Pre-Lab Exercise · Build Your Demobot
KIPR · Botball Explorer
Build Phases

Pre-Lab · Build Guide

Build Your Demobot

Complete this before Lab 1 of any path. Every C lab, Python lab, and Discovery project runs on the robot you are about to build.

Time Needed
60–90 minutes
Work In
Pairs or small teams
You Need
Wombat kit · screwdriver · charged battery
Finish Line
Servo Demobot with arm and claw

Work through the steps below at your own pace. Read each instruction fully, look at the pictures, and check your work against the finish photos before moving on.

Phase 0 — Before You Build

Do this first

Find your battery and battery charger and plug the battery in to charge now, while you complete the rest of the build. A dead battery at the end means waiting instead of driving.

Video coming soon.

Your kit is organized into labeled bags. The instructions will always tell you which bag a part comes from — for example (Screw Bag A) or (LEGO Bag). Keep the bags closed until a step asks for something inside.

Labeled kit bag 1.
Labeled kit bag 2.
Labeled kit bag 3.
Labeled kit bag 4.
Labeled kit bag 5.
Labeled kit bag 6.
Labeled kit bag 7.
Labeled kit bag 8.

Phase 1 — Know Your Parts

These are the small parts you will use over and over. Learn their names now — every build step names its parts exactly.

Parts video coming soon.

Advised parts

This is everything required by the full build. Quantities for bolts and nuts are generous so that when you drop pieces, you can grab a spare and keep moving.

Pins & Standoffs

Nuts, Bolts, and Motor/Servo Hardware

Lego & Servo Pieces

LEGO Pins

Heads up

The color of a LEGO piece in your kit may be different from the pictures in this guide. Match the shape and size, not the color.

Axle pin, 1 required
LEGO pin, 6 required
Long 1.5 LEGO pin, 1 required
Short, three-quarter LEGO pin, 2 required
H pin with four posts, 1 required

Standoffs

Half-inch standoff, 2 required
One-inch standoff, 1 required
Two-inch standoff, 1 required
Three-inch standoff, 1 required

Nuts & Bolts

Spike nut, at least 12 required
Short quarter-inch bolt, 12 required
Medium half-inch bolt, 12 required
Long three-quarter-inch bolt, 12 required

Motor & Servo Hardware

These screws are in the motor and servo bags, not the screw bags. There are no extras, so be careful not to lose these.

Small silver servo screws and washers. 3 pictured, 2 required
Small black motor bolt

Phase 2 — Build the Basic Demobot

The Basic Demobot is the driving base: chassis, two motors, two wheels, a caster, and the Wombat controller. Follow the steps in order and check every picture.

1. Attach the 1×9 Liftarm

Video coming soon.

  1. Line up a 1×9 LEGO Liftarm (LEGO Bag) on the short end of the chassis as shown.
  2. Attach the piece to the chassis with two medium bolts (Screw Bag A) and two nuts (Screw Bag C).
  3. Add two black LEGO pins (LEGO Bag) to the end of the 1×9 Liftarm as shown.

Chassis found in the Botball Metal Pieces Box.

1 · Line up on the short side
2 · Bolt it down
3 · Add two pins

2. Attach the 1×11 Liftarm

Video coming soon.

  1. Line up a 1×11 LEGO Liftarm (LEGO Bag) on the short end of the chassis as shown.
  2. Attach the piece to the chassis with two long bolts (Screw Bag B) and two nuts (Screw Bag C).
1 · Line it up
2 · Bolt it down

3. Mount the First Motor

Video coming soon.

  1. Line up a motor (Motor Bag) with the wire end going in first and the spline of the motor on the same side as the short end of the chassis.
  2. Attach the motor to the chassis with two medium bolts (Screw Bag A) and two nuts (Screw Bag C).
1 · Spline toward the short side
2 · Bolt it down

4. Attach the Wheel — Then Repeat the Other Side

Video coming soon.

  1. Find the small black bolt in the small bag of black pieces that came with the motor (Motor Bag).
  2. With a screwdriver, slightly enlarge the hole in the wheel where the small black bolt will be inserted.
  3. Attach the wheel to the spline of the motor with the small black bolt.
  4. Repeat Steps 3 and 4 on the other side of the chassis, so you have two motors and two wheels.

Wheel found in the Electronics Bag.

Wheel + small black bolt
Attached to the spline

Check Your Work

Chassis with two motors, two wheels, and both liftarms attached.

Your chassis should look like this now — two motors, two wheels, both liftarms on the short end.

5. Prepare the Caster

Video coming soon.

  1. Remove the ball from the holder with a screwdriver.
  2. Insert the two long bolts that came in the bag into the two small holes on the inside of the holder.
  3. Replace the ball in the holder. This helps keep the bolts in while you are putting things together.

Caster found in the Electronics Bag.

Start
1 · Remove the ball
2 · Insert the bolts
3 · Replace the ball

6. Build the Caster Arm

  1. Take a 1×9 Liftarm, a ¾ Pin, and a Thin 1×3 Liftarm (LEGO Bag).
  2. Attach the Thin 1×3 Liftarm to the 1×9 Liftarm using the ¾ Pin as shown.
Caster arm assembly

7. Assemble the Caster Onto the Arm

  1. Get the small nuts and the Thick and Thin Spacers out of the Caster bag.
  2. Slide the Thick Spacer onto the caster bolts.
  3. Slide the bolts through the holes in the LEGO.
  4. Slide the Thin Spacer onto the bolts.
  5. Secure all these pieces with the two small nuts.

A spare screw and small nut can be found in Screw Bag F.

Thick spacer → LEGO → thin spacer → small nuts

8. Add the Standoffs

  1. Attach two ½-inch Standoffs (Screw Bag D) to the ends of the LEGO piece as shown.
  2. Attach them with two medium bolts (Screw Bag A).
Two ½-inch standoffs on the caster arm

9. Mount the Wombat

Video coming soon.

  1. Line up the holes on the back of the Wombat with the holes on the back end of the chassis.
Line up the back holes
Seated on the chassis

10. Attach the Caster Assembly

Video coming soon.

  1. Line up the caster assembly with the holes on the back of the robot as shown.
  2. Do this with the robot right side up, balanced on the caster assembly.
  3. Using two small bolts (Screw Bag D), attach the assembly to the chassis.
1 · Line it up, robot right side up
2–3 · Bolt it to the chassis

11. Install the Battery

Video coming soon.

  1. Slide the battery into the back slot of the Wombat case.
Battery + back slot
Installed

Basic Demobot Finished!

Completed Basic Demobot with motors, wheels, caster, Wombat, and battery in place.

Compare your robot to this photo before continuing. Motors, wheels, caster, Wombat, and battery should all be in place.

Phase 3 — Add the Arm and Claw: Servo Demobot

Now you will add two servos: one that raises and lowers an arm, and one that opens and closes a claw. Servo steps must be done in order — especially the servo-horn steps, which set the servo to a known position before you attach anything.

12. Attach the Arm Servo Bracket

Video coming soon.

  1. Line up a servo bracket as shown, then secure it to the chassis with two medium bolts (Screw Bag A) and two nuts (Screw Bag C).
Line up the bracket
Bolt it down

13. Install the Arm Servo

  1. Slide a servo into the servo bracket, wire end first, with the spline toward the front of the robot.
  2. Secure it to the bracket with two medium bolts (Screw Bag A) and two nuts (Screw Bag C).
1 · Wire end first
Spline toward the front
2 · Bolt it in

14. Wind the Arm Servo to Its Stop

Video coming soon.

  1. Place the 1×5 Servo Horn (5-Hole Servo Horn Bag) on the servo as shown — do not bolt it yet.
  2. Rotate the servo head with the 1×5 Servo Horn all the way toward the robot.
  3. Lift the horn off, reset it, and repeat until the servo can no longer turn.
1 · Place the horn
2 · Rotate toward the robot

15. Bolt On the Arm Servo Horn

Video coming soon.

  1. With the horn in the upright position, attach the 1×5 Servo Horn — with a washer under it — to the servo using the small silver bolt that came in the 5-Hole Servo Horn Bag.
Upright, washer under the horn

16. Start the Claw Frame

Video coming soon.

  1. Attach the 1×7 Liftarm (LEGO Claw Bag) to a servo bracket as shown, using a medium bolt (Screw Bag A) and a nut (Screw Bag C). The other hole will be secured in a bit.
  2. Attach an H LEGO piece (LEGO Claw Bag) to the bracket as shown, using two medium bolts (Screw Bag A) and two nuts (Screw Bag C).
1 · 1×7 liftarm on the bracket
2 · Add the H piece

17. Add the 1×5 Liftarm

  1. Attach a 1×5 Liftarm to the H LEGO piece as shown (LEGO Bag).
  2. Attach a black pin to the 1×5 Liftarm (LEGO Bag).
1×5 liftarm + pin

18. Add the 3×7 Bent Liftarm

  1. Attach a 3×7 Bent Liftarm to the 1×5 Liftarm as shown (LEGO Claw Bag).
  2. Push a long black LEGO pin — long end first — all the way through as shown (LEGO Bag).
  3. Attach an axle pin to the end of the 3×7 Bent Liftarm (LEGO Claw Bag).
Bent liftarm, long pin, axle pin

19. Install the Claw Servo

Video coming soon.

  1. Slide a servo into the servo bracket, wire end first, with the spline toward the bent end of the 3×7 Bent Liftarm.
  2. Secure it to the bracket with two medium bolts (Screw Bag A) and two nuts (Screw Bag C).
1 · Wire end first
2 · Spline toward the bent end

20. Wind the Claw Servo to Its Stop

  1. Place the 1×5 Servo Horn (5-Hole Servo Horn Bag) on the servo as shown.
  2. Rotate the servo head with the horn all the way toward the LEGO piece.
  3. Repeat until the servo can no longer turn.
1 · Place the horn
2 · Rotate toward the LEGO piece

21. Bolt On the Claw Servo Horn

  1. Attach a 1×5 Servo Horn — with a washer under it — to the servo using the small silver screw that came in the 5-Hole Servo Horn Bag.
Washer under the horn

22. Attach the Fixed Claw Jaw

Video coming soon.

  1. Attach a Claw Liftarm (LEGO Claw Bag) to the 3×7 Bent Liftarm using an axle pin (LEGO Claw Bag) as shown.
  2. Secure the LEGO pieces together using a long bolt (Screw Bag B) and a nut (Screw Bag C).
1 · Axle pin connection
2 · Bolt + nut

23. Attach the Moving Claw Jaw

  1. Line up a Claw Liftarm (LEGO Claw Bag) on the 1×5 Servo Horn as shown.
  2. Secure it using two long bolts (Screw Bag B) and nuts (Screw Bag C).
1 · Line up on the horn
2 · Two long bolts + nuts

Check Your Work — The Claw Assembly

Completed claw assembly with claw servo, both jaws, and bent liftarm frame.

Your finished claw assembly should look like this: claw servo, both jaws, and the bent liftarm frame.

24. Mount the Claw Assembly to the Arm

Video coming soon.

  1. Line up 3 holes on the arm’s 1×5 Servo Horn with the 1×7 Liftarm from the claw assembly.
  2. Secure it using two long bolts (Screw Bag B) and nuts (Screw Bag C). Make sure the left bolt goes through the claw servo bracket as well.
1 · Line up 3 holes
2 · Left bolt through the bracket

Servo Demobot Finished!

Completed Servo Demobot with driving base, arm servo, and claw servo.

This is the robot you will use for the labs: driving base + arm servo + claw servo.

You're Ready for Lab 1

Put your battery in — it should be charged by now — plug the motor and servo wires into the Wombat, and head to the first lab of your path: C, Python, or Discovery. Keep this guide handy; if a piece ever comes loose, come back to the matching step.

KIPR · Botball Explorer Pre-Lab Exercise · Special thanks to Infosys Foundation USA · © KISS Institute for Practical Robotics 1997–2027