Back Leg

3. Back Leg Assembly¶

In this step, we will assemble the back legs of the Robot Dog and mount them on the second ice cream stick servo motor horn assembly prepared earlier.

The back leg assembly works together with the front leg assembly to create the walking motion of the Robot Dog.

Back Leg Assembly Parts

Parts Required¶

Part	Quantity	Description
Back legs	2	Cardboard back leg pieces
Screws	4	Used to fix the legs to the ice cream stick / horn assembly
Nuts	4	Used to lock the screws in place
Servo motor horn assembly	1	Second servo motor horn assembly prepared using servo motor, horn, and ice cream stick

Assembly Instructions¶

1. Identify the Back Legs¶

Take the two cardboard back leg pieces.

The back legs are similar to the front legs but will be mounted on the second servo motor assembly.

Keep both back legs in the same direction before mounting.

2. Place the Second Servo Horn Assembly¶

Take the second servo motor horn assembly.

Place it on the table with the ice cream stick facing horizontally.

This ice cream stick will act as the support bar for mounting both back legs.

3. Align the Back Legs¶

Place one back leg on the left side of the ice cream stick and the other back leg on the right side.

Make sure:

Both legs are facing the same direction.
The rounded ends are pointing downward.
Both legs are parallel to each other.
The marking lines on the two legs are aligned.
The legs are mounted at the same height.

4. Insert the Screws¶

Insert the screws through the holes in the back legs and ice cream stick.

Use two screws for each.

Do not fully tighten the screws immediately. First align both legs correctly.

5. Tighten the Nuts¶

Once both back legs are aligned, tighten the nuts gently.

The legs should be held firmly, but they should not be crushed or bent.

Avoid overtightening because it may damage the cardboard or restrict the movement.

6. Check the following¶

Both back legs move together.
The legs do not touch the servo body.
The ice cream stick does not bend too much.
The screws and nuts do not block movement.
The servo horn remains firmly attached to the servo shaft.

Back Leg Assembly Video¶

Important Notes¶

Do not force the servo horn while checking movement.
Make sure the back legs are not mounted upside down.
Keep both legs at the same level.
Do not overtighten the nuts.
Keep the servo wire free so that it does not get pulled while walking.

Troubleshooting¶

Issue	Possible Reason	Solution
Back legs are loose	Nuts are not tightened properly	Tighten the nuts gently
Legs are not aligned	Legs moved while tightening	Loosen, realign, and tighten again
Servo horn is not moving freely	Screws are too tight or touching the servo	Adjust the screw position and loosen slightly
One leg is higher than the other	Uneven mounting	Remove and mount both legs at the same height
Ice cream stick bends	Legs are misaligned or screws are too tight	Realign the legs and tighten evenly
Servo wire gets pulled	Wire is trapped or twisted	Free the servo wire before mounting to the body

Completed Step¶

The back leg mechanism is now ready.

In the next step, we will check both the front leg assembly and back leg assembly together before fixing them to the Robot Dog body.