Whenever a pile of finely sifted dirt is dumped into the hopper on a large CEB machine, that soil slips down the sloped sides and comes under pressure from the pile above. The lower dirt forms a bridge under pressure—regardless of how well sifted the soil might be.
In the past, we devised a safe and effective shaker to rock the hopper and theoretically keep soil flowing evenly into the block press. However, the bridge constantly reformed. Shaking more than we already do would be damaging to the electronics and eventually to the welds. We have decided to abandon the shaker and use its motor to power an internal auger.
We now have designed an auger with carbide teeth inside the hopper that will be turned by the Shaker motor. We will place this auger just above the block chamber so when it turns the dirt uniformly falls into and fill the chamber for pressing.
Since the bridge consistently forms about 12 inches from the hopper saddle, placing the auger at this depth should stop bridging and enable a very well mixed dirt flow into the block press chamber.
This first week of November will see us complete testing of various amendments to our soil to see which produces the least expensive and strongest block. While the piles of block are curing this week, we will modify the hopper for full-scale production once we get back the testing analysis.