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Marble Fountain

willmorrison.net

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Re: Marble Fountain

#81

Post by CobrastanJorji »

deaux wrote: post #79
stavros wrote: post #53

Earlier quoted context omitted.

A good use case for 3D printers is random, small, custom household items that greatly increase my quality of life, much more than it is a unique sculpture.

Really curious to hear a few of these!

I'll give you an example from my life. I got a set of cheap LED lights for a closet. They come with a little remote control to turn them on, but I didn't have a good place to put the remote control, so I made a little wall holster that's sized exactly to hold the little remote.

I also got one of those SimpliSafe home security systems. It came with a door sensor, but the sensor didn't quite fit our door frame. So I printed a tiny piece whose dimensions exactly matched the SimpliSafe and my door frame, so it allows the parts to meet up but doesn't look weird.

Of course, 99% of what I print is useless stuff that looked neat on Printables, but sometimes I make stuff that actually serves a purpose!

Re: Marble Fountain

#82

Post by [deleted] »

kazinator wrote: post #29

Designers of marble fountains who don't use computing to design the paths run into reliability issues: sometimes balls derailing out of their track. They have to observe the contraption, identify problems (balls getting jammed up or jumping out) and then guess at the root causes and make manual adjustments. That's the thing here: he has it running for hours presumably without any ball jumping out. Most of the tracks…

[deleted]

Re: Marble Fountain

#83

Post by jjcob »

kazinator wrote: post #29

Designers of marble fountains who don't use computing to design the paths run into reliability issues: sometimes balls derailing out of their track. They have to observe the contraption, identify problems (balls getting jammed up or jumping out) and then guess at the root causes and make manual adjustments. That's the thing here: he has it running for hours presumably without any ball jumping out. Most of the tracks…

You are missing inertia!

The state of each ball can be described by 9 parameters: the current location of the center of mass (x,y,z), the current linear velocity (vx, vy, xz) and the angular velocity on 3 axes.

I don't think the forces acting on the rails need to be similar -- they just need to be such that the acceleration of the ball is always parallel to the track. Unfortunately the equation of motion will look pretty ugly and optimizing the system will be quite a challenge.

And finally, the system has to be stable, ie. small perturbations should be cancelled rather than grow - if a ball gets a little too fast there should be something like a bend that slows it down, but that bend should at the same time not slow down a ball that is already too slow...

Re: Marble Fountain

#84

Post by jstanley »

gaudystead wrote: post #69
cissou wrote: post #64

Earlier quoted context omitted.

What printer do you use for that and are you happy about it?

I'm not the person you asked, but depending on what kinds of quality of life improvements you're looking for, your budget, your 3D design abilities, and your tolerance for working on the printer versus printing with it, the answer will vary in terms of what works for you. If you're casually interested, the Bambu Lab A1 combo will do most things you'd want it to do, fairly reliably, but with a closed ecosystem. If you…

If you want something more open source go for a Prusa. I don't buy that a Prusa is more robust than a Bambu.

I used to have a Prusa Mini and now have a Bambu X1C and it is a world of difference. I would never go back.

Re: Marble Fountain

#87

Post by bazzargh »

stavros wrote: post #52
sixtyj wrote: post #49

Earlier quoted context omitted.

My point was that these software could help to find weak parts in trajectory - so instead of trying to figure it out by looking where balls are too quick to fall from the ride - you can simulate it. I saw real tramway simulation done in Ansys.

I think the physics are different, a ball is basically a car without a differential, so it's going to behave differently on the tracks. I'd imagine the ball is harder to simulate because of that.

One of the results for hilbert curve marble tracks, mentioned elsewhere in the thread, was a video showing how to make one in blender, which has a physics engine so it can simulate it pretty well.

https://www.youtube.com/watch?v=8YeXyUNCnhM

I'd imagine that the 3d-printable models could be imported into blender, so it's 'just' adding balls and motion to the lift.

Re: Marble Fountain

#89

Post by worldmerge »

Will this is incredible! I’ve been learning openscad and making 3d models with it using python and this is such an inspiration. Check out the latest nightly version of openscad it’s significantly faster, like seconds vs multiple minutes on my exports.

Re: Marble Fountain

#90

Post by WillMorr »

adzm wrote: post #58
WillMorr wrote: post #35

Earlier quoted context omitted.

It's actually much weirder than that: banking changes the axis of rotation and thus kills the rotational inertia. The tracks bank super aggressively in order to prevent the ball from accelerating too much and hopping the track. This is part of why the descent is so smooth and all the balls move at more or less the same speed. Also to be fair the final system does lose a ball every 30ish minutes. The tuning was largel…

Does the temperature of the track change much after thirty minutes?

I haven't actually measured it but that's a good thought, I may borrow a thermal camera and do some testing! It's not noticeably warm to the touch but this functionally a system that converts potential energy into heat and sound so there's probably a measurable change.
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