Video: Pradeep Devadass and Zachary Mollica
With the last phase of scaffolding removed we can finally experience the space.
With the last of the on site connections made, the truss’ scaffolding has been removed. Now self supporting, the truss spans 25 m x 10 m and rises to 8.5 m at its zenith.
Big day – had a mobile crane on site to lift the two halves of the truss in to place on top of the temporary scaffolding supports. Everything fits! Now we need to complete the bolted connection between the truss segments and the tops of the tripod legs.
The first truss-half has been complete and carefully moved out of the Big Shed, making the assembly jig available for the next half. Video: Zac Mollica.
10 forks are currently placed onto the assembly jig along with 6 straight timbers. With all of the pieces temporarily held into their final positions using straps we are beginning the process of bolting together. In assembling, small errors that have accumulated throughout the process from scanning to milling become evident. As well as developing […]
With the pre-assembly of the first half of the truss well underway, the robotic arm is in full production mode on the forks and top chords for the second half.
Each fork leaves the robot cell as a finished component with all of the connection geometries required to connect it to its neighbours. Due to their large size we required a method to locate all of the pieces with respect to each other before bolting together. A large assembly jig has been constructed which will […]
The yard has been full of activity these last few weeks. The eight roof panels are well underway and the finished wall components which will eventually be assembled on site are piling up.
The four tripod units are an important part of the truss. As they are being manually fabricated but must align to the precision of the robotically fabricated pieces of the truss, a complex series of jigs and techniques has been developed.
The connection between the end’s of the fork branches and the top chord members has proved the most complex to detail. In the first prototype we had a rectangular mortice and tenon but this proved tricky visually (a lot of the mortice’s surround flat was exposed) and in engineering terms, as it is difficult to […]
We have started machining the first forks with the robot arm. The first step (photo 1) is to register the positions of the support trolley by pointing the robot a the top of each of the three support bolts that correspond to the fork reference positions from the scan. We then (photo 2) bring in […]
As well as undergoing robotic machining processes, each fork underwent a series of manual operations including: cleaning and boron treatment, and connection finishing. While the forks were digitally scanned, top chord components were manually surveyed to determine their centrelines.
The connection strategy for the truss relies on the principle that we can precisely machine each connection face so that their relative positions are correct. This means that although our scanned mesh geometries are not perfectly precise (we find errors up to about +/- 20mm) we can use the accuracy and repeat-ability of the robot […]
It’s been a busy week, this one! After studying the defects, we selected 20 forks and generated what we hope now is the final truss geometry with the 3D meshes. This generation was carried out by Zac using the Galapagos evolutionary solver in Rhino-3d to optimise the truss arrangement. The summer-builders have been busy debarking, […]
Bath University has been carrying out load tests on forks as a part of an on-going research by one of their students. They have used Beech forks, to help understand the grain structure and stresses the fork would be under in our structure.
Aurimas, a visiting student from MIT doing his research on roundwood timber columns has been helping us understand, design and fabricate the “tripods” which form the four legs of the truss structure. We built a 2/3rd scale tripod mock up to understand the process and assembly sequence for the final production.
Done processing 3D meshes for all twenty-five of the forks! Each fork was marked with reference points photographed from approximately 20 positions for uploading to an online photogrammetry service that returns a 3d mesh of the photographed surfaces.
Phase 1 Summer Builders arrived this weekend and dived straight into project-mode. They built trestles for the prepping the forks to be photographed. A week spent in pre-processing of the forks – being debarked, prepped, measured and photographed to get the 3D mesh. Students along with the summer builders tested the robot arm checking for […]
Preparing for the AA’s Projects Review Exhibition 2015. The exhibition displays the Biomass Boiler House book hints of our project including a 1:20 model and the 2/3 mock-up.
We are testing our first run of the whole production sequence to build a 2/3rd scale mockup of a section of the truss this week. Connection details are being worked on – using the 3D scan mesh data. Also, fabrication of a lifting gantry and robot cell trolley began – as part of the robot […]
Once the forks are brought to the yard, they are debarked and prepped for being photographed for 3d-scanning photogrammetry. A drilling template was devised to help locate 3 reference points to be picked up in the 3D meshes, to enable us to correctly located the fork in the robot fabrication cell.
Initiated the pre-fabrication process with foresters Chris and Nick, felling the selected trees after locating them on the map with the acquired GPS data. With some of the forks breaking after being felled we’ve been introduced to the possible defects and the difficulties we might have to prepare for.
We’ve been testing techniques for arranging fork geometries onto the target truss chord curves, using scripts that optimise the placement to minimise the angle change between segments.