Introduction: Dual Axis Arm Lift

A new lift for knex ball machines - like a normal arm lift, but with 2 axes of movement! While similar to the lift found here (by Thibault Art), the initial version of this lift has been collecting dust for around 3 years now... so consider it more of a happy coincidence rather than direct inspiration.

Either way, it was long overdue to finally share this lift. It works very reliably, and comes prepared to handle any amount of balls you throw at it, thanks to a timing wheel located on the entrance path. The only real challenge in constructing this lift is calibrating the arms to be in just the right position - something which will be explained in detail at the end of the instructions.

While a full piece count won't be provided (unless a kind soul who builds this lift decides to make one), below is a list of the most specialized/specific pieces that you'll want to make sure you have before starting:

- 1 Blue Motor

- 3 Big Yellow Gears

- 1 Yellow Gear

- 4 Red Gears

- 4 Small Blue Gears

- 1 Black Rod

- 2 Tan Rods

Of course, you can use a different color motor, however each color has a different speed and may affect how well the lift works. Likewise, the black and tan rods can be swapped out for gray and red rods respectively, but will result in a less stable and ultimately less reliable lift.

While building this lift, be sure to read the notes for each image, as some small mistakes were made in the pictures, and some clarifications will help clear up the more confusing parts.

With that, onto the first step!

Step 1: Making the Gearbox

1) Note the orientation of the back blue connector. The following images will have it flipped (purple connector on white rod) but this picture has it correct.

8) The rightmost white rod should not actually be there

11) Same with this white rod

14) Rightmost 3D connectors should be two blues, not a purple and a blue. Also, note that the yellow connector in the middle is gone, to go on the black rod in the next picture.

Step 2: Making the Gearbox Supports

1) If you're building this on a hard surface, consider making the base flat instead. Here I have the 3D connectors sticking down below the bottom-most rods, which works better for carpeted floors.

13) Add this yellow rod

14) In case you didn't catch the previous note, this 3D connector should be oriented this way.

15) Similarly, this 3D connector should be 2 blues, not a blue and a purple.

Step 3: Making the Ball Distributor

12) Make two of these

15) You have to sort of force this orange connector to wedge in there, but it won't fully snap onto the white rod.

18) Make sure the wheel is oriented the same way as in this picture

19) Same as 18

Step 4: Making the Arms

16) It will be easiest to set up if you have one of the arms on the same side as the motor, as shown here. Also notice the blue clip behind the gear

18) Repeat steps 9-17 for the other side. Set second arm facing upwards, as shown here.

Step 5: Build the Entrance Path

Step 6: Build the Exit Path

Step 7: Calibrate the Arms

Oh boy, this one is a doozy. What you want to do is first line up the spoke of the vertical (black in the picture) gear with the spoke of the horizontal (yellow in the picture) gear. You should be able to pretty easily lift up the gear to rotate the arm into place without having to take anything apart. These two spokes won't line up perfectly, so you'll want to line up the black spoke just slightly to the left of the yellow spoke. This is shown in pictures 1 and 2. From here, you'll want to rotate the arm 9 notches (or teeth), clockwise. This should position the arm just so that it barely clears the green connectors on the entrance path (picture 3), but also picks up a ball properly. Thankfully, it is easy to know if you have the positioning wrong:

You moved too many notches if the arm catches on the entrance track.

You moved too few notches if the arm does not pick up the ball.

In both lifts I made (one for the video, and another for the instructions), it held true that only a single notch worked, which again, is 9 notches clockwise from lining up the black spoke to the left of the yellow spoke. It is possible however that your lift might be different, so if my positioning doesn't work for you, fiddle around with it (could also modify the entrance track).

Of course, once you have properly aligned the first arm, turn the motor on to switch the position of the two arms, and repeat the process for the second arm.

Step 8: Done!

Please let me know if there are any steps that could be made more clear, mistakes in the instructions, or just general questions. If you ended up making the lift, post a video or picture, I'd love to see it in action!

Enjoy your new Dual Axis Arm Lift!