How to make something that makes (almost) anything.

FINAL OUTCOMES 05_27_21

Key questions
Earthen material is full of materials with varying structural and insulative properties. Why not create an additive assembly system to recombine the soil of a given site into a material with designable performance traits? Can we take air and bacteria and create printed structures that are both lightweight and slowly increasing in strength over time?

Can we create "just in time" mixing of materials with significantly different densities at the end effector of a 3D printing system? Can we do so in a scalable fashion?

Can we create a system that is modular and acessible/affordable?

How are we evaluating success?

Robustness and reproducability. Accessibilty and affordability. Scalability and flexibility.

What we made

1. A stepper control interface and simple driver configuration which we used for all experimental setups from auger mixing to peristaltic pumping.

2. A high volume benchtop paste extruder with the torque to supply thick earthen materials to an end effector through a 1 meter bowdoin tube.





3. Auger system with interchangable, inputs, nozzles and auger screws, which can be easily adapted to different machines.


4. A low cost foam generator ($50) which produces consist fine cell foam for use in cellular/air entrained earth, concrete, or other paste like material.



5. A low cost 3D printed peristaltic pump ($30) that can be scaled to different motors and used to convey a wide range of viscous materials.




6. A dual peristaltic pump mixing assemble for multimaterial extrusion and switching. This system requires further integration with a multiaxis CNC system. Pumping is effective but dependant on position and calibration of supply to pumps. Future work could include a mounting system to allow constant gravity feed of viscous materials. Currently, laminar flow is observed at the mixing output indicating a potential for experimentation with fluidic mixing geomentry at the end effector.






7. A low cost benchtop bioreactor with integrated pump, impeller and control for both. We hope to use this system in our next set of MICP experiments which are nearing full EHS approval (biologists are afraid of uncharacterized mud).


8. (Fun bonus) Mocha diffusion in deflocculated slip.


Who worked on what?

Laura - Bioreactor
Sandy - Foam Generator
Together - Everything else

PLANS FOR FINAL

-Attempt mixed extrusion of preprepared foamed muds using two perastaltic pumps feeding to the KUKA arm. Prepare to demo this system in action.

-Experiment with lowering water content of foamed mixture with alcohol or a deflocculent to minimize slump.

-Run tests of complete clay extruder and complete documentation of design.

-Finish bioreactor and test. Demostrate mixing. Try milling PCB for control.



CHANGE LOG
05_19_21
Laura tested her parastaltic pump system with premixed foamed mud using the improved foam generator. Results are promising, however we still need a robust way to calibrate density.

05_11_21
- New auger system tested (some slightly improved results). Improved foam generator with inline valves and regulators allowing finer control of the output. Tried a new slip based approach with an earthen material closer to a liquid than a solid. Reworked hardware to simplify wiring.

Controlling extrusion with air is difficult without total control of the air system.

05_06_21
- Extruder testing round 4. Successfully printed a small object in clay, bent lead screw. Tested foam mixing and new gradient control system.
04_28_21 - Extruder testing round 3. Auger update. System control update.
After a failure of the PETG printed plunger we opted for a new water jet aluminum design.

04_22_21 - Extruder testing round 2. System control update. Biohacker space access.

04_15_21 - Extruder testing. Clay moves through the system but is slow and the motor stalls.
03_17_21 Now that we have a better understanding of both issues of MICP and foaming agents we have started organizing the overall workflow of the system and subsystems.

03_16_21
Testing AugerV1. The first auger test took a few days to get running. We found our Nema 23 (129 oz.in) motor and 80:1 gearbox was right on the edge of providing enough torque to move material through the hose system. After shortening the hose and tweaking the feeds and speeds we were able to get some clay moving into and through the auger. However after just a few moments of extrusion the tube holding our clay and the 3d printed nozzle assembly cracked under the pressure. As a result we are now reworking the tube and plunger design to use pressure rated PVC pipe and an aluminum nozzle.


AUGER v1


Our first auger design for small scale tests with a slot for testing different filters.


Will a conventional faucet aerator do anything to inject small bubbles in a earthen material as it passes through the auger? We'll find out...






Taking a trick from Tom Lauerman at Penn State we are using frosting tips as easy to clean interchangable nozzles.


TESTING Analog control of auger stepper and air.

03_10_12
NEXT STEPS
-Finish mud/clay pusher. Document design (some open source ones out there, but not very robust)


-Test existing system
-Build system for extrusion level control of air inclusion.i.e. We only want tiny bubbles in the center of the extrusion.
-Consider architectural scale machine designs.
-Build some test control software and mount Auger v1 on a 3 axis system.
03_08_21
THOUGHTS ON SOFTWARE