111–120 of 132 posts
Super Easy Improvement: add thousands separator. It's easy to mistake 1,500,000 BC with 150,000 BC. Also zoom in/out would be super useful! Great idea though!
Earlier quoted context omitted.
Interesting. On that note, Da Vinci's design (which I was fortunate enough to see a replica of at a local museum) was also very clever, being suited not only for screw cutting but also screw origination, as it could make new screws more accurately than the two leadscrews in the machine itself, and swap them out to improve its own accuracy. But I suppose it doesn't extend that date even further back because it wasn't…
having no experience in precision manufacturing and metrology... how does one become more precise than input tools?
For example, Da Vinci's machine cuts the new screw blank in the centre of the carriage, which is driven by leadscrews on either side. The nuts would have likely been something like a wide strip of leather clamped over the screw thread, so there's enough compliance to average over a few pitches of thread, and the position of the cutter would be close to the average of the position set by each leadscrew thread.
Imagine the rough-cut screw threads have a pitch vs rotation angle described by p1(θ) and p2(θ). Running the machine then creates a new screw which is nearly a duplicate of the drive-screws in the machine but with pitch p3(θ) = (p1(θ) + p2(θ))/2. You can make two of these screws and swap them for the two leadscrews in the machine (it's built to be easy to do this). The random errors from a rough-cut screw gradually average out. But the cleverness doesn't end there. You then flip one of the screws backward end-to-end, so now you're averaging p3(θ) with p4(L-θ). You can also offset θ by any amount for either screw by offsetting the change-gear and re-clamping the carriage nut. Repeating these actions, you gradually can eliminate all systematic thread errors from the initial rough-cut screws and converge towards cutting a screw with nearly-constant pitch.
(It doesn't end there either; there's really a lot of flexibility with Da Vinci's design. Changing the gear ratio lets you create a fine-pitch thread from a coarse-pitch thread, or vise-versa, or cut a multi-start screw by rotating the blank 180 degrees or end-over-end).
Earlier quoted context omitted.
what's the technological difference between Chinese Writing and Western Writing? why are they separate?
(Not an expert but) Chinese writing is hieroglyphic, wheres 'western writing' is phonetic. Western writing has a very small character set and is thus well-suited to a printing press, whereas hieroglyphics have thousands of characters (for thousands of concepts) but aren't fundamentally linked to the language like western characters are.
I'd expect something things like Chinese Writing to be a big upstream dependency, but here it's a terminus. Detecting a western-bias in the sourcing.
Earlier quoted context omitted.
having no experience in precision manufacturing and metrology... how does one become more precise than input tools?
The main way is by averaging error terms toward zero. For example, Da Vinci's machine cuts the new screw blank in the centre of the carriage, which is driven by leadscrews on either side. The nuts would have likely been something like a wide strip of leather clamped over the screw thread, so there's enough compliance to average over a few pitches of thread, and the position of the cutter would be close to the average…
Earlier quoted context omitted.
The main way is by averaging error terms toward zero. For example, Da Vinci's machine cuts the new screw blank in the centre of the carriage, which is driven by leadscrews on either side. The nuts would have likely been something like a wide strip of leather clamped over the screw thread, so there's enough compliance to average over a few pitches of thread, and the position of the cutter would be close to the average…
The traditional way of making a multi-start screw is to use a dividing head and rotate the part an appropriate angle. If you're working with change gears, choosing a gear that's a multiple of the number of starts could provide alternate way to do this.
My particular interest is in screw cutting lathes, and it appears that the Wikipedia entry[1] (on which this seems to be based) was off by about 25 years (1775 instead of 1800), and thus copied to this work. I've let the folks at Wikipedia know. [1] https://en.wikipedia.org/wiki/Screw-cutting_lathe
This 2D map is hard to explore since it's so sparse. I have to follow lines to find each thing, since it's 99% empty void. Is there a snap to next item hotkey? Am I just doing it wrong?
I'd expect something things like Chinese Writing to be a big upstream dependency, but here it's a terminus. Detecting a western-bias in the sourcing.
This is truly amazing. I love it! Found a minor nit — the entry for “shoe” is at 3500 BCE and links to the Wikipedia article for “sandal”. But the Wikipedia article for “shoe” [1] indicates that the earliest shoes (apparently not sandals) were worn around 7000-8000 BCE. [1] https://en.m.wikipedia.org/wiki/Shoe