It was raining for a week straight, and this Thursday, we finally documented initial field operations with our open source CEB press – The Liberator Beta v2.0. We used the soil pulverizer to pulverize the soil, and we used the tooth-bar bucket to load the machine:
The run shown displays a pressing rate of 11 bricks per minute, using LifeTrac on medium-high throttle as the power source. These encouraging results also pointed to the need of certain adjustments for control optimization. These changes should allow us to achieve about 2-5 pressing rate improvement over the above result, and they should also allow for easier adjustment of brick size and of brick compression.
The automatic controls have been described in previous posts. In essence, the micro-controller uses Hall effect probes and magnets for position detection to sequence the hydraulic solenoids in the order required for brick pressing. We are using two position magnets for each hydraulic cylinder. These magnets are also used to change the brick thickness and brick compression strength – by moving the magnets. These are Nd-B supermagnets, so it is sufficient to slide the magnet to a new position to make adjustements. Since the position magnets are set at the beginning and midpoint of each stroke, the endpoint of the stroke is determined by timing.
Our next step is to install 3 magnets instead of two, since it turns out that this is an easier route for making adjustments. Moreover, it turns out that we can run the two cylinders not in sequence, but in parallel – to gain in brick pressing rate. The last point is feasible because we are reducing the flow in the secondary cylinder so it does not move too fast. We can tap the remaining flow more efficiently by allowing the 2 cylinders to operate in parallel.
These are all details, and the control code needs rewriting. All together, we look forward to impressive improvement in our second day of system shakedown under field conditions. We had Sean and his crew do some documentation on the brick pressing day, so more higher quality video footage should be forthcoming. Sean will also be joining us this summer on time as a full-time documentor for the skunkworks.