rod through tree
Monday, November 30 2009
setting: rural Hurley Township, Ulster County, New York
Evidently there had been strong winds blowing through Hurley during our time down in Maryland. Our welcome mat (which doesn't actually say "welcome" or anything else) had been nearly overturned, a towel had been unseated from its perch on the brownhouse rainwater collection piping, and a piece of scrap aluminum had blown down from the laboratory deck. But most vexing of all was that the 5/8 inch cable which I'd installed to stabilize the large damaged pine just north of the house had pulled loose and fallen to the ground. This cable had been attached at either end to large "screw eyes" that were actually pivot sockets for the installation of a farm gate. These pivot sockets were far bigger than any actual screw eyes I could find, and featured eyes of solid metal all the way around (lacking gaps), shafts of half-inch steel, and three inches of threading. I'd noticed a big difference between the force needed to torque one of these "eyes" high up in the damaged pine (not much) and that needed to torque another low in the base of the oak serving as the anchor (a lot), but I'd never imagined that the force of the pine in the wind would be enough to just pull the "eye" out of the tree like a nail, which is what had happened. The half-inch shaft of the "screw eye" had even been somewhat bent by the ordeal.
The pivot socket I'd used as a screw eye to keep the damaged White Pine north of the house from falling southward. The force of the wind not only pulled this out of the tree like a nail, it also bent the half inch steel into a gentle curve.
So today I went to Herzog's in Uptown Kingston and bought a replacement for that unworkable screw eye. I found a solid cast bolt eye made of 5/8 inch steel (price: $10) and two feet of 5/8 inch threaded rod (price: $5). There was no solid way to connect the two, so I ended up connecting them with a single compatible nut and then arc-welding the fuck out of all the resulting joints. The result was a big solid eye on the end of two feet of screw thread.
Up in the tree, the task of drilling all the way through the White Pine proved a much bigger job than had been the original three inch pilot hole (whose angry remains I reused). It turned out that the tree was about 14 inches thick at this point, some twenty feet above the ground.
This time I attached the cable to the eye with as much as of the threaded rod protruding from the tree as possible so I could then draw the rod from the other side by tightening the nut, thereby tightening the cable. I'm guessing a loose cable contributed to the failure of the previous support system, since it permitted the massive tree to develop some momentum before the cable's tension brought it to an immediate halt. The old "screw eye" had probably pulled out over the course of many tree swayings, each of which had acted like a massive inverse hammer blow. Now, though, with the cable attached to a rod running entirely through the tree, the only possible failure at that end is with the weld.
I didn't bother to replace the gate hinge socket forming the screw eye at the other end of the cable. That, as I said, is in oak, which is a much tougher wood than pine.
Later, I got to thinking about the massive force of swaying trees, a force so powerful it could pull three inches of a coarse-threaded half inch screw out of pine. I wondered if this might be an inexpensive way to tap natural wind power. Some sort of fluid pumping system could be set up, powered by a swaying tree pushing a piston inside a solidly-mounted cylinder, and that fluid could be used to do work or generate electricity.
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