this post was submitted on 12 Oct 2026
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Showerthoughts
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A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. The most popular seem to be lighthearted clever little truths, hidden in daily life.
Here are some examples to inspire your own showerthoughts:
- Both “200” and “160” are 2 minutes in microwave math
- When you’re a kid, you don’t realize you’re also watching your mom and dad grow up.
- More dreams have been destroyed by alarm clocks than anything else
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- If your topic is in a grey area, please phrase it to emphasize the fascinating aspects, not the dramatic aspects. You can do this by avoiding overly politicized terms such as "capitalism" and "communism". If you must make comparisons, you can say something is different without saying something is better/worse.
- A good place for politics is c/politicaldiscussion
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An engine lathe is one of the only standalone machine tools that is capable of recreating itself in its entirety.
And not only can it recreate itself, with the correct tooling setup it can recreate itself in a more precise, accurate manner than it itself is built.
Wait how
Basically, any moving mechanical system has slop/clearance in it. When operating machine tools this is called "backlash", aka how far you have to turn an adjustment handle before it creates a real change in machine position. Any and all moving mechanical systems will have some non-zero amount of slop.
Skilled operators can compensate and "take out" this backlash so that each cut runs perfectly true. Basically as long as you take a "sloppy" machine and always adjust it to run against the very edge of its "sloppiness" zone, you get high precision... I have used lathes at my old college with probably 0.100" or more of backlash and was still able to turn parts that had less than 0.001" of runout.
And obviously once you get to computer controlled machining centers the backlash compensation can be baked into the program to get perfectly true cuts each time.
Not OP, and I'm not sure how the lathe itself does it. But it shouldn't be surprising that it's possible to create more precise tools from less precise tools. Otherwise it would be impossible for us to ever create tools more precise than our own hands and fingers.
can it do that indefinitely?
In terms of precision? Not entirely, there are limits to true mechanical precision that is necessitated by lubrication for moving parts, running fits, and natural vibrations.
When combined with other systems (aka computers) you are able to build shit like ASML microchip lithography machines...