to deteriorating conditions and the minimisation of impacts have not been addressed.

Solution to Problem [0005] According to one aspect of this invention there is a printer based around a framework upon which a multiplicity of extrusion nozzles and articulated robot arms are mounted. In this invention the generic term robot arm'is used to describe pick and place mechanisms of all types that are in the public domain. This framework and a build surface upon which objects are constructed are connected by a mechanism that allows them to move rotationally and linearly with respect to each other.

[0006] In a preferred embodiment of this invention the build surface both rotates and moves vertically allowing the framework to remains stationary simplifying the means by which raw material and components are fed to the extrusion nozzles and robot arms.

[0007] In a preferred embodiment of this invention where the object being manufactured is large or heavy it is the framework that rotates over the build surface.

[0008] Advantageously the extrusion nozzles and robot arms are individually mounted upon carriages that can be used to position each at a set distance from the centre of rotation.

[0009] As there are a number of proven guide and driving mechanisms that can be used to achieve the described motion these will not be elaborated upon in this description. Some examples of guidance mechanisms are slideways along which either frictional or roller bearings run. Driving mechanisms can be electric motors or pneumatic or hydraulically driven cylinders. Rotational movement can be turned into linear movement using ballscrews or leadscrews.

[0010] In another embodiment of this invention the 3D printer is made up of a multiplicity of nozzles and robot arms that are each mounted on one end of a tube or rods that have their other end attached to a pivot that itself is fixed to around the circumference of a central tube or rod. As the tubes pivot the nozzles and robot arm mount points are swept along a semicircular path that is in the same plane as the central tube or rod.

[0011] Advantageously the central tube or rod is mounted in such a way that it can rotate about its own axis so that it can also guide the nozzles and robot arm mountings in a circular path that is perpendicular to its axis. In this way if the material could be made to turn solid as it emerged from the nozzle or if a means was provided to support it then a single nozzle could extrude a bead or tube of material in a spiral path to form all or part of a sphere.

[0012] In a preferred arrangement of this invention a multiplicity of nozzles would all extrude spiral tubes or beads of material on top of each other that interlock to form all or part of a sphere to increase overall print speed.

[0013] Advantageously the nozzles could extrude materials with different properties or colours.

[0014] Advantageously the tubes to which the nozzles were attached could be of different lengths so that the multiple spheres were printed one inside the other to create cavity walls for insulation or air pockets for buoyancy.

[0015] Advantageously the pivot angles of some tubes could be greater than that of others so that nozzle printing higher than other following nozzles could print a surface such as a waterproof membrane or glaze onto which lower nozzles could subsequently deposit material such as clay.

[0016] Advantageously the central tube or rod would also be able to move along its own axis to allow the nozzles and robot arm based to print cylindrical profiles of various diameters as well as spherical ones.

[0017] Advantageously the central tube and other tubes that feed specific nozzles could house augers to feed raw material to the nozzles.

[0018] In a preferred arrangement of this invention where a tube as opposed to a bead of material is being extruded the nozzle incorporates a shaping component in its mouth to create the void in the centre of the extruded tube.

[0019] According to one embodiment of this invention where heat needs to be applied to a bead or tube of semisolid or liquid material being extruded to solidify it then the nozzle will incorporate a chamber through which the extruded material passes that is heated directly or indirectly using hot air.

[0020] In a preferred arrangement of this invention where a tube as opposed to a bead of semisolid or liquid material is being extruded that needs the application of heat to solidify it then a baffle will be attached to the end of the shaping component so that a chamber into which heat can be applied is formed between the baffle and shaping component and walls of the tube.

[0021] According to another embodiment of this invention where heat needs to be applied to a bead or tube of semisolid or liquid material being extruded to solidify it and the material being extruded had an adequate electrical conductivity and resistance because of its mineral and moisture content then the nozzle could incorporate electrodes through which electrical current could be passed to locally heat the extruded material to solidify it.

[0022] Advantageously where the 3D printer is installed in a floating building manufacturing facility the central tube auger can be connected to a drill that mines the bed of the watercourse to supply clay to the nozzles.

[0023] In an alternative arrangement of this invention the tubes onto which the nozzles and robot arms are mounted have their pivoting ends fixed to a ring that can move along the central tube or rod rather than directly to the tube or rod itself.

[0024] In a preferred arrangement of this invention the build surface would be surrounded by cartridges that store prefabricated components or end effectors that can be accessed by the robot arms.

[0025] Advantageously the 3D printer and optionally component dispensers would be mounted in gimbals to allow it to be accurately rotated and positioned in three dimensions so that previously printed material or the build surface was below new material being printed. This would help eliminate the need to deposit and remove support material when printing an object with overhangs.

[0026] According to another embodiment of this invention the objects being printed would be floatable so that they could be constructed in a location adjacent to sources of the main raw materials required in their construction and then be floated along watercourses to installation or storage or land transport locations.

[0027] In a preferred arrangement of this invention the raw material is clay or sand and a multiplicity of 3D printers as described in this invention would be incorporated into a manufacturing facility that would either be located adjacent to or float upon a watercourse from which clay or sand could be dredged or mined and the objects being printed would be residential or commercial or industrial building or their components thereof.

[0028] Advantageously the floating buildings could be tethered to the base of a watercourse in such a way that the wave or tidal movement of the water causes the tethers to turn generators to generate electricity or compress air or create other forms of energy.

[0029] Advantageously by constructing the buildings so that they can float they would be more waterproof than most existing buildings and therefore more suitable for installation on flood plains. Longer term if the installation locations became less habitable or desirable then the owners of homes could float them off to better location rather than just selling or abandoning them.

[0030] In a preferred arrangement of this invention layers or tubes of clay would be printed onto layers of waterpioofing and strengthening and insulating materials or components.

[0031] [0032] Advantageously other functional components such as doors and windows and plumbing and electrical curcuits would be placed into the printed object by the robot arms as the object was printed.

[0033] Advantageously the robot arms would pick the components from dispensing units.

[0034] Advantageously other components such as roof beams or structural steelwork would also be printed separately to the object by 3D printers or robot arms equipped with 3D printing nozzles in the vicinity ready for picking and placing into the object.

[0035] Advantageously a land based manufacturing unit would incorporate a dry dock be located adjacent to a tidal watercourse. The dry dock would comprise of a build area surface surrounded by a multiplicity of waterproof walls and gates. When the printed object was ready to be despatched the dry dock would be flooded at high tide and the gates opened so that the printed object could be floated off the build surface and into the watercourse.

[0036] Advantageously a floating manufacturing unit would incorporate buoyancy tanks. When a printed object was ready to be floated out into the watercourse then air could be expelled from the tanks to lower the manufacturing unit and build surface into the water so that the printed object can be floated off it and out into the watercourse.

[0037] In a preferred arrangement of this invention a floating manufacturing facility would incorporate the means to dredge or mine and filter and prepare the clay or sand from the ground beneath the watercourse so that it can be fed to the 3D printing nozzles.

[0038] In one embodiment of this invention the mechanism for dredging the clay from beneath the watercourse would be a multiplicity of bucket conveyors.

[0039] In another embodiment of this invention the mechanism for mining clay from the ground beneath the watercourse is a drill.

[0040] Advantageously the drill would be connected to an auger to transport the mined clay up to the to the manufacturing unit.

[0041] Advantageously when all of the easily accessible raw material in one dredging location has been extracted a floating manufacturing vessel could simply be moved to another location with more accessible raw material.

[0042] Advantageously an initial non stick layer would either be laid over or printed on the build surface.

[0043] In a preferred arrangement of this invention the non stick layer would comprise of loose material such as sand or soil is deposited over the build su ri a ce.

[0044] In an alternative arrangement of this invention a combined waterproof and non stick layer would comprise of a sheet of flexible material such as plastic that would be rolled out to cover the area to be printed.

[0045] According to one embodiment of this invention a multiplicity of strengthening frameworks or layers of material are placed or printed between the layers of clay or insulating material.

[0046] Where the printed buildings need to be transported through calm waters such as inland rivers or canals they will advantageously be constructed on a flat surface and therefore end up with a flat base to maximise the floor area.

[0047] Where the constructed buildings need to be transported through more turbulent waters such as those found in the sea the buildings will be constructed with a convex base so that the building moves through the water as opposed to on top of it.

[0048] Advantageously to minimise the energy that would need to be expended by tug boats to push or pull a multiplicity of similarly sized and shaped buildings from one location to another the buildings would be constructed with a rectangular shape and would be closely coupled together to create as small a frontal area as possible that needed to part the water that the buildings were moving through.

[0049] Advantageously if buildings would be constructed with a spherical or ovoidal or cylindrical shape to allow them to be rolled over land if required.

Being of significantly larger diameter than that of commercially available wheels and tyres the weight of the building would be spread over a much larger contact surface which would reduce the amount by which it would sink into the ground when being rolled over it.

[0050] Advantageously the door and window and other apertures in the shell of the building would be designed so that they could be sealed either by the doors or windows themselves or by temporary sealing plates to allow as much of the building to remain under water level as necessary for the building to float.

[0051] Advantageously if the building manufacturing facility were located adjacent to or floating on top of a watercourse then the tidal or wave energy could be harnessed to power the equipment and fire the clay to minimise energy costs and pollution.

[0052] Advantageously the thickness of the walls of the building could be printed more thinly on successively higher floors as load bearing requirements were reduced.

[0053] According to one embodiment of this invention building components such as the walls and ceiling of a room that could be stacked together to take up a lot less space that a completed building could be manufactured with inbuilt buoyancy to allow them to be floated down smaller waterways and be connected together at the installation location to form larger buildings.

Brief description of drawings

[0054] The invention will now be explained by way of a series of illustrations.

[0055] Figure 1 is an isometric view of a 3D printer that incorporates a material filament extruder that is more fully detailed in figure 16.

[0056] Figure 2 is a top view of a similar 3D printer to that shown in figure 1 but with the extruder excluded to show the arrangement of the multiple print heads as well as the subcomponent pick and place mechanisms.

[0057] Figure 3 is a side view of a similar 3D printer to that shown in figure 2 mounted in gimbals so that it can be rotated about all three perpendicular axes by suitably positioned actuators.

[0058] Figure 4 is a cutaway illustration showing the construction and arrangement of components in a building that can be constructed using the machines described in figures 1 to 3 so that it has the required strength and buoyancy required to be transported from one location to another either floating in water or being rolled over solid ground.

[0059] Figure 5 is a cutaway illustration showing an appropriately sized version of the 3D printer installed in a waterside dry dock manufacturing facility extruding material and placing prefabricated components to manufacture a traditional cuboid shaped building.

[0060] Figure 6 shows the completed cuboid shaped building which having been floated out of the dry dock the adjacent watercourse at high tide is now being towed to another location.

[0061] Figure 7 is a cutaway illustration showing an appropriately sized version of the 3D printer installed in a floating dredging and manufacturing vessel extruding material and placing prefabricated components to manufacture a building.

[0062] Figure 8 is a cutaway illustration and Figure 9 is a cross sectional view of a floating vessel with a different design of 3D printer that is suited to producing spherical or ovoidal buildings or building components. The printer also incorporates the means to drill for clay under water and transport it by auger to the print nozzles.

[0063] Figure 10 shows a spherical buildings being winched out of an adjacent watercourse and rolled over the land to an installation location. This approach to overland transportation addresses the problem of the building sinking into ground as its weight is distributed through a much larger surface area than if it were being transported by conventional wheeled transport.

[0064] Figure 11 shows a building floating in a watercourse harnessing energy from tidal or wave motion.

[0065] Figure 12 shows a design of building component in the form of a set of outer inter connectable shells may be nested together for transportation and storage.

[0066] Figure 13 shows how a multiplicity of sets of the shells may be towed through a watercourse between locations.

[0067] Figure 14 shows how the shells may be assembled to create a building.

[0068] Figure 15 shows a print head that both extrudes a tube of semi solid material such as clay and simultaneously applies heat inside the tube to fire or harden it.

[0069] Figure 16 is a cutaway illustration of a compact mechanism for feeding multiple strands of material to print heads and processing stations.

[0070] Figure 17 shows two nozzle positions in cross sectional drawing of a building being printed out of square section tubes of clay.

[0071] Figure 18 shows whole sections of wall being printed by a swivelling print head that incorporates multiple nozzles.

[0072] Figures 1 and 2 depict two very similar variants of a combined 3D printer and assembly robot. The machine comprises of a frame 1 upon which there are a multiplicity of heated or cooled extrusion nozzles 2 and robot arms 3 mounted on carriages 4 that when powered by actuators can move along slides 5. In Figure 1 an extruder 6 is also shown mounted onto and above the frame 1. The frame 1 is itself mounted onto leadnuts or ballnuts 7 that move along leadscrews or ballscrews 8. Some extrusion nozzles 2 are fed with liquids or semi-liquid material such as clay from a pressurised tank 9 via flexible pipes 10. In figure 1 the solid material from reels 11 is also shown pushed through tubes by the extruder 6 to other nozzles 2 which are sufficiently hot to turn it molten. In figure 2 the extruders are mounted above the nozzles on the carriages 4 and pull the materials from the reel 11 to push into the nozzles 2. The robot arms 4 pick and place components 12 to from a multiplicity of storage containers 13. The robot arms 4 also deposit and pick up the most appropriate end effector from a storage unit 14 to suit the component 12 that they are picking and placing.

The frame 1 is positioned above a build surface 15 which is mounted in a multiplicity of bearings 16 so that it can rotate. The leadscrews or ball screws 8 are also mounted in bearings 17 onto a casing or frame 18. A product 19 is manufactured from the material and components on the build surface 15. One possible arrangemet of the components that make up the extruder 6 is shown in Figure 16 below.

[0073] Figure 3 depicts a machine similar to those shown in figures 1 and 2 mounted in gimbals. The machine sits in bearings 21 that can move around a ring 20. The ring itself is mounted in bearings 22 that sit inside another ring 23 which itself is mounted on bearings 24 in a frame 25. This means that when the machine is printing an overhang the product 26 that it is assembling can be orientated so that the material is laid directly on top of existing material.

[0074] Figure 4 is a cutaway illustration depicting a building is made up of a waterproof sheet 27 onto which is printed or poured a layer of waterproof material 28 such as resin or concrete upon to which is printed or poured a multiplicity of layers of clay 29 into which a multiplicity of reinforcing frames 30 are placed. Doors 31 and windows 32 can be sealed by covers 33 to make them watertight. Inside the building can optionally be built with printed internal walls 34 and floors 35 or these can be fitted later at the installation location. The floors 35 and roof 36 are supported by beams 37 that are optionally reinforced by bars or frameworks 30. A multiplicity of wind turbines 38 and solar collectors 39 with mirrors 40 to concentrate the sunlight onto them can be installed on the roof 36 of the building. The wind turbine 38 depicted in the illustration has sails made up of netting 41 onto which are fitted flaps 42 that open up to let air flow through them in one direction but trap air flowing in the other direction. The solar collector 34 depicted is integrated into the mast of the wind turbine 33 and houses pipes 35 that carry water which when heated by the suns energy may then be used directly or turned into steam to drive an electricity generator.

[0075] Figure 5 is a cutaway diagram showing a dry dock in which buildings may be produced. It is made up of waterproof walls 43 and a roof 44 and gates located adjacent to a tidal watercourse 46. In the diagram the level of water in the watercourse 46 is above the level of the build surface 47 inside the dock but the gates 45 stop the water coming into dock. Inside the dry dock a building 48 is being built from a multiplicity of materials and components that include clay 49 that has been dredged from the river bed and a steel reinforcing framework 51 that has been printed by melting steel welding rods 52 and doors 53 and windows 54. Supporting beams 55 are also being printed by a multiplicity of printing nozzles ready for incorporation into the structure of the building to support the roof and floors of the building 48. To begin each build a sheet of waterproof material 56 is fed from the reel 57 to cover the build surface 47 inside the dry dock.

Loose material such as sand is deposited onto the waterproof sheet 56 as it is unrolled. A multiplicity of printing nozzles 59 are mounted on carriages that move along radial slides that form part of a circular gantry 60. The gantry 60 sits on wheels that can move around a circular track 58.

The radial movement of the carriages along the slides and the rotation of the gantry allow the nozzles 59 to be positioned in any location over a circular build area, Some nozzles 59 first coat the loose material with waterproof sealant before other nozzles 59 then extrude tubes or beads 65 of clay over the layer of waterproof sealant to create the walls and floors and roof and other design features of the building 48. These print heads are fed by clay pump 61 from a tank 62 that is topped up by a dredger 63 which recovers clay from the bed of the river or watercourse. A multiplicity of robot arms are also mounted on carriages that run along the slides in the gantry. The can be positioned to pick and place components such as windows and doors into the apertures within the house. In other areas of the dry dock industrial other print nozzles mounted on industrial robots or positioning systems 64 print out components such as reinforcing frameworks 51 and supporting beams 55. End effectors comprising of pneumatically or hydraulically or electrically actuated grippers or suction cups mounted on industrial robots or positioning systems pick and place components such as doors and windows and reinforcing frameworks into the building as it is printed out.

[0076] Figure 6 shows the dry dock at high tide with the completed building 48 being towed out of it and to its installation location by a tug boat.

[0077] Figure 7 shows a completed building 65 being floated out of a dry dock 66 which itself is floating into the river 67. The dry dock is designed to move around the river so that its dredging bucket conveyors 68 can mine clay from different parts of the river bed. By emptying air out of ballast tanks 69 the dry dock can lower itself into the water so that the building 65 can float off the build surface and be pulled out of the dry dock 66 by tugs 70.

[0078] Figures 8 and 9 depict a floating dry dock in the form of a ship with a different printing arrangement for producing cavity wall buildings 71 in the shape of a sphere or ovoid. The apparatus comprises of a telescopic drill 72 linked to an auger tube 73 that retrieves clay 74 from the bed of a watercourse 75 and feeds it up into a multiplicity of pivoted telescopic tubes 76 which incorporate an auger and which end in twin nozzles 77 that are aligned in the direction of travel of the arms so that they lay two tubes of clay on top of previously laid layers to create a cavity wall. The auger motor 78 and pivoted auger tubes are connected by cables to winches 79 mounted at the top of the build chamber. A gantry crane 80 also the top of the build chamber to move prefabricated components such as doors and windows from a storage area 81 to their required location within the building 71 as it is printed from clay 74. A multiplicity of adjustable guides 82 both provide a support for overhanging material to be printed onto when the lower half of the sphere is constructed and a support for the sphere itself during the course of the build. The vessel has ballast tanks 83 that may be filled or emptied with air to alter the level of the depth at which the ship sits in the water. When a building 71 is complete it may be floated out of the build area by opening the watertight doors 84 on the side of the ship and emptying the ballast tanks 83 to lower the ship in the water flooding the build area.

[0079] Figure 10 shows an spherical or ovoidal shaped building 85 similar to those shown being constructed in Figures 8 and 9 being moved to a land based installation location. It is being pulled out of a watercourse 86 by a multiplicity of winches 87 using cables 88. For minimum resistance the cables have rod eyes 89 which incorporate bearings that are fixed to two mounting points 90 on the building.

[0080] Figure 11 shows a floating building 91 installed in a tidal watercourse 92. It is tethered to fixing points 93 in the sea or riverbed by a multiplicity of ropes or chains or cables 94. The other end of the ropes or chains or cables 94 are wound around pulleys 95 that are connected to electrical generators via gearboxes so that when the tide rises the ropes or chains or cables 94 are pulled they turn the pulleys 95 which are coupled to generators via a gearbox to increase rotational speed that then produce electricity. When the tide falls the slack in the ropes or chains or cables 94 is taken up by rewinding the pulleys 95 using the generators as motors by feeding power to them.

[0081] Figures 12 and 13 and 14 depicts a number of different sized outer shells that can be stacked to create a building.

[0082] Figure 12 shows a set of four shells. A small shell 96 is nested inside a larger shell 97 which is nested in an even larger shell 98 which is nested inside the largest shell 99. Each of the shells shown has windows 100 and two connecting doorways 101. In addition the largest outer shells have doorways 102. To help make the shells buoyant so that they can be floated for transportation and to help insulate the buildings into which they are incorporated the shells walls have air pockets 103 built into the walls.

[0083] Figure 13 shows several sets of shells 104 tethered together being towed by a ship 105 from their place of manufacture to their installation or local distribution location.

[0084] Figure 14 shows the shells assembled as a multi-storey building. The ground floor is made up of four large shells 99 and the middle floor is made up of four medium size shells 98 whilst the top floor of the building is made up of smaller shells 97. The shells are connected by the doorways 101.

[0085] Figure 15 is a cutaway illustration showing a tube printing nozzle. A semisolid material such as clay 106 is drive down a tube 107 until it hits a separator 108 that is suspended in the centre of the tube by a multiplicity of supports 109. The clay is forced around the separator 108 to form a tube 110. Despite the clay tube effectively being sliced along its length by the supports 109 the cut edges of the clay tube 110 are forced back together as the cross sectional area of the space between the outer tube 107 and separator 108 reduces from the material feed end to the outlet 111 of the tube 107. Air that is hot enough to dry out and lire the material 106 is fed through the inlet 112 through the body and outlet 113 of the separator 108 into the inside of the formed tube to fire the material. A baffle 112 fixed to the end of the separator 108 keeps the hot air from escaping down the tube so that the heat is concentrated near the output of the nozzle to help fire the clay 106. By heating the clay tube from the inside very little of the air escapes into the atmosphere reducing both the amount of energy required and wasted when firing the clay. It also means that the outside if the clay tube remains malleable and tacky for a longer period to help it to adhere to materials on top of which it is laid eradicating or minimising the need for cement or any other adhesive.

[0086] Figure 16 is a cutaway illustration of a feed mechanism for multiple material filaments comprising of a block 113 that is suspended in the frame of a machine bya multiplicity of supports 114. A screw threaded rod runs through the centre of the block 113. A multiplicity of material filaments 116 are fed through holes 117 in the top of the block into a chamber 118 within it and back out through similar holes in the bottom of the block 113. As each filament 116 passes through the chamber 118 it is guided and held against the screw threaded rod 115 by a pulley 119. The pulley is mounted in a clevis 120 mounted on the end of a linear actuator 121. The screw threaded rod 115 is mounted in bearings and driven by a rotary actuator. When the screw threaded rod 115 is turning and a filament 116 is forced against it by its pulley 119 it will be driven in the direction of the axis of the rod 115. Depending upon the direction of rotation of the threaded rod the filements will either be driven inward from the holes in the top of the block 113 and outwards out of the holes in the bottom of the block or in the opposite direction. A tube or pipe 122 may optionally be fixed to the block 113 to guide the filament 116 from the output hole to a print or extrusion nozzle.

[0087] Figure 17 shows a building 123 formed out of square section clay tubes being printed. A telescopic printing tube is shown retracted in position 124 and extended in position 125. The nozzles mounted on the end of the tube are rotated so that the square section clay tube is extruded in the correct orientation to sit on top of the previous layer of tube to form the wall of the building. Clay is fed to the nozzles from a pressurised tank 126 using augers 127 that are driven by motors 128 located on the end of each auger tube.

[0088] Figure 18 shows a wide extrusion head with multiple nozzles 129 mounted via a swivelling mount on a moving gantry 130 extruding clay tubes to form wall sections of a building 131.