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Dowsing for studs
Jul. 16th, 2014 11:45 pmI've been trying to find a good location for the can crusher from Lee Valley, and have run up against one complication of my house. Its interior walls are (for the most part) constructed from a material that's closer to sheet concrete than standard drywall, and the nails/screws attaching these sheets to the studs are deeply buried, and well masked. Finding the studs is therefore a bit tricky. The "percussion" method, tapping the wall to find where it sounds less hollow, doesn't work well. Magnetism-based stud finders are also unreliable, since the vibration from sliding the tool across the wall messes up the indication of where the nail is lurking... the attraction between the magnet and the screws is weak.
Last night, I had an idea: a pair of rare-earth disk magnets with a thread caught between them. I used a thread length of about 15 cm, held the free end to the wall, and let the magnets swing gently back and forth as a pendulum. I moved the top end around slowly, to keep the pendulum swinging, and quickly found some hidden screws. Because the weight of the magnets was being supported by the thread, and I was watching for changes in the pendulum's motion instead of trying to see if it was moving at all relative to some fixed point, I had a much more sensitive detector for the buried metal. One's eye is very sensitive to changes in the motion of an object that's supposed to be moving smoothly on a fixed path.
On the down side, there aren't any wall studs behind any of the areas of the kitchen walls that might be convenient for the can crusher to be located.
Last night, I had an idea: a pair of rare-earth disk magnets with a thread caught between them. I used a thread length of about 15 cm, held the free end to the wall, and let the magnets swing gently back and forth as a pendulum. I moved the top end around slowly, to keep the pendulum swinging, and quickly found some hidden screws. Because the weight of the magnets was being supported by the thread, and I was watching for changes in the pendulum's motion instead of trying to see if it was moving at all relative to some fixed point, I had a much more sensitive detector for the buried metal. One's eye is very sensitive to changes in the motion of an object that's supposed to be moving smoothly on a fixed path.
On the down side, there aren't any wall studs behind any of the areas of the kitchen walls that might be convenient for the can crusher to be located.
