Lesson 3 · Build The Rotating Base

Suggested Time: 30-60 minutes

Lesson Plan

Materials

Need materials? Purchase the Barnabas Robot Arm at our e-store.

Classroom sets available. Contact us at info@barnabasrobotics.com to inquire.

Lesson Overview

In this lesson we will assemble the rotating base / turret.

Instructions

STEP 1. Build Main Body Bottom Plate

Assemble main body bottom plate using:

  • 1 x Servo Horn
  • 2 x Servo Screws
  • 1 x Acrylic Piece
Top View Bottom View

STEP 2. Build Left (Lift) Motor Assembly

Assemble left (lift) motor mount using:

  • 1 x Servo Motor
  • 2 x M3x10 Screws
  • 2 x Acrylic Pieces

Assemble small servo arm using:

  • 2 x Servo Screws
  • 1 x Servo Horn
  • 1 x Acrylic Piece

Attach small servo arm using:

  • 1 x Servo Screw

IMPORTANT: Note that the servo motor can only move 180 degrees. Make sure that the arm can turn fully between the two positions shown below before fastening the screw. You may need to take the servo coupling off of the servo motor shaft and reposition it a few times to get it right.

Position 1 Position 2

STEP 3. Build Right (Extend) Motor Assembly

Assemble right (extend) motor mount using:

  • 1 x Servo Motor
  • 2 x M3x10 Screws
  • 2 x Acrylic Pieces

Top View Bottom View

Assemble large servo arm using:

  • 2 x Servo Screws
  • 1 x Servo Horn
  • 1 x Acrylic Piece
Top View Bottom View

Attach large servo arm using:

  • 1 x Servo Screw

IMPORTANT: Note that the servo motor can only move 180 degrees. Make sure that the arm can turn fully between the two positions shown below before fastening the screw. You may need to take the servo coupling off of the servo motor shaft and reposition it a few times to get it right.

Position 1 Position 2

STEP 4. Build Main Arm Support

Assemble main arm support using:

  • 1 x M3x10 Screw
  • 2 x Acrylic Pieces

IMPORTANT: Do not overtighten. Make sure that the joint can move easily. If it is too tight, your motors will not be able to move the joint during robot arm operation.

STEP 5. Assemble Main Body

You will need:

  • 1 x Left (Lift) Motor Assembly
  • 1 x Right (Extend) Motor Assembly
  • 1 x Main Body Bottom Plate
  • 1 x Main Arm Support
  • 1 x Acrylic Piece - Curved Joiner
  • 1 x Acrylic Piece - Straight Joiner
  • 4 x M3x12 Screws
  • 4 x M3 Nuts (Regular)

IMPORTANT — FOLLOW STEPS 1–6 IN ORDER

Assemble the main body in the exact order shown in the photos below. Do not try to snap or force all of the pieces together at once.

The acrylic tabs should fit into the matching slots with gentle pressure. If a piece does not fit easily, stop and check its orientation against the photo before continuing. Forcing a tab into the wrong slot or bending the piece can cause it to break.

5A. Join the first two pieces

Connect the Left (Lift) Motor Assembly and Straight Joiner as shown in Step 1, and fasten it together by sliding a M3 nut into the slot and installing the M3x12 screw. Tighten the screw only until the joint is secure.

Then carefully position the Main Arm Support and Curved Joiner as shown in Step 2. Make sure that the orientation of the tabs matches the one in the photo.

STEP 1 STEP 2

5B. Fasten Curved Joiner and position the Bottom Plate

Fasten the Curved Joiner using an M3x12 Screw + Nut as shown in Step 3.

Next, position the Main Body Bottom Plate, so that it connects all the pieces together, as shown in STEP 4.

STEP 3 STEP 4

5C. Finish the assembly

While holding everything together, fit the Right (Extend) Motor Assembly.

Do not force the part into place. If the tabs do not line up easily, compare your assembly with the previous photo before continuing.

STEP 5 STEP 6

Once the final piece is correctly positioned, fasten it together by sliding the M3 nuts into the slots and installing the M3x12 screws. Tighten the screws only until the joints are secure.

When complete, your turret should look like the photos below.

Front View Back View

STEP 6. Attach Main Body To Motor

Attach the main body to the base servo motor using:

  • 1 x Servo Screw

IMPORTANT: Note that the servo motor can only move 180 degrees. Make sure that the arm can turn fully between the two positions shown below before fastening the screw. You may need to take the servo coupling off of the servo motor shaft and reposition it a few times to get it right.

Position 1 Position 2

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