Introduction: String Fountain

Picture of String Fountain

The challenge, how does one present 50's synchronized swimming, or water works like the Bellagio fountain in Las Vegas, without water. Pushing string with a motor is not a new idea. Adding servo motors and a microcontroller to create automated and interactive installation is what I was looking to do during my residency at Autodesk's new facility on Pier 9.

This Instructable goes through the assembly of one of my 1/4 scale string fountains. The second image above is 6 string fountains arraigned in a circle moving string though the air.


Step 1: The Parts

Picture of The Parts

Here they are all laid out. Always be knolling, or so they say.

I've attached a .zip file with all the STL files. I printed all the parts except for the base on an Objet Conex 500. The base plate was laser cut out of 1/8" acrylic.

McMaster Carr parts.

16pcs - 94150A305 - M2 Stainless Steel Nuts

4pcs - 90116A009 - M2 X 5mm Philips Head Machine Screw

6pcs - 90116A010 - M2 X 6mm Philips Head Machine Screw

10pcs - 90116A015 - M2 X 8mm Philips Head Machine Screw

3pcs - 90116A113 - M2.5 X 10mm Philips Head Machine Screw

4pcs - 90116A114 - M2.5 X 12mm Philips Head Machine Screw

3pcs - 90116A1531 - M3 X 8mm Philips Head Machine Screw

1pc - 90263A1165 - Shoulder Screw, 3mm Diameter X 8mm Long Shoulder, M2 Thread

1pc - 1265K311 - Metric Miniature Type 316 Ss Drive Shaft, 3 Mm Od, 200 Mm Length

3pcs - 7804K1249 - 3M X 6M X 2.5M Stainless Steel Bearing

3pcs - 7804K1269 - 3M X 8M X 4M Stainless Steel Bearing

36pcs - 96415K693 - 316 Stainless Steel Precision Ball, 3/32" Diameter

Tower Hobbies

1pc - LXXJW4 - Great Planes Rimfire 250 Outrunner Brushless Motor

1pc - LXKSY2 - Great Planes Silver Series 8A Brushless ESC 5V/1A BEC

1pc - HMXE7625 - Heli-Max Pro Linkage Set MX400

2pc - LXLGJ5 - Hitec HS-65MG Mighty Metal Gear Feather Micro Servo

Step 2: Attaching the Secondary Servo to the Servo Assembly

Picture of Attaching the Secondary Servo to the Servo Assembly

Gather the part for this step.

Slip the nut into the nut slot.

Thread the servo wire through the back of the servo bracket.

Tilt the servo so the wire exit is inside the servo bracket.

Gently tilt the top of the servo into the servo bracket.

Slip a nut into the nut pocket.

Secure the servo to the servo bracket using the screws.

Step 3: Attaching the Primary Servo Horn to the Primary Servo

Picture of Attaching the Primary Servo Horn to the Primary Servo

Gather the parts for this step.

Push the nuts into the nut slots.

Rotate the servo to find the center of travel.

Secure the servo horn to the servo with the screw.

Step 4: Attaching the Primary Servo to the Servo Assembly

Picture of Attaching the Primary Servo to the Servo Assembly

Gather the parts for this step.

Thread the servo wire though the back of the servo assembly.

Slip the servo into the servo pocket.

Press the nuts into the two nut pockets.

Secure the servo to the servo assembly with the screws.

Step 5: Building and Assembling the Secondary Servo Horn

Picture of Building and Assembling the Secondary Servo Horn

Collect the parts required for this step. Note the servo ball and the black screw are part of the servo linkage kit.

Push the nut into the nut pocket on the servo horn.

Slip the screw into the servo ball and tighten onto the servo horn.

Adjust the servo so that you're attaching the servo horn in the middle of it's travel.

Secure the servo horn to the secondary servo as shown in the last image.

Step 6: Building and Attaching the Rear Bearing Assembly

Picture of Building and Attaching the Rear Bearing Assembly

I decided to use a second bearing on the primary servo. It stiffened up the design quite a bit.

Gather the part for this step.

Push the nuts into the nut pockets.

Press the shaft into the rear support.

Press the bearing onto the shaft until it is flush with the shaft.

Now press this assembly into the back of the servo assembly as shown in the last image.

Step 7: Assembling the Base and Attaching the Servo Assembly

Picture of Assembling the Base and Attaching the Servo Assembly

Gather the part for this step.

Mount the feet on the base. The base is symmetrical so you can mount the feet on either side.

Mount the servo assembly to the base.

Step 8: Building the Rotor

Picture of Building the Rotor

This is the assembly that 'pushes' the string. I used an outrunner motor so I could hide it in this assembly as opposed to having it stick out the side of the String Fountain.

Gather the parts for this step.

Press the motor rotor into the back plate. Note the location of the holes in reference to the motor rotor. Do your best to line them up.

Press the front plate onto the motor rotor.

Secure the front and back plate together with the screws.

Step 9: Building the Stator

Picture of Building the Stator

Gather the parts for this step.

Feed the motor stator wires through the slot shown in the second image.

Press the motor stator on the spud. Note the exit location of the wires and do your best to line them up.

Press the bearing into their pockets.

Press the nuts into their nut pockets.

Step 10: Assembling the Stator and the Rotor

Picture of Assembling the Stator and the Rotor

Gather the parts for this step.

Slide the rotor assembly into the stator assembly.

Attach the shaft clip onto the shaft.

Step 11: Building and Assembling the Idler Wheel

Picture of Building and Assembling the Idler Wheel

Gather the parts for this step.

Press the bearing into the idler wheel.

Press the lock nut into the nut pocket.

Slide the shoulder bolt into the bearing on the idler wheel and secure to the stator housing.

Step 12: Building and Assembling the Slew Bearing

Picture of Building and Assembling the Slew Bearing

This part of the design proved to be the most difficult to design. I wanted to keep the cross section narrow. Adding additional bearing to the motor assembly meant they would be spinning at the speed of the motor and feeding back into the servo assembly. After a bit of experimenting I ended up with this design for the slew bearing. Here's the proof of concept, 3d Printed Bearing.

Gather the parts for this step.

Push the nut into the nut pocket.

Slide the screw through the servo linkage ball.

Secure the servo linkage ball to the bearing retainer.

Place the slew frame over the motor assembly.

Roll the bearings in. This is way more fun than you can imagine.

Place the bearing retainer over the bearing.

Secure the bearing retainer with the screws.

Step 13: Connect Drive Assembly to Position Assembly

Picture of Connect Drive Assembly to Position Assembly

Gather the parts for this step.

Feed the wires for the motor controller through the servo assembly, as shown in image 2

Feed the wires through the slew frame, as shown in image 3.

Use the screws to secure the slew frame to the servo assembly but don't them tighten yet.

Adjust the wires so they are equal in length and lay flat between the slew frame and the servo assembly.

Connect the motor wires to the motor controller wires.

Adjust the motor controller wires until you have enough wire to allow the motor assembly to move up and down with out straining the wires.

Take up the slack and then tighten the screws.

Step 14: Secure Motor Controller

Picture of Secure Motor Controller

Slip the remaining motor controller wires through the servo assembly where the servo wires exit.

Slip the motor controller into the notch provided above the secondary servo.

Step 15: Thread String and Secure Cover

Picture of Thread String and Secure Cover

Gather the parts for this step.

Slip the string between the motor rotor and the idler wheel. Just like flossing your teeth.

Rest the string in the string entrance and the string exit.

Press the bearing into the motor cover.

Place the motor cover over the motor assembly.

Secure the motor cover with the screws.

Step 16: Secure String Guide

Picture of Secure String Guide

Gather the parts for this step.

Place the string guide in the string guide notch.

Secure the string guide with the screws.

Step 17: Attach Servo Linkage

Picture of Attach Servo Linkage

Gather the parts for this step.

Snap the servo linkage onto the servo balls.

Step 18: Double Check Your Fasteners

Picture of Double Check Your Fasteners

Make sure all your fasteners are tight. After you're happy with the assembly go back through and use blue Locktite on all the fasteners. The String Fountain has been known to vibrate a screw loose from time to time.

Step 19: Connecting a Microcontroller

Picture of Connecting a Microcontroller

I'm using Pololu's Maesto series of motion controllers to control my string fountain. You would only need their micro model to control one string fountain. You can also use an Arduino or any other microcontroller that can PWM RC servos.

Step 20: Video

Here's a video of a string fountain, enjoy.


audreyobscura (author)2015-01-15

This project is amazing. Lovely to watch, brilliantly created - your mind is a marvel, and I love reading about your process.

jan.dornig made it! (author)2016-03-19

in progress of making it - simplified version with help of paolo!

the 3d printing is very rough and the motor underpowered but you can see it´s starting to go in the right direction

howardjackson (author)2015-04-02

Great work

davidramirez5 (author)2015-04-01

Great display ..Really good work

earlcollins (author)2015-03-28

Wooowwwww....Amazing Creativity!!!

ongara_01 (author)2015-02-21


JohnnieT (author)2015-02-19

Really nice!!

mhaeg (author)2015-02-04

Can you help with a base measurement I should be following when sending the STL files to the 3d printer?

Salvagione (author)mhaeg2015-02-04

All the parts were modeled in inches.

macrumpton (author)2015-01-19

Do you think there is any way to reduce the noise?

Salvagione (author)macrumpton2015-01-19

Yes, but for ~10x the cost. The RC motors with controllers cost ~$90 each. Maxon motor and controller cost ~$1500 each.

helipr0 (author)Salvagione2015-01-31

why not try cheap china made motors and esc's?

macrumpton (author)Salvagione2015-01-20

I wonder if you could propel the string with compressed air, eliminating motor, bearings and wheels, and maybe even the noise (with a remote compressor).

Salvagione (author)macrumpton2015-01-20

I thought about that. It's nosier and you have a condensation problem, the nozzle cools as the air exits and water condenses on it.

agis68 (author)2015-01-27

amazing job and creativity.....

Chamburn (author)2015-01-22

I am looking to make a mini version of the dancing but not as complicated as the bellagio fountain and what I am interested is that the materials you've used, are they the same as they do not appear waterproof?

Salvagione (author)Chamburn2015-01-22

Chamburn, that's a different project. I designed the string fountain to create a fountain like effect without water.

Chamburn (author)Salvagione2015-01-22

Ohh okay, But I really like the way that the servo is used to control movement and hopefully I can use it to control the movement of the pump and lights for the added effects....

Greasetattoo (author)2015-01-22

Awesome, great job!

sebastien.noel.7773 (author)2015-01-21

Very nice. I like the colours you introduced in the string and the tilting movement. We made something similar some years ago. Have a look at this one , slightly scaled up ;-)

You can see it running here:

Antzy Carmasaic (author)2015-01-20

So beautiful and trippy!!!

macrumpton (author)2015-01-19

One of my most treasured childhood memories is of going to a NYC MOMA exibit in the 60's of kinetic sculptures. I believe they were the work of Jean Tinguely a Swiss artist. One of them was a string fountain that used a ribbon loop that was at least 30ft long and it was very dramatic as not only did the loop rise and fall but the machine rotated on the vertical axis so that it swept a giant circle in the air as the ribbon writhed like a living thing. There was also a giant noisy machine that tossed soccer balls across the gallery and caught them and routed them back to the throwing end.

Salvagione (author)macrumpton2015-01-19

mcrumpton, How lucky you are. I would have loved to see that show. I have the show catalog and it's beautiful. I saw the ribbon piece a few years ago at the Museum Tinguley in Basel. It's an amazing piece. I've always wanted to see Rotozaza No. 1 in person.

Jan_Henrik (author)2015-01-13

Video Request!!!

gravityisweak (author)Jan_Henrik2015-01-13

+7 (or animated gif would do nicely too!)

Salvagione (author)gravityisweak2015-01-15

I've added an animated gif as the first image, thank you for the suggestion. Video next.

Le Gui (author)Salvagione2015-01-19

Thanks for the gif and video.

Great effect, that's impressive!

SanjayDubey (author)Jan_Henrik2015-01-18

hey jan, you can find a clip in the pier 9 promotional video..

PRO DR MR BOB (author)Jan_Henrik2015-01-13


Victor Does (author)Jan_Henrik2015-01-13

Yes please!

periprohus (author)Jan_Henrik2015-01-13


dr_peru (author)Jan_Henrik2015-01-13


Le Gui (author)Jan_Henrik2015-01-13


dpecile (author)Jan_Henrik2015-01-13


mlduffy (author)Jan_Henrik2015-01-13


samalert (author)Jan_Henrik2015-01-13


ShrickSon (author)2015-01-18

I like this, and as an rc enthusiast, I already have a lot of the stuff to make one. I'll just modify it a little bit to work with my transmitter/receiver because I like things to be a little more interactive. Thanks for this!

Salvagione (author)ShrickSon2015-01-19

ShrickSon, I'm indebted to the RC world, the size and pricing of servos and brushless motors made this project possible. If I had to do this with Maxon motors and controllers it would have been an order of magnitude more expensive.

madvic (author)2015-01-19

How did you craft the plastic pieces? Maybe another instructable for that? Congratulations

Salvagione (author)madvic2015-01-19

Madvic, I used CAD software to model the parts and then printed them on a 3d printer. An instructable on my design intent might be interesting, where as an instructable on how to use CAD would be book sized.

CrayfishYAY (author)2015-01-18

So what's the price of all these parts? Like what's the total cost of all you have to buy?

SanjayDubey (author)2015-01-18

hello sir, I was really impressed by your 'string fountain' the very first time I saw it in the pier 9 promotional video. To find it I first searched each and every name in the credits, then I searched each person on the internet, then after a time I found your page on instructables. Then I searched for 'string fountain' but it was no where to be found. There was only a servo instructables. I got sad and sat down to make my own with the speed of the feed of the string I thought it to be a brushless... started to design a case to fit all the stuff with drive gear... then got busy into some other stuff and suddenly in today's instructable newsletter I found the woderful 'string fountain'. I thank you sir for this instructable and promise to inform you the time I'll upload my version. :)

Salvagione (author)SanjayDubey2015-01-18

hunter9t9, keep me posted. If you get stuck ping me and I'll help where a can.

askjerry (author)2015-01-18

That was very impressive. The engineering you did to get all the components to be as small, light, and functional as could be was incredible. I love your attention to detail. Awesome project! Awesome instructable!

jims212 (author)2015-01-18

That looks very cool. Thank you

mopsiok (author)2015-01-18

Cool effect and very well documented, thanks for sharing!

syedrezaali (author)2015-01-15

Super inspirational work Paolo! +infinity

charlessowers (author)2015-01-15

Hi, cool project. Have you seen the exhibit I made in 1999 just next door to you at the Exploratorium? You must have seen the bicycle Rope Squirters outside? Some details are here including the toy version that uses the same string...

also a fun video of Nobel Prize physicist Leon Letterman trying to explain it in 2001 here

Original inspiration was from Clifford Wagner and Norm Tuck's Lariat Chain that is also on display here at the Explo.

Bruce Shapiro ( made a stepper actuated computer controlled device like yours sometime back in 2004 or so but I cannot find anything online about it. Just FYI.

Salvagione (author)charlessowers2015-01-15

Charles, your 1999 exhibit is the inspiration for this work. I first saw it in the early '00 at the old exploratorium. The bicycle rope squirters, while good at wearing out kids, don't hit me the same way your 1999 piece does. By the way the earliest example I've found of this work is in the Art & Metier museum in Paris, ca.1860's.

I'd love to know more about the Shapiro piece as that's where I'm going with this work and it's always nice to know the terrain.

I have a half dozen of these 1/4 scale String Fountains up and running. I've been playing with routines from 50 synchronized swimming and automated water fountain routines a la the Bellagio.

I also have a version what shoots a 3/4" rope 16' into the air that's where I'd like to take this work. Out of the 'toy' 'science' space into the architectural space. Love to talk more but the 'about' section of your website doesn't go anywhere.

About This Instructable




Bio: I am organic computer running poetic software. Interested in overlaps and antipodes. Fascinated by how metaphors shape our thoughts and objects. I've been wondering ... More »
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