- Mister Dog
- Dec 27, 2005
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Well, now, let's keep something in mind. If you simply plant the business end of your magnet up against the head of a nail, then it doesn't do poo poo: you're going to have to pull on your magnet with the same amount of force it takes to pull out the nail, and then what was the magnet for?
So instead, I guess we're talking about holding a magnet some distance away from the nail (minimum clearance for the nail to come all the way out, so at least as high as the nail is long), and the nail comes flying out. Equal and opposite reaction etc. etc. means either you're moving the magnet into place on some kind of rig, or you're still having to deal with all the force of the nail-pull being exerted downwards on you holding up the magnet. So I'm thinking like a rolling wheeled tool with a chamber above which hangs a powerful magnet. Might look a bit like a lawnmower.
In any case, since we're trying to invent a useful nail-pulling magnet powered machine, we need to account for the distance between the strongest part of the magnetic field, and the nail itself. So it's not "how strong of a magnet do you need" but "how strong of a magnet do you need at X distance from the metal" so maybe at least 3 or 4"? We may also have to account for nonferrous alloying components because nails probably aren't all 100% iron, right? And you've maybe got the problem of what happens to every loose ferrous object in the room when you bring in or turn on a magnet strong enough to yank a nail out of the floor from a foot up or whatever.
That 240 pounds kastein is estimating is probably the momentary force exerted perpendicular to the surface of the wood in order to get the nail loose, and then I expect it takes a lot less ongoing force to overcome the ongoing friction of prying the nail the rest of the way out, which means we probably only have to care about the maximum force in the equation; that needed to get the nail moving. Perhaps with an electromagnet we can get by with an initially strong pulse followed by a weaker steady pull, which would save us on power a bit?
But now let's consider how much force is also being exerted by the magnet on, say, the galvenized pipe you forgot was under a nearby section of the kitchen floor...
Why you gotta ruin this for us?
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Mar 17, 2016 02:17
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May 16, 2024 09:53
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- Mister Dog
- Dec 27, 2005
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Is the paper even considered vapor barrier? I didn't think it was.
This is a fair point, the Kraft paper is probably more of a vapor retarder than a proper barrier. And anyway, there’s unlikely to be any practical consequences whether it’s applied paper up or down, as the temperature gradient between the floor and the basement will probably never be high enough to lead to significant condensation.
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Jul 25, 2022 01:18
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Mar 17, 2016 02:17
