On Sat, Dec 23, 2006 at 06:13:32PM -0600, John Hasler wrote: > > The drilling technology is also 19th century. Although a rotary drill is > faster (though still 19th century technology) a cable drill is something > that anyone able to keep any sort of machinery running could maintain: it's > just a heavy weight on a cable, lifted up and dropped over and over. > I see. Minimal moving parts, right? > I suspect that a more serious barrier is the cost of the steel casing. > True. However, PVC casings are also used. They are probably not as good, but a foot of 6" PVC is way cheaper than a foot of 6" steel casing. Regards, -Roberto -- Roberto C. Sanchez http://people.connexer.com/~roberto http://www.connexer.com
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