
Towards a Better Pythagorean Cup - jstanley
https://incoherency.co.uk/blog/stories/pythagorean-cup.html
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walrus01
For anyone thinking of buying a 3D printer, there's some pretty decent options
that don't cost a ridiculous amount now... I have no financial interest in any
of these manufacturers or vendors, just passing on what's been reported to be
good quality by various people.

At the cheaper end of the scale there is the Alfawise U30 which is $175 + $20
shipping from china:
[https://www.google.com/search?client=ubuntu&channel=fs&q=u30...](https://www.google.com/search?client=ubuntu&channel=fs&q=u30+3d+printer&ie=utf-8&oe=utf-8)

Then there is the Creality CR-10S (note the S, not the original CR-10 model)
which is $369
[https://www.google.com/search?client=ubuntu&channel=fs&q=cre...](https://www.google.com/search?client=ubuntu&channel=fs&q=creality+cr-10s&ie=utf-8&oe=utf-8)

Search for either of those on youtube and you'll see some example setup and
test print videos.

The U30 is very new so a lot of the test/setup videos are in French or
Italian.

For people who want to try printing something really big, there's a
500x500x500mm capable version of the CR-10S which is called the CR-10S5, which
sells for around $629. Lots of videos on youtube of the output from that. It's
not supremely high quality in terms of print, like you would get from a $3500
500mm size 3D printer, but it's also a tiny fraction of the price.

~~~
oh_sigh
Also, unless you have big plans for an in-home 3d printer, there is nothing
wrong with getting access to one via a friend, coworker, library, or maker-
space and essentially just paying for filaments. I wouldn't be surprised if
in-home 3d printers sit idle for 95+% of the time.

I was about to drop about $1000 on one for some hobby projects, but then found
out my local library had a $6000 machine which I could use for essentially
free(I'd be paying for filaments regardless), so long as I scheduled my prints
a week in advance.

~~~
StavrosK
This is both very true and a bit false. My 3D printer sits idle more than 95%
of the time, but I just _could not have_ done what I do unless I had one right
next to me so I could iterate quickly. I usually need to do 4-5 iterations of
something to get all the tolerances and details right, which cannot be
scheduled a week in advance.

However, if you can share a printer with someone and have low-latency access
to it, definitely do not buy your own, just use that.

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dahart
> The handle looks rather contrived

Maybe you could stuff a dozen flat little drain pipes all the way around the
walls of the cup, in addition to or as an alternative to routing through the
handle. That way the handle could be petite and unsuspicious. Would that be
harder to reliably print?

~~~
jstanley
I actually wanted to do this, and went as far as drawing a sketch on paper,
but then I realised it would be impossible to drink from :).

As soon as you tilt the cup towards your lips the nearest tubes would fill up
and start siphoning.

~~~
dahart
That is a really good point that didn't occur to me.

So, how about winding all the tubes together around the cup in a spiral? That
would keep the high point always above the liquid line, unless the cup is
sitting flat when over-filled, wouldn't it?

~~~
jstanley
What a great idea. That seems like it would work!

The high point of each siphon could be exactly opposite the entry point.

The siphons would need to cross past each other, but only 2 at any one point
need to cross, which I think is manageable.

Maybe my Pythagorean cup rabbithole is still not over...

~~~
dahart
> Maybe my Pythagorean cup rabbithole is still not over...

I'm sorry! ;) And I will love to see it printed and/or turned into another
post.

~~~
jstanley
On second thoughts, I still don't think it would work.

As you tilt the cup towards your lips, if the "highest" siphon pickup is still
submerged, then that will correspond to the "lowest" siphon top and it will
start siphoning anyway.

It would work as long as it could be arranged that the pickup would become
exposed to air before the siphon started siphoning, but I'm not sure that's
possible while still retaining the property that it self-starts when
overfilled.

Also, even if the tube doesn't siphon because the pickup is exposed to air,
there would still be liquid in the tube, some of which would get pushed over
the top and leak out the bottom whenever you try to drink.

~~~
rhn_mk1
Connect them with a ring around the top. The high point will always be above
the liquid level while drinking.

~~~
jstanley
Nice, that would stop the siphon from self-starting!

Although it still wouldn't stop some water from trickling out the bottom when
it tips over the "lowest" peak.

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tejtm
I wonder if the flow could be improved by smoothing the inside of the siphon
tube, perhaps pumping a mild solvent through at high velocity for a little bit
would streamline the interior surface. As it is each printed layer is apt to
contribute some turbulence.

~~~
justtopost
In automotive racing where standard porting is verboten, an abrasive slurry of
a gritty putty consististancy is pumped through at pressure to smooth the
transitions. I think ford even used it for a few performance manifolds.
Commonly called extrude honing.

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

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jacknews
Another here:
[https://www.thingiverse.com/thing:257680](https://www.thingiverse.com/thing:257680)

Always good to have choice.

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siliconc0w
I think the point of the cup was that you wouldn't overfill it with wine
without losing it in your lap thus encouraging moderation. A pythagorean mug
doesn't quite make sense.

~~~
alanbernstein
Is coffee not worthy of moderation? Is there something wrong with drinking
alcohol from a mug?

~~~
jelly_dev
Best way to get ready for work in the morning

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peter_retief
I would love to find some sort of application for the p-cup (Besides pranking
people that is) Maybe a cistern with less moving parts, indoor irrigation, pet
water dispenser Should maybe make an "ask HN" ?

~~~
TeMPOraL
Flush toilets are a very well known and popular examples of p-cups. The toilet
bowl has a siphon built-in, which drains the bowl with its contents when the
water reaches high enough level.

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adityapurwa
I still don’t understand what is the purpose of having such a cup, wouldn’t it
just waste the water or used to limit the amount of water?

Anyone could help me, what is the usage and purpose of P cup?

~~~
andrewflnr
It's pretty much entirely a cool trick and a joke. It was framed as a social
commentary on gluttony, but I doubt that was ever the real reason for it or
taken seriously in any way. It's just a cool thingy.

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nielsbot
Great follow up.. Thanks.

