Dan This shows up one of my favorite nit picks, the difference between resolution and accuracy
Obviously the resolution of your level isn't what you think. The error is not noticable on the tiny slant of one or the other beam, probably both. but the same level change shows up on the 2 by 4 which is shorter. I think, maybe, or not? tom fowle On Tue, Oct 20, 2009 at 10:09:16AM -0400, Dan Rossi wrote: > I need to call in NASA to investigate my basement. Apparently, my > basement is a very special place where Euclidian geometry goes right out > the window. > > I have two parallel beams that are nice and level. The level beeps > continuously as I move it along the beams. I lay a 2X4 across the two > beams and that 2X4 shows level. So, if the two beams are level, and they > are level to each other, then a 2X4 placed across them at any point will > be level. > > Here is where it gets interesting. At one end, the 2X4 is level and all > is happy. At the far end, if I level the 2X4 it is well above the one > beam. And I don't mean like a quarter of an inch, I mean like an inch and > a quarter or a bit more. > > This is actually impossible. But that is why my basement must be > declared a non-euclidian zone. > > I think it has to do with the fact that even if the level is off a tiny > bit, like 0.1 of a degree, over 15 feet, that is actually 5/16 of an inch. > Do that three times and you get nearly an inch. Plus the middle beam that > I was trying to level wasn't fully supported yet, so is bending and > flexing, and so was the 2X4 I was using. Add all that up and you get a > lot of error creep. > > I need an 8 foot level, but not sure I can get that one passed SWMBO. I > might try using my saw guide on edge which should be pretty stiff. > > -- > Blue skies. > Dan Rossi > Carnegie Mellon University. > E-Mail: d...@andrew.cmu.edu > Tel: (412) 268-9081
