Introduction: K'nex Semi-Circle Lift

Picture of K'nex Semi-Circle Lift

Hey peeps! Tornado96 here to bring you an instructable of the Semi-Circle lift from my ball machine, Dragon Gem. This is a very simple lift but useful if you want to see something a bit more exciting than a chain lift and don't have an incredible amount of pieces. It is made with a perfectly circular "guide" that forces the chain to rise in a swift half-moon motion. Please enjoy and don't forget to comment and subscribe to see more k'nex models from me!

Now let's get on to the piece count!

Step 1: Piece Count

Picture of Piece Count

I hope you like maths because now you have to count the pieces you have to make sure you have enough for this build! If I have any miscalculations please let me know!


Green: 78
White: 54
Blue: 58
Yellow: 46
Red: 62
Grey: 35   


Light grey 1-slot: 26
Grey 2-slot: 18
Orange 2-slot: 50
Red 3-slot: 26
Green 4-slot: 4
Yellow 5-slot: 68
Purple 3D 4-slot: 71
Blue 3D 7-slot: 19
White 8-slot: 6


Black Y-clips: 8
Flexi-rods: 2
Blue spacers: 9
Grey spacers: 14
Red gears: 6
Motor: 1
Chain links: 91

Total: 752

Now that you have counted the pieces it's time to move on to the building!

Step 2: Entrance Track

Picture of Entrance Track

This structure supports the track where the ball enters the lift. Don't forget to follow image notes where they are needed!

1. part 1 of main frame
2. part 2 of main frame
3. entrance track
4. connecting part 2 and 3
5. connecting part 1 to part 4
6-7. part 3 of main frame
8. connecting it all together
9-10. the rest of the entrance track
11. connecting it to the main base
12. what you should have so far
13. holding track
14-16. connecting the holding track
17. gears
18. connect it the the rest
19-20. more holding track.
21. connect it ( do not connect teh yellow rods. They will be connected later on)
22. Overview of step 1

Step 3: Lower Backbone Supports

Picture of Lower Backbone Supports

Now you get to start shaping the lift with the Semi-circle backbone. A lot of Backbone-Support connections were necessary to prevent the backbone from moving sideways which would affect the chain on it's way up.

1. lower frame part 1
2. beginning of the backbone
3. more backbone
4. connecting 2 and 3
5. connecting backbone to lower frame
6. another angle
7. lower frame part 2
8. connecting part 7 to 1-6
9. another view
10. middle frame part 1
11. middle frame part 2
12. connecting 9 and 10
13-14. connecting the middle frame to the lower frame
15-17. connecting step 3 to step 2 

Step 4: Middle Tower and Backbone

Picture of Middle Tower and Backbone

Just as the title of the step suggests you will now build the middle section of the tower and the freestanding section of the backbone.

1. backbone
2. connect it to steps 2-3
3. middle tower
4. connecting the tower

Step 5: Motor Hub and Exit Track

Picture of Motor Hub and Exit Track

Next you will build the motor hub and the exit track. The gearing tucks in nicely with the exit track!

1. lower motor hub support
2. tension gear
3. connecting them together
4. Motor axle
5. exit track part 1
6. another view
7. exit track part 2
8. another view
9. connecting the exit track together
10. adding the motor axle
11. exit track support
12. adding exit track support to motor hub
13. another view
14. connecting the motor hub to the lower support
15. another view

Step 6: Finishing the Semi-circle

Picture of Finishing the Semi-circle

Now you'll build the last part of the backbone that connects to the motor hub and exit track.

1. side support part 1
2. backbone
3. connecting backbone to side support
4. another view
5. side support part 2
6. putting it all together
7. attaching step 6 to step 5
8. another view
9. connecting it all to the tower
10. coming along nicely! :-)

Step 7: Adding the Chain

Picture of Adding the Chain

Without chain, the balls won't get very far. Let's add some, shall we?

1. section 1. build 9 of these
2. section 2. Build 1 of these
3. all the sections you should have. 10 in total
4. Connect it all together!
5. close up of positioning of the chain on the upper gears
6. another view
7. close up of positioning of the chain on the tension gears
8. close up of positioning of the chain on the lower gears

Step 8: You're Done!

Picture of You're Done!

Congratulations! You have just achieved a great feat worthy of the most noble k'nex builders! May this contraption aid you in your quest as you build your own ball machines! 

heaps corny, I know but it sounds cool! :-D

Now go try it out and let me know how it goes! Always great to receive feedback!

Thanks for building!
Comment, rate and subscribe for more!

See you guys next time! It's been a pleasure teaching you!


origamiwithnathan (author)2017-09-05

thanks so much for creating these instructions, works great, now all I have to do is build the tracks!

bennett2198 made it! (author)2017-08-20

Great design! The semi-circle part really adds to the look of the lift.

The instructions were very clear and easy to follow.

Here is the video of it working.

I modified the Ball Pickup Arms. The first picture shows the original on the left and the changes I made on the right and front. I added a "Y" clip as shown to move it away from the chain. This made the chain run a little smoother as it is completely straight. Then I had to removed one chain link and modified the back guide to tighten it up as it was still too loose.

The other two pictures show the changes to stop the pickup arms from catching on the ramp as they are a little longer than before.

Again, thanks for the instructions.


Linkin_J_Knex made it! (author)2016-02-28

Here it is

Linkin_J_Knex (author)2016-02-27

I built this beautiful and bigger than I expected lift :) I'll send you a picture tomorrow if I remember :)

Gargamel-Knex (author)2013-08-04

Beautiful lift, I am now working for a ball machine ....

Leigo Andre (author)2012-07-27

Totally of the counting! :D

Tornado96 (author)Leigo Andre2013-02-15

Sorry? I'm not sure what you mean by that haha

Leigo Andre (author)Tornado962013-08-02

Actualy, seeing this comment 1 year later me neither!:D EPIC

cooljupjup (author)2013-02-14

it works with the black/white balls?

Tornado96 (author)cooljupjup2013-02-15

I'm pretty sure it does. If it doesn't it would be easily modifiable

cooljupjup (author)Tornado962013-02-16

yessss it wil work but you gonna modify something on the rail in the bottom

Tornado96 (author)cooljupjup2013-02-16

Yes, that was my expectation. Great to see you got it to work! :)

cooljupjup (author)Tornado962013-02-16


cooljupjup (author)Tornado962013-02-16


albydesign (author)2012-08-24

Awesome!! 5* :-)

Tornado96 (author)albydesign2013-02-15

Thanks man! :D

KNEX GUNS ROCK (author)2012-07-02

thx it works awesome:D

Tornado96 (author)KNEX GUNS ROCK2012-07-07

awesome! :)

KNEX GUNS ROCK (author)Tornado962012-07-26

yes awesome:D

sandroknexmaster (author)2012-06-02

I've built it and it works very good! I'm gonna use this one in my next ball machine!

poncho531 (author)2012-05-09

How tall is this lift?

Tornado96 (author)poncho5312012-05-10

5 red rods. Just count :P

jameshond (author)2012-04-26

nice lift i make this lift it is nice

Tornado96 (author)jameshond2012-04-27

thanks man! glad it worked!

Purple Waffles (author)2012-04-23

Yay! More stuff from Tornado! Speaking of which, I owe you pictures of my new ball machine in exchange for the Dragon Gem photos...

Tornado96 (author)Purple Waffles2012-04-23

You don't owe me. You won the contest... :-P

Purple Waffles (author)Tornado962012-04-24

Oh yeah... i have bad memory X-D

I could still send you pictures anyway...

Shadowman39 (author)2012-04-23

That's a very nice lift you have there...

But seriously, cool lift. :-P I laughed at the part that says the balls wouldn't get very far without chain, and also the ending. But shouldn't the backbone be called the semi-circle? Otherwise I'm going to call it the backbone lift just to annoy you. :-)

Tornado96 (author)Shadowman392012-04-23

backbone sounds cooler. Nuff said


Shadowman39 (author)Tornado962012-04-23

Is there going to be a video?

Tornado96 (author)Shadowman392012-04-23

Not for this one. But any lifts after this one will

Shadowman39 (author)Tornado962012-04-23

So what lifts are left to post now?

Tornado96 (author)Shadowman392012-04-23

well for now just the reverse arm lift. The double conveyor belt lift doesn't really count. It's too simple. Of course, the new lifts in my new ball machine! B)

Shadowman39 (author)Tornado962012-04-23

There's new lifts in that? :-P

Tornado96 (author)Shadowman392012-04-23

Yup! You'll just have to wait and see ;-)

Shadowman39 (author)Tornado962012-04-24

Cool :-)

Sorunome (author)2012-04-23

Finally there are instructions on this one...even thought i like it with reds more :P

Tornado96 (author)Sorunome2012-04-23

The red does look good in contrast with the yellow connectors but it's too big for my liking... If there were red rods the size of yellow rods I would be very happy!

Sorunome (author)Tornado962012-04-24

haha, spray your yellow rods red :P

Sorunome (author)Sorunome2012-04-23

btw, rated it 5*s ;)

KneXtreme (author)2012-04-23

Nice lift. I'm going to use it. 5*s

Purple Waffles (author)KneXtreme2012-04-23


Tornado96 (author)KneXtreme2012-04-23

have fun!

knexpert#10829476 (author)2012-04-23


thanks man!

About This Instructable




Bio: 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 ... More »
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