Chapter 6: Assembling the Full Drivetrain

Open your copied document in Onshape and switch to the Complete Drivetrain tab

A. Inserting Parts

Step 1: Switch to the Complete Drivetrain Tab

Find the Complete Drivetrain tab at the bottom of the document and click to switch to it. This tab is where you'll assemble the final complete drivetrain.

Step 2: Insert Structural Parts and Pods

Animation: Inserting structural parts and Pods into the complete assembly

Insert Angle, Drivetrain Pod, and U-Channel

Click Insert → Current Document
Insert 2x2x20 Aluminum Angle x 1
Insert Drivetrain Pod (the sub-assembly you completed in Chapter 5) x 2

Step 3: Insert U-Channel

Animation: Inserting a U-Channel from the parts library and configuring its length

Click Insert → Other documents → VEX V5 Parts
Open VEX V5 - Structure
Select U-Channel Configurable
Configure it to 10 inches

Step 4: Fix U-Channel to Origin

Animation: Fixing the U-Channel to the assembly origin

U-Channel fixed at the assembly origin

Create a Fastened mate
Fix the U-Channel to the assembly's Origin

✅

Checkpoint 1: Are all parts inserted?

You should see: 1 U-Channel (fixed to origin), 2 Drivetrain Pods, and 1 Aluminum Angle.

⚠️ Common Issues

Can't find Drivetrain Pod? — Make sure you completed the Pod assembly in Chapter 5. It should appear in the Current Document list.
U-Channel length is wrong? — After inserting, check the Configuration in the left panel and confirm it's set to 10 inches.

B. Connecting the Two Pods

Step 5: Attach the Right Pod

Animation: Attaching the right Drivetrain Pod to the U-Channel

Right Pod connected to the rear-right of the U-Channel

Create a Fastened mate
Connect the right Drivetrain Pod to the rear-right of the U-Channel
Make sure the Pod's wheels face outward

Step 6: Attach the Left Pod

Animation: Mirror-installing the left Drivetrain Pod

The left Pod needs to be rotated 180° first (for mirror placement)
When creating the Fastened mate, use Flip primary axis or manually rotate
Connect the left Pod to the left side of the U-Channel
Confirm both Pods are symmetrical

Step 7: Attach the Front Angle

Animation: Fixing the Aluminum Angle to the front of the drivetrain

Create a Fastened mate
Fix the 2x2x20 Aluminum Angle to the front of the drivetrain
The Angle spans both Pods, adding structural rigidity

✅

Checkpoint 2: Are both Pods symmetrically installed?

Viewed from the top, the drivetrain should be left-right symmetrical. The wheels on both Pods face outward (left and right), and the Angle connects them at the front.

⚠️ Common Issues

Left Pod facing the wrong way? — Use Flip primary axis in the Mate dialog to rotate 180°, or delete the mate and recreate it.
Pods aren't symmetrical? — Use the View cube to switch to Top view and verify both Pods are mirror images of each other.

C. Adding Bolts and Nuts

Step 8: Insert Custom Spacers

Animation: Inserting and fixing custom spacers

Spacers fill the gap between the two Pods

Insert 0.875-inch custom spacers from the current document or parts library
You'll need 6 total
Use Fastened mates to fix the spacers at the connection points between the two Pods

Animation: Copying the spacer to the second position and fixing it

Animation: Repeat the process to install all 6 spacers

Step 9: Insert Screws

Animation: Inserting and fixing screws

Insert 1-1/4 inch screws and 1-1/2 inch screws
Use Fastened mates to fix the screws on top of the spacers
You can fix one first, then copy and paste to the remaining positions

Animation: Copying and pasting screws to remaining connection points

Animation: Installing the last two screws at the remaining positions

Step 10: Install Nylock Nuts

Animation: Installing nylock nuts on the bottom of the screws

Done! A complete VEX V5 tank drivetrain

Click Insert → VEX V5 Parts Library
Find #8-32 Nylock Nut
Insert 6 of them
Use Fastened mates to fix each nut to the bottom of its corresponding screw

Animation: Fixing all nuts to the bottom of the screws

🎉

Checkpoint 3: Drivetrain assembly complete!

Congratulations! Your complete drivetrain should include two Pods, a U-Channel, an Angle, spacers, screws, and nuts. Compare it with the reference model to make sure nothing is missing.

⚠️ Common Issues

Screw length not right? — Make sure you're using the correct screw length (1-1/4" or 1-1/2"). Different positions require different lengths.
Nuts in the wrong position? — Nylock nuts should be fixed at the bottom of the screws after they pass through the parts, serving as locking fasteners.

Summary

🏁 Congratulations on completing the drivetrain CAD model!

The drivetrain is just the starting point for your robot. From here, you can continue adding:

Control System — VEX V5 Brain, battery, controller receiver
More Motors — To drive additional mechanisms (intake, launcher, etc.)
Reinforcement — Extra structural supports to make the drivetrain more rigid
Scoring Mechanisms — Design intake, launcher, and other mechanisms based on game requirements

Keep exploring Onshape and turn your ideas into reality!

        What You Learned in This Chapter
        Sub-assemblies can be reused multiple times
Rotating 180° before mating creates a symmetric installation
Copy and paste speeds up placing repeated parts

      