Petoi Bittle Manual
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3 🏗 Assemble the Frame

"The whole is more than the sum of its parts." 🔩

3.1 Start with the Unassembled Kit

You can take a glance at this assembling animation for Bittle.
Here's a more detailed hands-on tutorial on building Bittle from the kit.

3.2 Step-by-step Instruction

You can finish the following parts then put them together in later chapters.
  • Neck
  • Body
  • Upper leg
  • Lower leg
  • Head
  • Shoulder servo
  • Battery

3.2.1 Neck

  • Neck x 1
  • Servo arm x 1
  • M2x8 sharp-end self-tapping screws x 2
Put the servo arm in the neck part like the figure below. The teeth of the servo arm should face upward.
Screw two M2x8 self-tapping screws beside both sides of the servo arm. Don't over tighten the screws.

3.2.2 Body

This part is now fully assembled in our package.
  • Assembled neck x 1
  • Chasis x 1
  • Front and back plate x 2
  • Side shoulder x 2
Recognize the front and back side of the chassis. The location of the two large holes along the center track makes a difference. In our standard configuration, we define the holes to be shifted towards the tail. You can also find a small mark "A1" in the front of the chassis.
Push the back tip of the assembled neck into the slot of the chassis. Then press down the front hook until you hear a snap sound.
I designed the neck as a weak chain to disengage during a collision. Otherwise, the shock will be passed on to the servo or body frame and cause unrepairable damage.
If you want to reinforce the neck connection, you can 3D print the following part.​​​
Insert the chassis into one of the side shoulders.
Insert the front or back plate into the side shoulder. There are three tenons on each side of the plate. Insert the two front tenons as one group for better alignment.
Insert both the front and back plates.
Plug the other side shoulder to complete the body. Again pay attention to the alignment of the tenons of the front and back plates.

3.2.3 Upper leg

This part has been pre-assembled in batches after 2022.
It's a little hard to explain well with words. Please refer to the assembling instruction video at 3:23. It requires more skill than force. There's a forum post discussing installing springs with various tools.

3.2.4 Lower leg

There are five servos with long cables and five servos with short cables. The lower legs all need servos with long cables.
  • P1S servo with long cable x 4
  • Lower leg piece x4
  • M2x8 self-tapping screw x 8
Assemble the right leg. Insert the servo into the window. Watch the tutorial video to see the correct direction to fold the wire. The notch on the internal edge is designed to let the wire go through. Use two M2x8 screws to fix the servo onto the lower leg.
The left leg is opposite to the right leg. However, the front and back legs are identical. So you should make two pairs of legs with opposite configurations.

3.2.5 Head

There are five servos with long cables and five servos with short cables. The head needs a servo with a short cable.
  • P1S servo with short cable x 1
  • Chin x 1
  • Skull x 1
  • M2x8 self-tapping screw x 2
Put the servo in the chin as shown in the figure. Pay attention to the direction of the servo's wire. After that, install two M2x8 self-tapping screws.
Insert the skull into the chin so that it can rotate and bite on small gadgets. I recommend you apply some lubricant to the contact points between the skull and chin.

3.2.6 Shoulder servo

There are five servos with long cables and five servos with short cables. The upper legs all need servos with short cables.
  • P1S servo with short cable x 4
  • M2x8 self-tapping screws x 8
  • Head (assembled)
  • Body (assembled)
  • Lower leg (assembled) x 4
Put the head, body, servos, and lower legs like the figure below. Insert the short servo wires through the servo slots on the side shoulders. Pay attention to the direction of the servos carefully and place them in the correct configuration.
Side view:
Top view:
You also need to insert the wire of the head servo into the body.
Put the short wire servos into the side shoulders after confirming all the components' directions. Pay attention to the directions of the shoulder servos’ output shaft. The long wires of the lower leg servos should be inserted into the opening between the shoulder servo and the shoulder window. Use two M2x8 self-tapping screws to fix each should servo.
Please note the direction of the shoulder servo:

3.2.7 Battery

The controller board is already fixed on the body in the following picture. You can finish the Connect Wires chapter and then return here.
Insert the battery plug into the power socket under the body:
Place the battery in the direction shown in the figure below, aligning with the mounting holes:
Snap in the battery:
While holding down the battery, push it towards the head, and arrange the power cable after the battery snaps into place, as shown in the following figure:
Long-press the button on the battery for more than 3 seconds. If the red light on the battery is on, please charge it until the green light on the battery turns solid before using it. The power supply starts to supply power, and the yellow and blue LEDs on the NyBoard light up at the same time.