26 June 2014 : Today I bought a drill-powered pump-attachment to try to move the EA along. I have decided to have a fixed-length of tube that is lifted by the BilBot as the tower is built.
Substrate will need to be pumped along the entire length of the tube, and up the vertical height of the tower.
I am sure that the substrate will need some tweaking – currently it is very viscous which is very likely to be problematic. Nevertheless, this device offers a very good starting-point for me to finally push the EA project towards having a working prototype.
July 06 2014 : The pump works fantastically. It is very powerful – with water.
I put the pipe to a height of around 2 metres and once I’d ironed out the glitches with connections fired the drill up it pumped water to 1.5 metres or more above the top of the hose end.
The diameter of the metal tube seems about half that of the yellow hose, which might be why the pressure is so high – possibly it is double that of the suction force.
Moving materials upwards from storage tanks underneath the base will not be a problem from a pressure perspective.
On the inside the pump is pretty perfect for my intentions. It is nothing more than a well-machined water-tight container with rotating rubber fins inside it. The rubber fins rotate around a point located offsetted towards the bottom so that the fins bend and increase pressure.
I have only tested the working of the pump using water. A series of experiments needs to happen now – to understand how well the pump will handle various dilutions of starch, mud, and clay. Something to watch out for will be any eroding of the rubber fins inside the motor when the fine grains of clay and mud are pumped at high speed.
Other aspects that need some working on include:
- adding materials to the high-speed water after its exit from the pump.
- catching and storing the pumped materials at the top of the structure.
- recording any change as the height of the extrusion head changes – pressure etc
- developing the correct building materials – it’s possible that capsules of substrate with a soluble skin can be moved upwards, or small fine grains of wax or plastic can be moved upwards and melted later.