Coffee Bean Bridging
My coffee grinder sometimes pauses in its labors, and makes a high-pitched whining noise that is nigh unbearable to the uncaffeinated ear. The noise happens because even though there are plenty of beans in the hopper, they’ve managed to arrange themselves in such a way that they don’t fall down. A good jostle of the grinder will set things right.
This problem is not new. Random loose particles frequently produce such quasi-stable, gravity-defying arrangements. Back in the day when I was working on well drilling projects, we worried about it happening in the gravel that surrounds the well casing. This gravel is installed to prevent sand from the surrounding material from getting into the well and wrecking the pump. If the gravel “bridges” during installation, leaving a gravel-free gap underneath, that’s a place where sand will get in.
There are a number of ways to avoid gravel bridging. In fact, this is the subject of quite a few U.S. patents (I stopped counting after the first half-dozen or so). I was hoping that well drilling would give me some engineering inspiration that would make my mornings more pleasant, but no.
The cheapest way – the one included on technical specs for municipal water well contracts across Southern California – is to simply drop your gravel from as small a height above the top of the growing gravel pack as possible, and hope for the best. In the morning before coffee this can end up with a fully inverted bag of beans and a mess, if I’m not careful, but engineering is all about balancing competing priorities for your project.
More advanced ways include pouring the gravel in a high-viscosity slurry (perhaps I could embed the coffee beans in corn syrup? Mmmmm yum!) or using a complicated arrangement of screens, perforations, and funnels to drop the gravel. Much as I would love to infringe on ExxonMobil’s intellectual property every morning, I’m pretty sure these techniques are also nonstarters for coffee grinder adaptation.
Of course, the real reason people have invested so much energy into developing methods of pouring gravel is that you can’t just reach out and give the well a good thwack, like you can with a coffee grinder. If you could, I’m sure that is exactly what drillers would do.
Maybe the real lesson is that I need some OSHA-approved hearing protection to wear while I make breakfast.
Happy Monday, everyone.