Parts (one leg)
- (x1) Servo（SG90 or MS18）
- (x1) Servo horn on each wing
- (x1) Servo horn on one wing
- Leg_Bracket_A (upper left) (SG90 or MS18)
- Leg_Bracket_B (upper right) (SG90 or MS18)
- Leg_Base (center)
- Joint_Servo_A (center left) ((SG90 or MS18). Common parts with arms)
- Joint_Servo_B (center right) (arms and common parts)
- Leg_Foot (bottom. Only this part is different on the right and left. The photo is for the left foot)
Micro:bit setup code “microbit-ForSetUp.hex”
This code is also published on thingiverse.
Servo horn and bracket preparation
Drilling
This step is not necessary if you can print out with a clean hole.
If the holes in the red circles below are incomplete, clean them with a 2mm pin vise.
Servo horn installation 1
Use the horns on both wings that come with the servo. (right)
Cut, leaving 3 holes. (left)
Attach the above horn to Leg_Base. Secure with M1.4 tapping screws. Drilling a pilot hole with a 1 mm drill will make it easier for screws to enter.
Secure the two places with M1.4 tapping screws.
Servo horn installation 2
Attach the one-winged horn that came with the servo to Joint_Servo_A.
As with Installation 1, make a pilot hole with a 1 mm drill first to make it easier for screws to enter.
Fasten with M1.4 tapping screws.
Servo Bracket
Insert an M2 nut or M2 locknut in the left part (Joint_Servo_B).
Pass the M2x8mm countersunk screw through the right part (Leg_Blacket_B) from behind and cover it with a washer. (The photo is for MS18)
Align the two parts and tighten from behind. * There is a washer between the parts.
Tighten it once and loosen it slightly enough to move the two parts.
The photo is for M2 locknut.
If it is not a locknut, you can cover it with an M2 nut to make it a double nut. It will not come off easily.
Attach Leg_Bracket_A to the servo.
If it is unstable, fix it with the screw attached to the servo.
Install the parts assembled above (Leg_Blacket_B and Joint_Servo_B).
Installation of servo and servo horn
Import setup code
Import the setup code “microbit-ForSetUp.hex” into the Micro:bit.
Servo and Servo Horn 1
Attach the foot servo connector to the body.
In the case of the right foot, it will be number 6, so connect it to SV6. Back side is the brown (GND).
In the case of the left foot, it will be number 5, so connect it to SV5.
Install the Micro:bit and turn it on.
With the switch on, align the servo with each part.
As shown in the photo, it may be slightly off, but install it so that it is as straight as possible. Small deviations can be adjusted after assembly.
Screw the servo horn with the screws attached to the servo.
Servo and Servo Horn ２
As with the foot servo horn, keep the Micro:bit powered on and align the body with the Leg_Base.
The body and Leg_Base should also be as straight (vertical) as possible. Notice the shape of the square red frame. The red frame is on the battery side.
Secure with the screws attached to the servo.
Fixing the foot
Ankle attachment
Attach the foot.
If it is unstable, use M1.4 tapping screws.
If you make a pilot hole with a 1 mm drill, it will be easier for screws to enter.
Body and foot attachment
Align the upper foot with Foot_Base as shown in the picture.
If it is unstable, make a pilot hole with a 1 mm pin vise and fix it with a 1.4 mm tapping screw.
Connection of both feet and connector
Similarly, create the other leg and attach it to the Body.
The cord goes through the holes in Leg_Base and Body_Base and connects to SV5 and SV6.
The servo number for the left foot is 5, and the servo number for the right foot is 6.
This completes the foot assembly.