
Make Your Own Pythagorean Cup - JohnHammersley
https://divisbyzero.com/2018/12/31/make-your-own-pythagorean-cup/
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walrus01
You can also 3d print one:
[https://www.youtube.com/watch?v=sJV1R802ZBk](https://www.youtube.com/watch?v=sJV1R802ZBk)

[https://www.thingiverse.com/thing:123252](https://www.thingiverse.com/thing:123252)

[https://www.yeggi.com/q/pythagorean+cup/](https://www.yeggi.com/q/pythagorean+cup/)

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jstanley
I just modelled a 3d-printable version of the "tube hidden inside handle"
design:
[http://incoherency.co.uk/interest/pythagoreancup.stl](http://incoherency.co.uk/interest/pythagoreancup.stl)

It's not printed yet, but apart from the excessive overhang at the top of the
handle I think it will work.

Side view at 50% opacity: [https://img.jes.xxx/2003](https://img.jes.xxx/2003)

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mrfusion
I’d make sure the tube is pretty wide. I made one and it wasn’t very
impressive to wait 30 seconds while the water trickled out. Just seems like a
leaky cup.

I’d go more for a toilet flush type of thing if I redid it.

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jstanley
You're right :)

It finished printing and works as it should, but it takes an extremely long
time to drain.

tobr suggested an alternative design elsewhere in this thread:
[https://i.postimg.cc/FR7Qc9M5/0845194-D-F5-DE-46-D6-8200-CB9...](https://i.postimg.cc/FR7Qc9M5/0845194-D-F5-DE-46-D6-8200-CB9-F8-ABDA332.jpg)
\- I think it would be easier to conceal a larger tube within that, so I might
have to try that too.

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mrfusion
Could you share the file with me if you end up doing that other design? I’d
love to try it out too.

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jstanley
Here you go:
[https://incoherency.co.uk/interest/pythagoreancup2.stl](https://incoherency.co.uk/interest/pythagoreancup2.stl)

And a 50% opacity view: [https://img.jes.xxx/2005](https://img.jes.xxx/2005)

The first cup took 90 seconds to drain about 200ml. The cross-sectional area
of the tube in the second version is about 4.7x larger, so if my beginner-
level understanding of Bernoulli's principle is accurate, I expect it to drain
about 4.7x faster, so maybe it'll empty itself in 20 seconds instead of 90.

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jstanley
This one drains in 12 seconds, but only contains 150ml due to the reduction of
the inner diameter at the bottom.

The average flow rate is 12.5 ml/sec vs 2.2 ml/sec before, so it's 5.6x
better!

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nielsbot
Putting the tube in the handle seems like a great design! Has anyone hit on
that before? (Happy New Year everyone)

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tobr
It’s a clever way to hide it. But wouldn’t it be better to just let it loop
around the handle, like this? [1]

1: Excuse the crappy drawing,
[https://i.postimg.cc/FR7Qc9M5/0845194-D-F5-DE-46-D6-8200-CB9...](https://i.postimg.cc/FR7Qc9M5/0845194-D-F5-DE-46-D6-8200-CB9-F8-ABDA332.jpg)

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nielsbot
oh yeah... that’s good too

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heyjudy
Nice.

Two phase flow is a difficult subject, so much so the owner of a nuclear
engineering consultancy I worked for wrote his magnum opus on it: _Two-Phase
Flow in Complex Systems_ It's imperative to get right in process environments
like chemical production facilities and nuclear reactors.
[https://www.wiley.com/WileyCDA/WileyTitle/productCd-04713296...](https://www.wiley.com/WileyCDA/WileyTitle/productCd-0471329673.html)

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jonsen
How is this relevant? Pouring liquid into a Pythagorean cup does not lead to
two-phase flow?!

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bmsleight_
Relevant, by only being link spam.

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klyrs
My grandpa had a similar contraption; a "puzzle jug" \-- he'd fill it with
wine, drink some, and pass it around to his guests -- who would often tip the
jug and spill. Amusingly, potheads are more likely to succeed than the general
population, because it's just a carburetor.

[https://en.m.wikipedia.org/wiki/Puzzle_jug](https://en.m.wikipedia.org/wiki/Puzzle_jug)

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szemet
I have one.

In my washing machine (LG) rinsing slot...

I know, because I always have to be very careful not to overfill it. But
usually there is some leftower water in its pipe so it does not keep the fluid
even if I not overfill - so nowadays I routinely take it apart and shake it
dry before each washing - clever but not to convenient...

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based2
[https://en.wikipedia.org/wiki/Hero_of_Alexandria](https://en.wikipedia.org/wiki/Hero_of_Alexandria)

[https://en.wikipedia.org/wiki/Heron%27s_fountain](https://en.wikipedia.org/wiki/Heron%27s_fountain)

