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Here's an example!

I recently used their sister library (build123d, same devs) to build a rotary slide rule bracelet for multiplying three-digit numbers. It was a great experience and wouldn't generally be easy to do with Fusion 360. My bracelet gets quite a lot of comments when I wear it in public. :-)

Here's an IPython notebook with lots of pictures so you can see how the different operations come together: https://github.com/gcr/sliderule-bracelet/blob/main/version-...

build123d is quite different stylistically from cadquery, but this should give you the flavor of programming-oriented CAD at least.



Nice model, but also a great notebook. Really like this "literal coding" style for CAD in a notebook. I still sometimes prefer GUI cad for simple stuff, CadQuery is not always that easy to write. But when iterating over something complicated, the notebook style development is really nice. And being to compose a model using functions and iterators instead of the clumsy GUI workflows is a godsend. Also time I tried Opus was more helpful and capable than I would have thought. Not good enough to one-shot yet, but it is very helpful nonetheless


Thanks for this! It's really fun. My older kid now has a vanilla sliderule bracelet. The younger is getting a smaller bracelet of the same design, but with dragons on it :-)


Ah so cute!! I’d love to see pictures of your changes if you care to show them :-)


https://imgur.com/a/fssIujT

Happy to share source if you like, but it was nothing complicated: - ask aistudio.google.com to draw a bunch of dragons - trace one to svg - make the bracelet a little smaller


> wouldn't generally be easy to do with Fusion 360

Actually...

https://www.youtube.com/watch?v=DNiQJyRTs50

You would create the numbers and marks in a vector drawing program (Inkscape, Affinity Studio, Illustrator) and import that into Fusion.


Sure but like, that is specifically NOT easier if you need to iterate once initial implementation is complete. At least in my opinion as an industrial designer turned software engineer, which I only mention to assert I’m experienced in both sets of tools.


True, the logarithmic scale lends itself to programmatic creation. I just wanted to show that the wrapping part is easy. Actually much easier – that code looks non-trivial.


This is so cool! I'm going to have to try building this. Thanks for sharing!


how does it work? (the multiplication)


Becaus ln(A*B) = ln(A)+ln(B), you need 2 sliding elements and you work in logarithmic scale. Look at "slide rule"[0], this is really nice stuff.

[0]: https://en.wikipedia.org/wiki/Slide_rule


Are you asking how the bracelet multiplies two numbers? It's the same idea used by slide rules -- you take the logarithm of the two numbers, then add the logarithms instead of multiplying -- same result, with somewhat less accuracy depending on available decimal places.

This method was widely used in the pre-computer era to save time in calculations. Tables of logarithms (and slide rules) were a mathematician's best friend.


lol, as an engineer I'd never considered that other disciplines used slide rules voraciously




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