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4. Project: Clock > Assembly Instructions

Assembly Instructions

Once you have gathered together the parts, it’s time to build! The following instructions show you how to build the clock. While you put it together, feel free to experiment and alter the design—the worst that could happen is that the clock just won’t work! If that happens, just back up to the previous step and start over again.

The completed clock model—just add electronics
Figure 4-4. The completed clock model—just add electronics

Prepare the Gear

The only tricky part of the Lego build is that you’ll have to modify the central 40-tooth gear in order for the clock to work. The reason is that in order for the hour and minute hands to both rotate freely without fear of collision, the gear upon which the hour hand is attached must rotate freely around the axle that turns the minute hand. Unfortunately, Lego doesn’t make a gear with a smooth central hub. Their gears all feature cross-axle hubs, which makes sense—you usually want your gear to derive its energy from a cross axle, or impart energy to one.

Since Lego has not seen fit to create such a gear, we did. We took a 40-tooth gear and filled in the holes around the axis with hot glue, in order to strengthen the hub for drilling. Then, using a 3/16th-inch bit and power drill, we drilled out the hub so it rotates freely around a standard cross axle.

We modified the 40-tooth Technic gear to have a smooth hub; We filled in the surrounding holes with hot glue to ensure the drilling doesn’t weaken the gear
Figure 4-5. We modified the 40-tooth Technic gear to have a smooth hub; We filled in the surrounding holes with hot glue to ensure the drilling doesn’t weaken the gear

Build the Lego Model

Next, we’ll assemble the clock itself. This is your opportunity to experiment with the model’s design and customize it to your own liking.

  1. Begin with a couple of 3x7 double angle beams as shown in Figure 4-6.

  2. Add two 15M beams and one 11M beam (see Figure 4-7).

    Step 1: Setting up the angle beams
    Figure 4-6. Step 1: Setting up the angle beams
    Step 2: Adding some more beams
    Figure 4-7. Step 2: Adding some more beams
  3. Now work on the other side with two more 3x7 double angle beams, as shown in Figure 4-8.

  4. You’ll need supports as well; add one 3M and one 11M beam. Figure 4-9 shows how they go together.

    Step 3: Making the other side with angle beams
    Figure 4-8. Step 3: Making the other side with angle beams
    Step 4: Adding two supports
    Figure 4-9. Step 4: Adding two supports
  5. Combine the two assemblies (Figure 4-10) and set them aside for now.

  6. Next, connect two pins to an 11M beam as shown in Figure 4-11.

    Step 5: Combining the two assemblies
    Figure 4-10. Step 5: Combining the two assemblies
    Step 6: Connecting the pins to the beam
    Figure 4-11. Step 6: Connecting the pins to the beam
  7. Next, connect an 11M beam (see Figure 4-12).

  8. Take what you have so far (Figure 4-13) and build another one just like it!

    Step 7: Adding the beam from the previous step
    Figure 4-12. Step 7: Adding the beam from the previous step
    Step 8: Make one just like this
    Figure 4-13. Step 8: Make one just like this
  9. Add four 10M cross axles and bushes to one of the assemblies you built as shown in Figure 4-14, but leave the other one alone for now.

  10. Add half bushes to the back to keep the cross axles in place as shown in Figure 4-15. (By the way, don’t use the yellow half-bushes we specified; you’ll need them for the clock’s hands.)

    Step 9: Adding 10M cross axles and bushes
    Figure 4-14. Step 9: Adding 10M cross axles and bushes
    Step 10: Adding half bushes
    Figure 4-15. Step 10: Adding half bushes
  11. Add four pipes and four more half bushes. Figure 4-16 shows how it goes together.

  12. Add some 9M cross axles and bushes (Figure 4-17).

    Step 11: Adding pipes and half bushes
    Figure 4-16. Step 11: Adding pipes and half bushes
    Step 12: Adding more cross axles and bushes
    Figure 4-17. Step 12: Adding more cross axles and bushes
  13. Now let’s work on the motors. Add three 3M connector pegs as shown in Figure 4-18.

  14. Connect a 7M Technic beam (see Figure 4-19).

    Step 13: Add connector pegs to the motors
    Figure 4-18. Step 13: Add connector pegs to the motors
    Step 14: Connecting the beam
    Figure 4-19. Step 14: Connecting the beam
  15. Grab the second motor, and add three 3M pegs as shown in Figure 4-20.

  16. Connect the two motors together with the help of the Technic beam (see Figure 4-21).

    Step 15: Adding pegs to the other motor
    Figure 4-20. Step 15: Adding pegs to the other motor
    Step 16: Connecting the two motors
    Figure 4-21. Step 16: Connecting the two motors
  17. Throw another 7M beam on there (Figure 4-22).

  18. Add the motors to the structure you built earlier, as shown in Figure 4-23.

    Step 17: Adding another beam
    Figure 4-22. Step 17: Adding another beam
    Step 18: Combining the motors and the assembly
    Figure 4-23. Step 18: Combining the motors and the assembly
  19. Throw the duplicate assembly onto the back (see Figure 4-24).

  20. Add six bushes as shown in Figure 4-25.

    Step 19: Attaching the duplicate assembly
    Figure 4-24. Step 19: Attaching the duplicate assembly
    Step 20: Adding bushes
    Figure 4-25. Step 20: Adding bushes
  21. Add angle beams for legs. Figure 4-26 shows this.

  22. Insert two 7M cross axles as shown in Figure 4-27.

    Step 21: Adding the legs
    Figure 4-26. Step 21: Adding the legs
    Step 22: Inserting the cross axles
    Figure 4-27. Step 22: Inserting the cross axles
  23. Two more angle beams complete the legs (Figure 4-28).

  24. Let’s work on gears. Add a 24-tooth gear to the end of a 12M cross axle (see Figure 4-29).

    Step 23: Adding more angle beams
    Figure 4-28. Step 23: Adding more angle beams
    Step 24: Connecting the 24-tooth gear to a cross axle
    Figure 4-29. Step 24: Connecting the 24-tooth gear to a cross axle
  25. Thread the cross axle through the center hole, between the motors’ orange hubs. Figure 4-30 shows where to put it.

  26. Build another gear and axle assembly, this one with a couple of bushes, as shown in Figure 4-31.

    Step 25: Threading the cross axle
    Figure 4-30. Step 25: Threading the cross axle
    Step 26: Building another gear and axle assembly
    Figure 4-31. Step 26: Building another gear and axle assembly
  27. Insert the cross axle through the topmost visible hole in the vertical support (Figure 4-32).

  28. Secure the axles with two bushes each as shown in Figure 4-33.

    Step 27: Inserting the cross axle through the top
    Figure 4-32. Step 27: Inserting the cross axle through the top
    Step 28: Securing the axles
    Figure 4-33. Step 28: Securing the axles
  29. Add two bushes and an 8-tooth gear to a 6M cross axle. Figure 4-34 shows how they go together.

  30. Connect the assembly from Step 29 to the upper motor’s hub so that the top two gears mesh (Figure 4-35).

    Step 29: Adding the bushes and 8-tooth gear to a cross axle
    Figure 4-34. Step 29: Adding the bushes and 8-tooth gear to a cross axle
    Step 30: Connect to the upper motor’s hub
    Figure 4-35. Step 30: Connect to the upper motor’s hub
  31. Add a bush and an 8-tooth gear to a 4M cross axle as shown in Figure 4-36.

  32. Connect the cross axle to the lower motor’s hub, and make sure the lower two gears mesh. Figure 4-37 shows how it all connects.

    Step 31: Adding a bush and 8-tooth gear to a cross axle
    Figure 4-36. Step 31: Adding a bush and 8-tooth gear to a cross axle
    Step 32: Connecting the cross axle to the lower motor’s hub
    Figure 4-37. Step 32: Connecting the cross axle to the lower motor’s hub
  33. Add a 24-tooth gear and half-bush (Figure 4-38).

  34. Add the drilled out 40-tooth gear. Make sure it rotates freely, then mesh it with the top gear as shown in Figure 4-39.

    Step 33: Adding a 24-tooth gear and half-bush
    Figure 4-38. Step 33: Adding a 24-tooth gear and half-bush
    Step 34: Adding the 40-tooth gear
    Figure 4-39. Step 34: Adding the 40-tooth gear
  35. Add the angle element and two pegs (Figure 4-40).

  36. Connect a 9M beam to the 40-tooth gear (see Figure 4-41). This is your hour hand.

    Step 35: Adding the angle element and pegs
    Figure 4-40. Step 35: Adding the angle element and pegs
    Step 36: Building the hand
    Figure 4-41. Step 36: Building the hand
  37. Build the minute hand out of a cross axle with end stop, three pipes, and two half bushes. Figure 4-42 shows the assembly.

  38. Add the minute hand to the angle element as shown in Figure 4-43.

    Step 37: Building the minute hand
    Figure 4-42. Step 37: Building the minute hand
    Step 38: Attaching the minute hand
    Figure 4-43. Step 38: Attaching the minute hand
  39. Next, let’s work on the button assembly. Add two double cross blocks to a pair of 6M cross axles (Figure 4-44).

  40. Add two touch sensors to the cross axles as seen in Figure 4-45.

    Step 39: Adding cross blocks
    Figure 4-44. Step 39: Adding cross blocks
    Step 40: Attaching touch sensors
    Figure 4-45. Step 40: Attaching touch sensors
  41. Secure the ends of the cross axles with bushes (see Figure 4-46).

  42. Add a couple of connector pegs (Figure 4-47).

    Step 41: Adding bushes
    Figure 4-46. Step 41: Adding bushes
    Step 42: Attaching two pegs
    Figure 4-47. Step 42: Attaching two pegs
  43. Add a couple of connector pegs to attach the buttons (Figure 4-48).

Step 43: Add the button assembly
Figure 4-48. Step 43: Add the button assembly

Install the Arduino

As with the Drawbot in Chapter 1, you’ll need to use Bricktronics mounting plates to attach your Arduino to the clock, as shown in Figure 4-49. Use the exposed cross connectors and cross axle ends on the back of the clock and thread them through the Technic holes in the plates, just like you did in Chapter 1. Attach wires per Figure 4-50. Power the clock with an Arduino-compatible wall wart (9-12V, 2.1mm center positive barrel connector, 1.3A or more) to run the clock. All you have to do is program the clock and you’re done!

Use your Bricktronics mounting plates to add the Arduino
Figure 4-49. Use your Bricktronics mounting plates to add the Arduino
Attach the Mindstorms wires as you see here
Figure 4-50. Attach the Mindstorms wires as you see here
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