Removing stuck nails with a propane torch скачать в хорошем качестве

Removing stuck nails with a propane torch

A common trick used by machinists is to use heat to alter sizes slightly for really tight-tolerance fits, like when pressing in a bearing. A cold bearing will press in with slightly less resistance. Another trick is the case of loosening a nut that's stuck on a bolt by using a torch; the heat will eventually 'break the crust,' and get the nut to start turning. The punchline here is this: heat causes metal to expand. The corollary to this fact is that the removal of heat causes a corresponding contraction. But the measurable amount of this change is still not as dramatic as you might think. Two things to consider about heat: 1) it is nothing more than atomic/molecular motion, and 2) heat likes to dissipate in, along, or through the easiest possible path. This process of heat moving away from its source is called diffusion, and it works in precisely the same way that an apple pie scented candle will slowly fill a room with its scent. Back to the first point- warm atoms move faster than cold ones do, so think of a warm object as a room with a fan, where the candle's aroma will spread much faster. Aside from some obvious crystallizations, there is no real difference between a solid, liquid, or a gas from the atomic perspective. Those are labels that we apply up here, where atomic density seems to manifest as a 'hard' property in our physical world. Down there, it's all just a boiling stew, where there are some occasional lumpy arrangements. I'm drifting off. Look up 'amorphous solid' if you want to tumble down that rabbit-hole. The easiest way to see or measure the expansion and contraction cycle on a material is to find an example of that material in a long size. For example, with a nail that's only 3” long, even if its metal were to expand 5% with heat (which is not realistic), it would still only grow a little over 1/8”. But with an I-beam that's 30' long, that same percentage of growth would be around 1.5 feet. Thankfully (in reality), thermal expansions are very, very small numbers in most cases. Nevertheless, it can have a serious collective affect on long lines of a substance, and so it's a pretty big consideration for engineers. A great example is with train-tracks: they can turn to spaghetti if they are not allowed to flex correctly. Ok, back on track: in the case of the nail being heated, it grows just a little bit. Once the head is bright red, the nail is 'full' of heat at the top, and so the heat will naturally try next to diffuse down through the rest of the nail. As it does, it causes just enough of an expansion to break loose the 'stuckness' of its rusty surface from the wooden substrate as it goes. The wood has less of an ability to allow heat to diffuse than metal, so it's more of an insulator. This 'thermal conductivity' gets our nail to grow without losing all of that heat to the wood; the heat moves quickly through one substance, but not so with another. Interesting discussion topic for another place: the strange relationship of density to types of conduction. From bridge rivets to proteins—with any structure—our physical world is geometry at work. Once, while working for a roofing/siding outfit, we had this recurring problem with a stubborn condo-association. Come to the sidewalk of this memory with me, but do not step on the grass. That chemical smell is the opportunity cost of enjoying a green carpet free of those pernicious yellow spots. Personally, I like dandelions. They have such a pleasant smell, and the pollinators love them. Ahh, my antithesis! Weeds? Ha. Morons! That's verdant variety! The elusive pursuit—the illusion of perfection—is for idiots, especially when it's at cost to the peace. Or to sanity, I'll argue. Their lifestyle was laughable to me; they conscript themselves to frivolous constraints in some vain attempt to procure order for their little world. And under the added strains of their ever-increasing preoccupation with pettiness, amidst yappy little purse-dogs, lollipop figured shrubbery, and garbage cans placed only in their spacial and temporal designations, their fantasy would not support seams in aluminum fascia. And so it was, that despite my boss's emphatic explanations of thermal expansion to the management of their white-haired commune, they would continue to have us install the 20' rake fascias. And with each yearly cycle, as the trim nails remained fixed in place, the aluminum expanded back and forth +/- nearly one-half an inch, until each nail had worked a groove. And so the fascias would tend to fall around the winter holidays, onto snow-blanketed yards normally free of footprints. And that's precisely when they could be re-installed by my slovenous bunch of compatriots: work-trucks, ladders, saws, drills, horses, cords. Muddy boots and all. Chew-spit in the snow. Cyclical. Seasonal. And perfect. It's a type of restoration, with an age-old tendency. Maybe we can't have order, but at least there's always gonna be balance. Music of the spheres.