Chapter 5: Building a Drivetrain Pod

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

A. Insert and Fasten a C-Channel

Why do we need to "insert" parts?
An assembly starts empty. You need to "Insert" parts from the parts library — think of it like taking screws and plates out of a toolbox and placing them on the table. After inserting, parts float in space, and you use "Mates" to lock them into the correct position.

Step 1: Switch Tabs

Find the Drivetrain Pod tab at the bottom of the document and click to switch to it.

Step 2: Insert the C-Channel

Insert → Current document → Custom Cuts on Extrusion

Click the Insert button in the toolbar
Select Current document
Find Custom Cuts on Extrusion
Select 1x2x1x30 Aluminum C-Channel with HS Hole
Click the green checkmark to confirm

Animation: Hold Shift to lock inferred points and precisely select the square hole center

        VEX Assembly Tip

        Most mates require aligning to the center of a square hole. Hold the Shift key to lock inferred points, making it easy to precisely select the center of a square hole.

Step 3: Create the First Fastened Mate

Animation: Fastening the C-Channel to the assembly origin

Select the Origin and the C-Channel square hole center to create a Fastened Mate

Click the Mate tool
For the first connector, select the assembly's Origin
For the second connector, select the center of a square hole on the C-Channel
If the orientation is wrong, click Reorient secondary axis to adjust
Click the green checkmark to confirm

✅

Checkpoint 1: Is the C-Channel fastened to the origin?

The C-Channel should be firmly fixed at the assembly origin, not floating.

No worries, many people run into issues with this step!

If the C-Channel didn't appear in the assembly: 1) Make sure you clicked the green checkmark to confirm insertion 2) Press F to see if the part flew out of view 3) Check whether the part name appears in the instance list on the left

Common Issues

C-Channel orientation is wrong? — In the Mate dialog, click Flip primary axis or Reorient secondary axis to adjust
Can't select the square hole center? — Remember to hold Shift to lock the inferred point, then slowly move to the center of the square hole

B. Install the Motor and Second C-Channel

Step 4: Insert the Smart Motor

Animation: Inserting the Smart Motor from the parts library

Insert the Smart Motor (18:1) from the VEX V5 parts library

Click Insert → Other documents
Find your VEX V5 Parts label
Open VEX V5 - Electronics
Select Smart Motor (18:1)
Click the green checkmark to confirm

Step 5: Fasten the Motor to the C-Channel

Create a Fastened mate
First connector: the motor's threaded mounting boss
Second connector: a square hole on the C-Channel (aligned with the large round hole)
Use Reorient or Flip to adjust the motor orientation
Confirm the motor sits flush against the C-Channel

Step 6: Insert the Second C-Channel

Animation: Inserting and configuring the second C-Channel

Click Insert → Other documents → VEX V5 Parts
Open VEX V5 - Structure
Select C-Channel Configurable
Configure as 15 inches (30 holes), model 1x2x1x30 Aluminum
Insert and fasten to the correct position with a Fastened mate

✅

Checkpoint 2: Are the motor and second C-Channel installed?

You should see a motor mounted on the first C-Channel and the second C-Channel in place.

No worries, many people run into issues with this step!

If the motor orientation is wrong: 1) Click the Reorient secondary axis button a few more times 2) Try Flip primary axis 3) There are only 4 possible orientation combinations — try each one until it's right

Common Issues

Can't find the parts library? — Make sure you added the "VEX V5 Parts" label in Chapter 4
Motor position is wrong? — Refer to the completed model in the Complete Drivetrain tab to compare motor placement

C. Install Standoffs and Bearings

Step 7: Insert Standoffs

Animation: Inserting standoffs with screws from the parts library

Animation: Inserting and mounting standoffs to the C-Channel

4 standoffs connect the two C-Channels

Click Insert → Other documents → VEX V5 Parts
Open VEX V5 - Spacers and Standoffs → Assemblies
Select #8-32 Standoff with Screw(s)
Configure the length to 2.5 inches
Insert 4 of them

Step 8: Fasten Standoffs to the C-Channel Corners

Animation: Continuing to insert and fasten standoffs to the C-Channel corners

Create a Fastened mate for each standoff
Connect the bottom of each standoff to the four corner square holes on the first C-Channel

Step 9: Fasten the Second C-Channel to the Standoff Tops

Animation: Fastening the second C-Channel to the tops of the standoffs

Create a Fastened mate
Align the second C-Channel to the tops of the 4 standoffs
The two C-Channels should now be connected in parallel by the standoffs

Step 10: Insert Bearings

Animation: Inserting bearings into the C-Channel

Click Insert → VEX V5 - Bearing, Collars, and Inserts → Assemblies
Select High Strength Shaft Bearing with Screws
Insert 3 bearings
Use Fastened mates to fix the bearings to the designated positions on the C-Channel

Step 10b: Fasten Each Bearing

Animation: Using Fastened mate to fix the first bearing

Animation: Fastening the remaining two bearings the same way

Create a Fastened mate for the first bearing, aligned to the round hole on the C-Channel
Repeat for the second and third bearings at their corresponding positions
Confirm all 3 bearings are in the correct holes

✅

Checkpoint 3: Is the frame built?

Check: Two C-Channels + 4 standoffs + 3 bearings, all correctly installed.

Common Issues

Wrong standoff length? — After inserting, you can modify the Configuration in the left panel. Confirm it's set to 2.5 inches
Second C-Channel won't align? — Fasten one corner first, then fasten the remaining corners one by one
Not sure about bearing positions? — Refer to the completed model in the Complete Drivetrain tab

D. Install Shafts, Wheels, and Chain

Step 11: Insert Shafts

Animation: Inserting high strength shafts into the bearings

Shafts pass through bearings, wheels mount on the outer ends

Click Insert → VEX V5 - Shafts
Select High Strength Shaft
Insert two: one 3.25 inch and one 2.5 inch
Use Fastened mates to fix the shafts to the bearing centers

Animation: Fastening shafts to bearing centers

Step 12: Install Wheels

Animation: Inserting 4-inch omni wheels onto the shafts

Click Insert → VEX V5 - Wheels & Rollers
Select 4" Omni Wheel
Insert 2
Use Fastened mates to fix the wheels to the shafts on the outside of the bearings

Animation: Fastening omni wheels to the shafts

Step 13: Install Spacers

Animation: Inserting high strength shaft spacers from the parts library

Click Insert → VEX V5 - Spacers and Standoffs
Select High Strength Shaft Spacer, configure as 1/2 inch
Insert 2
Use Fastened mates to fix the spacers to the shafts next to the wheels

Animation: Fastening spacers to the shafts

Step 14: Install Sprockets and Chain

Animation: Inserting sprockets and chain and completing the assembly

Sprockets and chain transfer motor power to the wheels

Click Insert → VEX V5 - Sprockets and Chain
Insert 18T HS Sprocket (18-tooth high strength sprocket) x 2
Insert 70 Link Chain, configured for 18T, 18T, 10 inch C2C
Use Fastened mates to fix the sprockets next to the spacers
Use a Fastened mate to fix the chain to the sprockets

Animation: Fastening sprockets to the shafts

Animation: Fastening the chain to the sprockets

Step 15: Final Details

Animation: Copying an existing spacer and fastening it to a new position

Animation: Inserting a 0.125 inch (1/8") spacer

Copy and paste a spacer: Select an existing spacer → Copy → Paste, then change the configuration to 1/8 inch
Use a Fastened mate to fix it in the correct position
Insert 2 screws to secure the motor

Animation: Inserting 8-32 star drive screws to secure the motor

Animation: Fastening motor screws with Fastened mate

✅

Checkpoint 4: Is the sub-assembly complete?

Your Drivetrain Pod should contain: C-Channel x 2, motor x 1, standoffs x 4, bearings x 3, shafts x 2, wheels x 2, spacers, sprockets x 2, chain x 1. Compare with the reference model in the Complete Drivetrain tab!

Common Issues

Chain shape looks wrong? — Make sure the C2C (Center to Center) distance in the chain configuration is correct — it should be 10 inches
Wheels won't spin? — This is normal because we're using Fastened mates (fixed). If you wanted the wheels to spin, you'd use a Revolute mate, but for this tutorial, fixed is fine
Too many parts to remember positions? — Refer to the completed model in the Complete Drivetrain tab at any time

        What You Learned in This Chapter
        Fastened mate locks parts to a specific position
Hold Shift to select the mate connector at the center of a square hole
Find and insert parts from the VEX V5 Parts label

      