Introduction: The Official Guide for Building Knex Ball Machines

About: Hi! I'm Ruben, better known as RNB. I'm a student Mechanical Engineering and hence like to build contraptions related to that. I mostly make use of K'nex, which is convenient to use since it is easy to design …

Hi!This is a collaboration between RNB, Shadowman39, and Tornado96.

This is our tutorial on how to make K'nex Ball Machines. It covers all parts of making and designing a ball machine, from the first sketches and ideas, to lifts, to the most advanced elements. Good luck with building yours, and post a picture of your ball machine!

Before starting, please take a look at these guides, to get an idea what you can do. Looking at ball machines from other users also helps a lot.

Enjoy! Feedback and/or suggestions for this guide are appreciated!

Step 1: Planning

Before you start building, you have to get an idea. Some of you might think now, "I'm skipping this part, it's boring," but we really advise you not to do that! It helps a lot when you start with a good idea. It also helps construction to go quicker and easier. Before starting to plan, read through the ENTIRE guide. Each step gives tips about the desinging, how to make your ball machine sturdy, interesting and more!

Planning the ball machine
Before you're gonna draw a ball machine on graph or normal paper, you must think about the following:
  • Do you want a big or a small ball machine?
  • What lift(s) are you going to use? See this guide for all lifts!
  • Do you want 1 or multiple Networks? (a network is a group of lifts in succession, one after the other)
  • Are there elements that you absolutely want? (see the guides listed at the intro page for links!)
  • Invent new parts to make it original.
  • Will your ball machine have a certain theme? (see Step 2 for more.)
  • Plan a scheme that shows which path start at which network and at which one it ends: you don't want 3 separate machines, so there must be paths leading to other networks!
Planning the ball machine on paper
Now design the ball tower in your head, and write/draw some stuff down. The first thing you'll want to plan for a ball machine will be the main tower structure. These are the main towers that give the ball machine its height and mass. You don't have to plan all of the towers; just the main ones.

Make sure that the lifts fit in on they way that they have to fit in! If you have a small ball machine, we suggest having towers with blue rods as boxes, and yellow rods for diagonal support. If you want a big one, we suggest towers with red and gray rods, unless you have enough pieces to make a blue rod tower.

Now you're going to draw your ball machine on graph paper. You can also draw it on normal paper, but graph paper is neater. A rough sketch can be drawn on normal paper. We suggest taking 1 square for each blue rod. It's the most useful to draw it in top view.

You don't have to design all of it before you build. You can write it down on paper as you go. But it is best to plan at least the tower structure on paper. Planning tracks and elements on paper first can be hard, because the ball machine is 3D, and your paper is 2D. Even if you draw it from all sides, it can get hard. Drawing big elements first, such as Ferris wheels, is useful, so you know where you'll place the big elements. The same goes for lifts and networks of lifts. But that can be planned out after you've got the main tower structure down.

Step 2: Theming

One of the questions we discussed is the theming. A themed ball machine brings a completely different challenge compared to a normal ball machine. Make sure you choose the theme of the ball machine BEFORE you start building.
Here's a list of things you will need to know before you start your themed ball machine:

1. Remember that theming uses a LOT of pieces.
2. Theming is difficult and you have to plan it out.
3. Plan out where you will put everything (eg. claw) and try to make it interact with the balls.

It is not possible to describe how you should make your theme: every time it will be different. Still we have some general tips to get started:

  • Look at real things, imitate them with K'nex
  • Use moving elements like this one as starting point. From such elements, build the scenery around it so that the ball interacts with it.
  • Do not theme your whole ball machine: just some parts makes it look cleaner, saves pieces and makes us able to see the ball go through the machine!

Step 3: Order of Construction

Before you're gonna build it, you have to know what the best order is of building your ball machine. You could think:"I'll start with the first lift and build more lifts, towers and track" but that isn't the easiest way, cause you have to modify the idea to make the lifts good. Underneath is the best order.

  • Sort your K'nex (terrible work, but it makes the construction go faster)
  • Make the base and main towers, using your sketch and plans. (step 4)
  • Make the lifts of the first Network and the towers that support it. (step 4 and 5)
  • Make the path-separators and paths of the first Network, including elements. (step 6 and 7)
  • Make the other Networks, if you want to. (step 8)
  • Make your model perfect, and publish it! (step 9)
You don't have to stick with this order, but this is a great order to build things in. If you want, you can build all of the networks first to get lifts out of the way, or build it network by network, including paths. But building the towers first is what you'll usually do, unless you build prototypes of lifts of elements first and wait to add them in.

Now go to the next step, and start building your base and main towers!

Step 4: Beginning Construction: Making Base and Main Towers

Let's start with the fun part! 
Building means you try something, which probably wan't work at first. Than it is important to keep trying, and to be creative. Often the basic supports will not fit or work, keep looking for solutions. It can help too to look at other ball machines which have a similar part in it, and than imitating that one.

Before building the lifts:
Firstly, you need to build a base. Make this using your sketch. A base can be flat, or 3D. 3D bases offer space to hide all the mechanics in, and a stronger base for supports, whilst flat bases cost less pieces. A combination is also possible, or even parts without a base. (just loose support on the ground)
After that attach the bottom parts of the towers on it. Look to the pictures to see how a tower/base should be made. After that you created the base, you should make the first lift. Go to the next step for that.

After/while building the lifts:
While building the lifts you should make supports to keep the lifts stable. After that you'll just finish the supports. When they're not stable enough, we suggest adding horizontal connections between towers. These can be used too for supporting lifts. See the pictures for how they look like.

Step 5: First Network: Lifts

A network is a bunch of lifts to bring the balls to the top of the machine. Using the lifts you want, and the instructions of them (or your own!) you can make the first lift. It is NOT necessary to have all lifts linked up, you can add a small track with a jump or loop in it for example, to make it look fun. It is the best to vary between fast and slow lifts, small and huge lifts to make it interesting. 

We recommend the first network to go to the top of your machine; other networks can stop half-way, but the largest one takes the most space, so that one should be build first.

Vertrical lifts (i.e. the spiral lift) can be placed in, or against the vertical supports. Lifts that are very wide (i.e. the Stair lift) should be placed on the horizontal supports, for stability. If there is no space left, make sure that the lifts are stable. 

A last thing you have to think off is the motor placement: you should be able to reach the switch without falling on the machine. When having troubles with that, use motors with a wire, so the switch can be on a place that is good reachable.

Step 6: First Network: Top

Now you're first network is ready to be completed! Depending on your design, a number of paths should start here. There are a few 'separators', which are listed below. It is also possible to start with 2 paths, add some elements, and to later split them up again. There are many choices how to divide the balls, so choose the one that fits your machine the best!

'The Official Guide to Knex Ball Machine Path Selectors' by mathsboy314
'Infinity switch' by Sorunome
'Horizontal path separator' by Darth Trainman
'Vertical path separator' - Seen in the picture below

Step 7: First Network: Paths and Elements

The best part of making your machine, the paths! Paths are very fun to make, but take a lot of time. Firstly, build the bigger elements that should be included, like a Wheel. Between the elements there must be connecting paths. Most elements can use all types of paths, but there are a few which require the orange path. The orange path can be made with yellow half-moon connectors too. The advantage of the orange path is that the ball can easily be aimed at certain spots, and goes faster. Turning is harder with them. It is the best to vary a lot between types of paths, to make it interesting.

The 2 links below show the most common used paths, but you can vary of course, or invent your own path style!
'Yellow pathing'
'Orange pathing'

Step 8: More Networks

Once you've finished the first network, you can eventually add more networks if you want. For doing that, re-do step 5/7. 

Step 9: Completing Model

Now that you've created all paths and lifts, you can still make improvements. Add a nice tunnel, some more theme, or improve parts that you aren't happy with. Improve until you think you've got the ultimate ball machine. After this: Congrats on finishing!

Now you should make a video about it, and put it on Youtube (or any other site). You could use programs like Imovie, Windows Movie Maker or Adobe Premiere Elements for making the video. After that, take pictures, and put it on this site!

We'll add your pictures to this step when you send them to us, we'll like to see what you've made!

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