Introduction: Lum: Yoyo String Rig

The lüm emerged from the idea that every yoyoer should have the ability to easily make their own, precisely wound string, and they should be able to do so with very low barriers to entry. What we've designed is more than a yoyo string twisting machine. This machine is capable of making strings out of any material, at nearly any length, with any thickness, and most importantly capable of winding your string the same amount every time.

The lüm is run by an Arduino microcontroller which controls its onboard motor using an encoder. These may sound like big words, but all it means is that the lüm knows exactly how many times it's motor has spun and it will twist your strings the same time, every time. This makes the lüm the most consistent home rig available.

In addition to its unprecedented consistency, the lüm has been designed to pack small and can easily be stored in the corner of a room and then brought to life any time you need a new string.

We could have charged for this design, but we wanted to bring it to the yoyo community for free. If you want to make yoyo strings, you can now.

Step 1: Bill of Materials and Engineering Drawings

First you're going to want to buy everything that's in the attatched bill of materials. We've already done the work to get the best quality parts and our design is build to their specifications. If you buy substitutes then we can't guarantee that your lüm will work properly and you won't be saving much money.

The attached drawings will give you all the dimensions that you need to build this project.

Step 2: Cut Your Wood

Reference the PDFs attached to this step to get the necessary lengths of all your 2X4s and dowels. Put these PDFs somewhere safe for the next steps.

You should have:

  • 2
    • 10' 2X4s
  • 2
    • 2.87" 2X4s
  • 1
    • 30.34" 2X4
  • 6
    • 10" long 1" dia dowels

Step 3: Create Rod Holder Assembly

Layout your rod holder in pencil. All critical dimensions are in the Rod Holder drawing attached in step one (in fact all the important dimensions of this project are in one of the drawings attached in step one, really take some time to study them!). Once you've laid out where the holes go, then drill them out and put a screw in each of the holes in preparation for attaching the dowels and the standoffs.

Safely drill a hole in each dowel. Do as I say, not as I do. You should use some kind of workholding when doing this step to ensure that you don't drill through your hand. This is a starter hole, so the diameter isn't critical, ours is around .16" diameter.

Now bring it all together by attaching the rods to the 2X4 with the screws you set up earlier. Finnally screw the standoffs into place and you've got yourself a rod holder.

Step 4: Attach All Hardware to Machine Arms

Reference the drawings from step one for where each piece of hardware should go. You can then use the hardware itself as a stencil to get an idea of where to put each hole. The other option is to use a ruler and the dimensions from the drawing, but I'll leave that choice up to you.

Step 5: Electronics Box: Step 1

Get the DC power jack

Step 6: Electronics Box: Step 2

Get a red and black 22 gauge wire cut at approximately 5 inches long

Step 7: Electronics Box: Step 3

Solder the wires onto the jack, ensuring the red wire is on the positive lead and black is on the negative lead

Step 8: Electronics Box: Step 4

Get 3D printed box and drill out all the holes for the screws

Step 9: Electronics Box: Step 5

Place leads of the DC power jack into the motor shield, and secure them with the screws

Step 10: Electronics Box: Step 6

Get the DC motor with encoder

Step 11: Electronics Box: Step 7

Stick lead wires into motor plug, ensuring to match the colors

Step 12: Electronics Box: Step 8

Stick motor leads into motor shield and secure with screws

Step 13: Electronics Box: Step 9

Get keypad and connector pins

Step 14: Electronics Box: Step 10

Solder the connector pins to the keypad

Step 15: Electronics Box: Step 11

Get 8 pin ribbon wires

Step 16: Electronics Box: Step 12

Connect the wires to the keypad

Step 17: Electronics Box: Step 13

Upload code to Arduino microcontroller from this Github link:

Step 18: Electronics Box: Step 14

Install Arduino into electronics box

Step 19: Electronics Box: Step 15

Install keypad into electronics box

Step 20: Electronics Box: Step 16

Plug in leads to Arduino pins 39, 41, 43, 45, 47, 49, 51 and 53, making sure to plug the right pins from the keypad into the Arduino pins. Reference Step 12 to help you with this.

Step 21: Electronics Box: Step 17

Get the LCD screen and a 4 pin ribbon wire

Step 22: Electronics Box: Step 18

Connect the wires to the LCD screen pins

Step 23: Electronics Box: Step 19

Install the LCD screen into the electronics box

Step 24: Electronics Box: Step 20

Get the DC motor shield previously created

Step 25: Electronics Box: Step 21

Install the DC motor to the electronics box

Step 26: Electronics Box: Step 22

Install the DC motor shield, make sure you match the pins exactly with the Arduino

Step 27: Electronics Box: Step 23

Install the power jack into the designated hole in the electronics box

Step 28: Electronics Box: Step 24

Place the pins for the encoder and DC motor controls into the designated pins on the motor shield.

Yellow: Pin 4

White: Pin 5

Blue: +5V

Green: Ground

Step 29: Electronics Box: Step 25

Cable management

Step 30: Electronics Box: Step 26

Plug the screen into the Arduino, ensuring the correct wires are placed into the right pins. Reference Step 18 to help with this

Gnd: Gnd

Vcc: +5V (another plug found in the left side pins



Step 31: Electronics Box: Step 27

Plug the electronics box in with the 12V Power supply, make sure the 12V power supply has a max current supply of 2a. If all is installed correctly the Arduino should turn on and display this screen.

Step 32: Electronics Box: Step 28

Pressing A will turn the motor on and the screen will display the TPI you've chosen. The motor will automatically stop at the designated TPI.

Step 33: Electronics Box: Step 29

Install the hook in whatever fashion you can. We used a brass connector and glued the hook in place, but you can use anything to get the hook to stay in place.

Step 34: Electronics Box: Step 30

Your electronics box is complete and ready to install on the machine!

Step 35: Bring It Alllll Together

Based on the assembly drawings, start to attatch all the subassemblies together. If you've already got the holes in place then it should be as simple as lining part up and screwing then into place.