Knex Alternating Arm Lift




About: I'm a 16 year-old guy who loves to build mechanics out of knex. my main interests are ball machines and roller coasters. My real name is Matt and I'm a christian. I live in Australia or more commonly known a...
Hey Peeps! Tornado96 and Shadowman39 are proud to present our first collaboration: the Alternating Arm Lift!

This lift uses the concept behind Shadowman's Alternator Lift. However, the "alternators" are attached to arms, making it transport the balls a lot quicker. It also has concepts found in the stepper lift (the see-saw at the top).

Our goal for this lift was to make a fast, piece efficient lift and we think it came out pretty well! We hope you enjoy building it as much as we did!

This lift introduces a new instruction format: there are steps that give instructions on modules, which can be added to the middle of the lift to make it taller. See Step 8 for more information about the modules.

This lift works with the newer balls and the original balls.

Here's a video of the lift in action:


We know you guys want to get building, so how about we get started! Woah, not so fast... You need pieces first! :-) The next step is the piece count. 

Step 1: Piece Counting Time!

Here's all the pieces you'll need to build the alternating arm lift. Note that the pieces are named after their classic colors.

Rods: 363

green- 42
white- 74
blue- 98
yellow- 60
red- 65
gray- 20

Connectors: 295

dark gray- 51
light gray- 21
red- 25
green- 24
yellow- 53
white- 16
orange- 30
purple- 49
blue- 20

Other: 89

Y clip- 7
tan clip- 12
blue spacer- 39
silver spacer- 20
blue gear- 2
red gear- 2
small wheel- 3
small tire- 3
motor*- 1

Total: 747

And, of course, you'll need balls. 

*Newer-style motor. The one we used in this Ible is the green one; keep in mind that motors of other colors go different speeds. For example, the black one goes slowest and silver goes fastest.

Step 2: Base

To begin, build the base. Believe it or not, a base is essential to prevent unwanted collapse. There are two sections that will be attached at the end of the step.

1- Build the first section.
2- Build the second section.
3- Attach them together.
4- Close-up of the bottom.
5- Another close-up of the bottom of the other side.

Step 3: Entrance Track

Now complete the base by building the entrance track section. Otherwise, how would the balls enter the lift?

1- This will be part of the base.
2- Build this bit.
3- Another view.
4- Now attach those two sections together.
5- Entrance track! So exciting, isn't it?
6- Another view.
7- This thingy will support the track.
8- Connect it to the track.
9- Put the track on the tower section. There are two places where rods go in the holes of the connectors, and the support for the track connects to a yellow connector at the bottom.
10- Close-up of the track support.
11- View of other attachments (well, technically they aren't actually attachments, but oh well...)
12- The other side of the tower.
13- Close-up.
14- Now attach that section to the rest.
15- Another view.
16- Another view.
17- Get what you built in the last step and combine the sections to complete the base!
18- Another view.

Step 4: First Arm

This is the first of the four arms that you will build. 

1- Build this. If you don't, a creeper will blow up what you've built so far.
2- Grab four yellow rods.
3- Attach them to what you built in the first picture.
4- This is the other end of the arm.
5- Another view.
6- Attach it to the arm.
7- Another view.
9- Attach DA CLAW! to the rest of the arm.
10- Red things (f you're building with classic colors).
11- Connect them to the arm.
12- Another view.
13- Another view.
14- Now get the base and attach the arm to it to complete the step.
15- Another view. 
16- Another view.

Step 5: Tower

The next arm will be attached to this tower. After you build it, combine it with the base. And then your tower will be one red rod higher than before!!!!! How awesome is that! :-D

1- One side of the tower.
2- The other side.
3- Now attach them together.
4- Combine it with the base. 
5- Another view.
6- Another view.

Step 6: Second Arm

Now it's time to build arm number 2. Notice that this arm is different than the first arm (the claw is thinner). It may look extremely similar but for it to work the arms are different on either side of the tower.

1- Build this.
2- Get 4 yellow rods.
3- Connect the yellow rods.
4- Build this part.
5- Another view.
6- Connect it to the rest of the arm.
7- This is part of the claw.
8- Another view.
9- Another part of the claw.
10- Complete the claw.
11- Put it on the arm.
12- Build these.
13- Complete the arm.
14- Another view.
15- Get the rest of what you have built so far, and attach the arm to it. 
16- Another view, showing the attachments to the structure.
17- Another view.

Step 7: Lateral Supports

These supports will keep the lift stabilized. If you already built or plan to build other towers supporting it (which we recommend if you make it taller), you may be able to skip this step. Once again, this step will help to prevent collapse! It may be what saves your creation from younger siblings.

1- One of the supports.
2- Build 4 of them.
3- Attach them to the base.
4- Another view.

Step 8: Module Construction: Steps 9-12 (Optional)

So you've built the base... right? have you? are you sure? Ok you're sure, but are you positive you did? You may want to double-check.

Steps 9 to 12 will show you how to build the modules that allow this lift to be made higher. To make your lift taller you need to build more modules. If you don't want it go any higher than what the intro pictures showed, then skip these steps and go on to step 13. :-)

But if you do want to make it higher (come on, we know you do) then the following steps will show you how. Keep in mind that the higher it goes, the more the motor will strain due to the weight of arms combined. If you go any higher than one module you may need to use a stronger motor such as the electric motor. We will now provide the piece count for one module. For every module you build you will need another set of the pieces.


green- 8
white- 7
blue- 22
yellow- 14
red- 24
grey- 8


dark grey- 20
light grey- 8
red- 0
green- 6
yellow- 12
white- 4
orange- 8
purple/grey- 16
blue- 0


blue spacers- 4
silver spacers- 4

Total: 165

Step 9: Module: Tower (Part 1 of 2)

This is the first tower section of the module (there are two sections). 

1- Build one side.
2- Build the other side.
3- Attach them together.

Step 10: Module: First Arm

Now you'll build the first arm of the module and complete the first tower section.

1- Build this.
2- Get 4 yellow rods and attach them like so.
3- Build this.
4- Another view.
5- Attach them.
6- Build the claw.
7- Connect it to the arm.
8- Build these.
9- Connect them to the arm.
10- Another view.
11- Attach the arm to the tower you built in the last step.
12- Another view.
13- Another view.

Step 11: Module: Tower (Part 2 of 2)

As the title says, this is the second and last part of the tower of the module.

1- Build one side.
2- Build the other side.
3- Connect them together.
4- Attach Part 2 of the tower to the rest of the module.

Step 12: Module: Second Arm

This is the last part of the module. Remember, to make the lift even higher, you'll have to repeat Steps 9-12.

1- Build this.
2- Get 4 yellow rods and connect them.
3- Build this.
4- Another view.
5- Attach it to the rest.
6- Build part of the claw.
7- Another view.
8- Build the other part of the claw.
9- Connect the two parts together.
10- Attach the claw to the arm.
11- Build these.
12- Connect them to the arm.
13- Another view.
14- Connect the arm to the rest of the module. You are now finished with the module!
15- Another view.

Step 13: Lower Top Section

This is the tower that holds the last section of arms. 

1- Build one side of the tower.
2- Build the other side.
3- Combine them together.

Step 14: Third Arm

If you didn't build any extra modules, then this is the third arm. If you did build more modules, ignore the step title. :-P This arm is special since it is the top of one side of arms. 

1- Build this.
2- Build this.
3- Attach the two bits together.
4- Get two yellow rods and build the bit at the right.
5- Attach the rods and other bit to the rest.
6- Build the end of the arm.
7- Another view.
8- Connect it to the arm.
9- You know what this thing is, right?
10- Attach it to the arm.
11- Build these.
12- Connect them to the arm.
13- Close-up.
14- Get the tower section you built in the last step and attach the arm to it. Don't combine this section with the rest though, that will be for a later step.
15- Another view.

Step 15: Middle Tower Section and Small Arm

This tower section has a small arm on it. This arm doesn't carry the balls though, it just helps support the arms beneath it. 

1- Build this side.
2- Build the other side.
3- Connect them together.
4- Build part of the small arm.
5- Another view.
6- Build the other part of the small arm.
7- Attach the two sections together to complete the small arm.
8- Connect the arm to the tower.
9- Another view.

Step 16: Last Arm and Tower Combining

This is the last arm that will lift the balls to the exit point. After you attach it to the tower you built in the last step, get the tower section from Step 13 and 14 and combine them with the rest of the lift.

1- Build this.
2- Build one end of the arm.
3- Attach those.
4- Get 4 yellow rods.
5- K'nect them to the arm bit.
6- Build the other end of the arm.
7- Another view.
8- Attach it to the rest of the arm.
9- Start on the claw.
10- Another view.
11- The other part of the claw.
12- Connect those two parts.
13- Attach the claw to the arm.
14- Another view.
15- Build these.
16- Connect them to the arm.
17- Another view.
18- Attach the arm to the tower section you built in the last step.
19- Close-up of the arm's attachments.
20- Now get what you built in Step 13 and 14.
21- Combine them. The section with the small arm should be on top.
22- Another view.
23- Put that section on the rest of the lift. It's getting taller now!
24- Close-up.
25- Another view.

Step 17: Top Tower Section

This is the last tower section that goes at the top. It also holds the exit track.

1- Build one side of the tower.
2- Build the other side.
3- Connect them together.
4- This complicated contraption will push the ball out of the last arm.
5- Connect it like so.
6- Build this.
7- Connect it to the tower.
8- Another view.
9- Attach the top to the rest of the lift.
10- Another view, showing the connections.

Step 18: Exit Track

As the title says, this is the exit track. Without it, the balls will fall to their death! :-O Help save our little friends!

1- Build the track and the two small supports.
2- Attach the supports to the track (well they aren't really attached but oh well)
3- Another view.
4- Attach the track to the tower.
5- Another view.
6- Another view.

Step 19: The Power Complex

This is the gear section and motor, and crank. Being the most complicated part of the lift, pay close attention to the spacing and the gear placement. Once you're done test and make sure the crank actually rotates. :-)

1- Build this.
2- A view of the crank.
3- Another view.
4- Build this gear section.
5- Another view.
6- Another view.
7- Attach the two gear sections.
8- Build the stuff onto the motor. It is recommended that batteries are installed before you put the motor in.
9- Attach the motor to the gear section.
10- Another view.
11- Build this support.
12- Connect it to the motor/gear section.
13- Another view.
14- Build this.
15- Another view.
16- Attach it to the motor/gears.
17- Get a tan clip.
18- Connect it to the end of the blue rod.
19- Attach the motor/gear section to the top.
20- Another view.
21- Another view.
22- Yet another view.
23- And yet another view!

Step 20: See-saw

No, this isn't playground equipment... The see-saw is the thing that will make each side of arms move up and down, and it will connect to the crank. 

Note: This see-saw is NOT suitable for little kids.

1- Build these.
2- Build this.
3- Another view, showing the blue spacers.
4- Combine those three things.
5- Build this.
6- Attach it to the end.
7- Build this.
8- Attach it to the other end.
9- Build this.
10- Attach it to the other end.
11- Get a blue rod from the top of the tower.
12- Slide the blue rod through. Make sure it's in the right set of yellow connectors!
13- Another view.
14- Attach the see-saw to the tower and crank.
15- A view showing the crank.
16- Another view.
17- Another view.

Step 21: Rods of Control

You're almost done! These connect the see-saw to the arms. If you forget these, the lift might fail. But that's just a small chance.

1- Build these.
2- Connect them to the lift.
3- Another view.
4- Another view.
5- Guess what this is? Another view!

Step 22: You're Done! YAY!

Congrats, you have completed the Quest of Alternating Arms! You're reward:
A pat on the back and a job well done!

Kudos to you for finishing without creepers blowing it to smithereens.

Turn the motor on, load the balls and watch your creation come to life!

Troubleshooting: If the balls are falling out when they transfer from arm to arm, try aligning the arms. After a bit of aligning it should work like a charm!

We hope you found this tutorial helpful. Please let us know if you don't understand something and we will help as best as we can!
Please leave a comment and give us a rating. We'd love to know what you think. And if you're in the mood click the follow button for both of us! then you'll be aware whenever we post anything. If you build this lift and post a picture, we'll put it in this step. 

Thanks for viewing! 



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    132 Discussions


    1 year ago

    I enjoyed making this lift. It's working very well. So well, that I added one module in the middle to make it taller.

    Very easy to follow instructions and lots of pictures. I had no problems building it.


    3 years ago

    it is awesome!!!!!!!!!!!i couldn't get the motor to work. A tan piece kept snapping off.


    4 years ago on Step 22

    Awesome lift... just finished and tested it... Now to try different motors on it to see if I can speed it up... its much slower than I am..


    4 years ago

    My control rods keep snapping only on the right also the orange connector by motor keeps coming off please help asap


    4 years ago

    I did it (only I did it with four lifts instead of six - parts...annoying-)
    Nice job!!

    You'r pro at guessing! Is there no "World championship guessing"? And I'm building like Austron, but only one wall.. I got not enough red rods..

    Make blue rod towers instead. :-P I always seem to have red rods left over because of making blue rod towers. And I definitely don't have enough pieces to make a ball machine go around my room.

    Yes, you'r right, but if you make high blue rod towers they are not stabilize. And don't you have enough pieces? You got more than Astron!

    I don't have more than Austron, he has 50,000+ pieces. And if I were to make a room machine I'd want it to be very dense. Blue rod towers can be as strong as red rod ones if they are the same size.

    Hmm, but you got much more than I got.. And if you make blue rod towers with the size of red rod tower I got never enough blue rods..