While something as simple and indestructible as an anvil might last "forever" it may become obsolete.
A reader writes, in response to my posting on fixing things, whether something like a wrench, with no moving parts, could truly be made to "last forever". Forever is a long time - infinity. So no, in real terms. Atoms eventually fall apart, over time, even without the intervention of reactive elements such as oxygen.
But a lifetime? Sure. But even then, it might become obsolete.
I had a set of original wrenches and tools for my 1941 Ford 9N tractor. Each was stamped with the "Ford" logo, and while they worked, they were sort of odd by today's standards - small and angled weirdly. But after 70 years, they still worked. After 70 years the tractor still ran, although eventually I had to replace a timing gear in it. So yea, things can last "a long time" but that is hardly "forever".
Like so many other things, though, it was woefully obsolete. Ford tractors (now called New Holland tractors) make excellent lawn mowers and not much else. The farming world moved on since 1939, and tiny little tractors that "could be driven by a 9-year-old" (and were - a friend of mine grew up on a farm and his Dad forced him to plow with one!) became useless. You see them all over the place (along with the predecessor Fordson) as lawn ornaments and nothing more. Today, mega-tractors dominate the scene, and in recent years, the rubber-tracked tractor (which helps avoid soil compression) has made even the monster tractors obsolete.
But tools? Yea, those too. Back in the day, the Brits used "Imperial" standard tools, and something called "Whitworth" wrenches. A set of Whitworth tools may be of interest to the owner of an antique British car, or as a novelty item, but no longer useful as tools for general use. In more recent times, the switch from "English" to "Metric" nuts and bolts in America (and we're "not on the metric system," right?) has rendered many a toolbox obsolete. As a lad, I spend a lot of money accumulating a toolbox full of "English" sockets and wrenches, but by the 1980's, I had to repeat the experience to get an entire set of Metric tools, as American automakers made the switch.
And as for anvils? Well, you see them a lot in antique shops, to be sure. The Village Smithy no longer beats out horseshoes by hand, under the spreading chestnut tree.
Now, you may think you are immune from this obsolescence - but think again. A lot of what you think of as settled tool design is relatively modern, and already obsolete. I have a drawer full of screwdrivers in my tool chest, and the flat-bladed ones are useful for prying things open or as makeshift chisels. No one uses flat-head screws anymore. Maybe you find them on old furniture or on old door hinges on old houses.
The Phillips head rules! So that is settled, right? Well, as the above video from "The History Guy" illustrates, the Phillips-head screwdriver is a relatively modern invention. As a kid growing up, I was always mystified by my Father's fascination with them, and now I realize it was something invented in his lifetime. Hell, the airplane and automobile were things invented only a decade or so before he was born. From flying flivver to moon landing - in one lifetime. Our civilization is not as old as people think.
But even the trusty Phillips-head is under attack. Our camper, made in Canada, uses square "Robertson" head screws (which other RV manufacturers in the States use) and of course, torx bits are taking over the world, along with a host of other, unique bit shapes and sizes.
And this stuff keeps changing when you aren't looking. I thought I was up-to-date with my Makita screwgun (Phillips head, natch!) and my galvanized decking screws. Not only are they obsolete, they are NLA - the new non-arsenic pressure-treated wood will rust through galvanized screws. Welcome to the new world of yellow screws and green screws - all with torx bits - for yellow wood and green wood. And of course, some have moved on from even that, to stainless steel.
So yes, maybe a wrench could last a lifetime or two (but not "forever") but nevertheless become obsolete in short order.
And that is why, in short, it makes no engineering sense to design for "forever". I owned a Mercedes W123 sedan (a 1985 300D, non-turbo, grey-market) that had 140,000 miles on it when I bought it. I sold it with close to 200,000 miles and they regularly go 300,000 miles or more before needing major repair. It was the last of the Teutonic Tanks. Today, Mercedes are made of plastic and look like crap after a decade or so.
But that old Merc - sweet ride, no? No air bags, of course. And the radio was AM/FM with two speakers. It had none of the toys or conveniences we expect today - but of course, three ashtrays. It was a nice car, but obsolete. You still see one or two tooling around these days, but of course, even a "forever" car doesn't last forever, and most are now driven carefully as antiques. Many more went to the junkyard when they got into wrecks - another reason not to build "forever."
And more plebian cars? Once they reach a certain age, it isn't even worth putting new tires on them. The old joke about "doubling the car's value" by filling up the gas tank literally becomes true. Literally, in a literal sense. And speaking of gas, that has changed over time, to the point where running an old car on today's gas becomes problematic. Cars designed to run on leaded gasoline often have valve guide wear, as the tetra-ethyl lead helped keep those lubricated.
Engineering isn't the art of making things last forever, but making things last for a certain design life at a practical cost to the end user. This means trading off considerations of weight, appearance, materials, design life, cost, and functionality. If you can come up with something that works well for an affordable price, and lasts a decade or so, you've done an outstanding job. Making something that no one can afford and will last so long to the point where it is obsolete? Poor Engineering.
But even if you do all the right things, there is always some flaw you might not anticipate. And this happens with any product - and the more complicated the product, the more likely this is to happen. And sometimes you can't predict what people will do "in the field". A mechanic comes up with the clever idea of reducing the amount of time needed to swap engines on a DC-10 by hammering out the shear pins. What a time-saver! What a great way to induce stress cracks! What a great way to kill people!
That is why, while I am disappointed my vacuum cleaner broke, I realize that such things can happen. I used to do "Failure Mode Effects Analysis" at Carrier, and we used MIL-SPEC-217D to determine how long an electrical circuit would last until failure. Each component has a failure rate per 1,000 hours of use (or whatever) and you multiply these together to figure out the overall failure rate. Switches, light bulbs, and power supplies had the highest failure rate. Switches in particular, with their moving parts and arcing electricity (which produces insulating oxides on the contact surfaces) tend to be big problems. So as an Electrical Engineer, it doesn't surprise me that the switch went bad.
Fortunately, a replacement switch is available - from the UK of all places! for about 15 bucks. The seller has sold 760 of them, so that tells you something right there. If you carefully pry off the switch cover (from the part nearest the handle, lest you break the hinge) the switch removes with two screws. Solder a new on in (or use the provided crimp fittings) and you're back in business. Or just screw a doorbell button on there, if you are not particular.
Or, you might get a free replacement power head from Bissell, as the problem is apparently well known. A $141 value! Sometimes companies do that for customer goodwill, or to avoid a class-action lawsuit. In the business, we call these "hidden" or "secret" warranties. GM replaced a lot of THM-250 transmissions in the 1980s, BMW a number of 5-series V-8 engine blocks in the 1990's, Chrysler repainted a lot of Dodges with peeling paint in the 2000s.
But expecting things to last forever isn't realistic. Or useful.