Saturday, June 20, 2009

Applied Physics and the Aftermath of a Redwood Fence


i think it has been mentioned that we recently built a new fence. in this case, by 'built,' i mean, 'hired alberto to build,' as we frankly know very little about building a fence. alberto knows a great deal about building fences - note the string, level, and accurately spaced fence posts. our fence is now the envy of the neighborhood - or so we are told.

admittedly, it is a bit nutty to get too worked up over a fence, but this is our first major project that resulted in something being built. i mean, destruction is fun. lots of fun, but from time to time, it is nice to build something. here, we see the sharp contrast of this beautiful redwood fence next to our potential-porch window still stuffed with fiberglass insulation and showing a bit of electrical wire. for certain, we are glad to be rid of that rickety fence; the remaining panels shown in the photo to the right. note the giant posts in the background that will soon support a custom gate.

the careful observer also notes the posts for the old fence behind the new fence. clearly they must be removed. this should not be a problem. the last time we removed fence-type posts from the back yard, they pulled out fairly easily. this fence wasn't built to last a year, so i'm sure the posts will pop out wihtout too much difficult, or so i told myself naively.

here is the thing about building a fence, or so i would be led to believe by the previous owner of this house. what difference does it make if the posts stand straight or the pickets are placed evenly? how important is it REALLY that the posts lie in a straight line and are evenly spaced. it is not critical that the spans are less than or equal to the length of standard stringer lumber (8'). shortcomings in these areas can be overcome by using A LOT OF CONCRETE to set the posts. lots of concrete; that is what is important, should you one day decide to build a fence.

so i started with a shovel, a hose, alberto's giant pry bar, and a positive attitude. after a short while, i had created a public hazard, but could not say i was close to wresting the post fully from the ground. i was prepared to agree with alberto - rent a tractor. but really, i thought to myself, people have been pulling fence posts out of the ground for a long time; there must be a tractor free way to do this. my first thought, of course, involved high explosives, but i wasn't sure i could pull that off without damaging the new fence. no, it would have to be simple levers and torquing devices.

my fence-post removing device is pictured right. it basically consists of a lifting bracket on the post, a cinder-block, and a few 2x4s to adjust the fulcrum height and as a lever arm. as the post starts to lift out of the hole for the first time, it gives a very satisfying "squilash" as it wrests free from the thick clay-dirt and inches toward the sidewalk.

also pictured are two of my deposed enemies. sure, they don't look like much, but when you've just pried them from the tight-clinging mucky earth, they are special. i guess i didn't take any pictures to demonstrate the scale of this accomplishment. the posts are about 3.75" across if that helps. it is my guess that there is well over 100lb of concrete on the end of each post. 8 or 10 blows with an 8lb sledge was typically sufficient to wrest the cement from the posts once they were removed.

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