Introduction: Metropolis - Knex Ball Machine Elements and Lifts

Picture of Metropolis - Knex Ball Machine Elements and Lifts

Hello everyone,
I wanted to post a selection of elements that I used in my latest ball machine metropolis. I can't post all of them with step by step instructions. But you should be able to make most parts by looking at the pictures in this instructable.

Table of contents
Step 1: The Official Video
Step 2: Flat Spiral
Step 3: Spinning Basket
Step 4: Five Ball Basket
Step 5: Ball Seperator
Step 6: Rattling Stairs
Step 7: Free-fall Spinners
Step 8: Zigzag
Step 9: Catcher
Step 10: Halfpipe
Step 11: Red Double Spiral
Step 12: Two Ball Dropper
Step 13: Small Ferris Wheel
Step 14: Flexible Path
Step 15: Rollercoaster Path
Step 16: Quadruple Arm Lift - The wheel
Step 17: Quadruple Arm Lift - How to set up the wheel
Step 18: Wheel Lift - The base
Step 19: Wheel Lift - Middle part & Motor
Step 20: Wheel Lift - The top
Step 21: Fast Corner 

Feel free to comment, criticize or ask anything.

Thanks for looking and have fun building!


Step 1: Metropolis

If you haven't seen Metropolis, go to this link for the slideshow.
Or watch the video here:

Step 2: Flat Spiral

Picture of Flat Spiral

Here's the flat spiral, the ball will roll away from the center. It is very hard to get the orange track right. But it's also very cool to look at :)

Step 1: Make the frame

Step 2: Support the frame

Step 3: Add the track

Step 4: Make the ball's entrance
> I used this ball dropping mechanism

Step 5: Adjust supports and track width
> When you make the path wider, the ball gets more speed.

Step 3: Spinning Basket

Picture of Spinning Basket

I modified this from another instructable. The ball will enter the basket, spin 300° and then drops out of the basket onto the next path.

Credits for the idea go to "yardking"

Step 4: Five Ball Basket

Picture of Five Ball Basket

This basket releases five balls at once. You can adjust the weight by adding or removing wheels.

Step 5: Ball Separator

Picture of Ball Separator

When installed correctly this can be used to allow balls to pass one by one.

Step 6: Rattling Stairs

Picture of Rattling Stairs

These stairs make a rattling sound. Version one is with white rods and version two with blue rods.

Step 7: Free-fall Spinners

Picture of Free-fall Spinners

Spinning objects that can be used inside a support tower. 

Step 8: Zigzag

Picture of Zigzag

This is my favorite part of metropolis, the zigzag! 
In the video it is used in path 11 at 9:20.

When you make this, make sure the ball has some speed before it enters the zigzag. Otherwise it will not tip over.

Step 9: Catcher

Picture of Catcher

I used this to catch the ball after the zigzag element.

Step 10: Halfpipe

Picture of Halfpipe

This half pipe doesn't use a mechanism that drops the ball when it reaches the bottom, so it can be used in very narrow spaces. 

Step 11: Red Double Spiral

Picture of Red Double Spiral

A double spiral with a thick red edge. The center pieces are connected with an Y-connector (knex man hand). It is very heavy and needs to be supported well enough.

Step 12: Two Ball Dropper

Picture of Two Ball Dropper

It drops two balls at the same time...

Step 13: Small Ferris Wheel

Picture of Small Ferris Wheel

Step 14: Flexible Path

Picture of Flexible Path

A path made with flexible rods. You can also use normal rods for straight bits. It's quite fragile so make sure you support it enough!

Step 15: Rollercoaster Path

Picture of Rollercoaster Path

A fully customizable rollercoasterish path, you can make pretty much every kind of shape with this. It's also very sturdy, the ball rolls very well and that's what makes this path also very fast!

Step 16: Quadruple Arm Lift - the Wheel

Picture of Quadruple Arm Lift - the Wheel

The lift consists of wheels that have four long arms on it. I used one 12 Volt motor for two wheels. And connected the two wheels with a long chain.

Step 17: Quadruple Arm Lift - How to Set Up the Wheel

Picture of Quadruple Arm Lift - How to Set Up the Wheel

Right after you have made the wheels, it is time to install them in the tower.

You can put a motor directly on the main axle of the wheel, or connect multiple wheels together with a chain like I did. And then put a motor on the chain.

Step 18: Wheel Lift - the Base

Picture of Wheel Lift - the Base

I have cut the instructions for the wheel lift in three parts. The base, middle part and top part. You can make this lift as high as you want, and as fast as you want. But keep in mind that if you make it higher and faster, it will probably slow down when it carries over 3-4 balls at the same time.

The base is designed so that that the lift picks up balls one by one.

Step 19: Wheel Lift - Middle Part & Motor

Picture of Wheel Lift - Middle Part & Motor

Make it as high as you want. You can add the motor later on (I would put it somewhere in the middle).

Step 20: Wheel Lift - the Top

Picture of Wheel Lift - the Top

The orange track connecters can be replaced by yellow ones, depending on your choice of track you want to use.

Step 21: Fast Corner

Picture of Fast Corner

By making the corner very sturdy and adding an inclined plane, the ball will bounce against the plane and retain its speed!


knexgeek123 (author)2016-12-11

how long did that take to make its awsome

GrimEagle (author)2016-01-27


Linkin_J_Knex (author)2015-09-19

0_o How have I not found you before?! Subscribed xD

MegaMetal8 (author)2011-01-03

Can you post this one

Kairah (author)MegaMetal82011-01-04

Can't you make it from the pictures? It's not that hard, really... :P

www139 (author)Kairah2014-07-27

I built zigzag!

MegaMetal8 (author)Kairah2011-01-04

Yeh probably

www139 (author)2014-07-27

Since 2011, ball halves have gone up 3 cents!!! And that's in 3 years! Imagine what it will be like in 10 years!!

camodei (author)2014-05-09

It'd be awesome if you made a step by step instruction on how you made each piece and then put it all together. Hell...I'd pay for it.

yardking (author)2013-03-10

Thank you immensely for the credit!

firebombfury (author)2011-01-17

can you post the big ferris wheel??

Kairah (author)firebombfury2011-01-18

I already took it down but here's a large picture of it: link
here are a total of six white connectors in the center of it.

Fr-Pa-Co (author)Kairah2013-02-22

I built it but yours seems to spin faster than mine

cooljupjup (author)2013-02-20

he ik ben ook nederlands. heb jij fotos van het platform ?

OZKNEX22 (author)2013-01-18

wish i hade that much pieces

radknexman (author)2012-11-04

Im so using it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
=^..^= (cat).

Knexest (author)2012-07-05

Do you know if it works with the Black/White balls?

radknexman (author)Knexest2012-11-04


Knexest (author)radknexman2012-11-04

O.o Btw i tested this a while ago and they work on this :p

Leigo Andre (author)2012-02-08

Can you also use a big gear instead of 2 medium?

radknexman (author)Leigo Andre2012-11-04

try it

rrobinson1999 (author)2012-10-20

Do balls ever fall off the ball machine?

www139 (author)2012-10-10

Nice job I really like metropolis it has helped me come up with ideas for my ball machine!I don't need help with the path Deviders anymore I was able to make my own!

www139 (author)2012-10-03

hi I was wondering if you could give instructions on how to make your path deviders?I like them a lot!

Kairah (author)2012-09-02

Is anything else, besides the ball, touching the basket when the ball lands in it? Or is it off centre?

rrobinson1999 (author)Kairah2012-09-02

No, nothing other than the ball is touching the basket. Also, it is perfectly level. It seems like whenever the ball lands on it, it pushes the basket too far on one side causing the ball to fall off. I have tried many adjustments but nothing seems to be working.

Kairah (author)rrobinson19992012-09-02

Hmm, I'm not sure how it could go wrong then. Perhaps you could try to make the basket a little more stable by adding some weight to the bottom of the basket.

cubesquaredtothe1 (author)2011-06-14

Cool, I use that track a lot so that will help.


Oh god I haven't been on instructables in a long time haha :D Sometime last year.


I'll come back...been doing a lot of YouTube videos since I got an amazing computer :D

Fr-Pa-Co (author)2012-04-10

"Version blue with blue rods". I think you meant version two with blue rods

Kairah (author)Fr-Pa-Co2012-04-10

Yup, edited :)

Orangeprofessor (author)Kairah2012-04-17

Version blue sounds better

Fr-Pa-Co (author)Orangeprofessor2012-04-18

It probably does but I was just following the pattern. The coolest would be version white is with white rods and version blue with blue rods

Orangeprofessor (author)Fr-Pa-Co2012-04-18

Makes Sence

Fr-Pa-Co (author)Kairah2012-04-10

Cool, btw could you make the video so that you can watch it on iPod iPad and iPhone. I think you do it on settings from YouTube from your computer

firebombfury (author)2011-01-17

how do you build the middle panel in the tower? and how do you install them

Kairah (author)firebombfury2011-01-18

I just used a lot of white connectors instead of rods, to reinforce the tower.

firebombfury (author)Kairah2011-01-18

is the middle necessary??

Kairah (author)firebombfury2011-01-19

Nah, it's just for looks. You can just use a normal frame.

firebombfury (author)Kairah2011-01-19

every time i put the motor directly on the axle and turn it on, the wheel turns really really fast not like yours in the video, what do i do?

Kairah (author)firebombfury2011-01-19

You can reduce the speed with a small gear on the motoraxle and a large yellow gear on the wheelaxle.

firebombfury (author)Kairah2011-01-20


Leigo Andre (author)firebombfury2012-02-13

It also makex the strength of the motor bigger

I_am_Canadian (author)2011-10-26

On the wheel lift, is it necessary to have the one side made of solid snowflakes, or can both sides be made of the blue rod frame?

Kairah (author)I_am_Canadian2011-10-31

Sure, you can have it open on both sides. Also the remaining side does not need to be filled with snowflakes. If you replace half of those with blue rods, or 3/4th with red rods, it will probably still work!

I_am_Canadian (author)Kairah2011-10-31

Awesome, thanks very much!

But the snowflakes make it stronger and sturdier.

About This Instructable




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