Chapter 19: Scoring Mechanism Design

This chapter doesn't teach specific Onshape operations -- you've already learned those. Instead, it teaches design thinking: given a competition task, how do you choose the right mechanism? How do you go from idea to parts?

A. Common VEX Scoring Mechanism Types

Below are the most common scoring mechanisms in VEX V5RC competitions. Each has its own use cases and difficulty level -- choose based on your competition task and team capabilities.

Mechanism Type	Use Case	Key Parts	Difficulty
Simple Plow / Pusher	Push game elements into target zones	C-Channel + plate	⭐ Beginner
Roller Intake	Pick up balls, discs, and other round elements	Motor + roller + chain	⭐⭐ Intermediate
Claw / Gripper	Grab blocks and objects	Motor + linkage + clamp plates	⭐⭐ Intermediate
Catapult	Launch game elements over long distances	Motor + spring + linkage	⭐⭐⭐ Upper-Intermediate
Flywheel Launcher	High-speed ball shooting	High-speed motor + flywheel	⭐⭐⭐⭐ Advanced
Lift Mechanism	Raise / stack elements	Motor + rail + chain	⭐⭐⭐⭐ Advanced

💡 How to Choose?

First-time design: Go with a plow or roller intake -- simple and reliable
Some experience: Try a claw or catapult
Going for high scores: Flywheel and lift mechanisms can produce more powerful robots, but they're also harder to tune
General advice: A reliable simple mechanism > an unreliable complex one

✅

Checkpoint 1: Have you decided which mechanism to build?

Based on your competition task and team capabilities, pick a mechanism type. If you're unsure, start with the simplest plow or roller intake.

B. Design Thinking: From Function to Parts

No matter which mechanism you chose, the design process is the same. Follow these 6 steps:

Step 1: Define the Function

What exactly does this mechanism need to do? Break it down into specific actions.

For example, an intake: Catch ball → Transport inward → Pass to launcher

Step 2: Choose the Motion Type

What kind of motion does each action need?

Rotation -- Rollers, flywheels, catapult arms
Linear motion -- Lifts, push rods
Swinging -- Claws, pushers

Step 3: Choose the Drive Method

Direct drive -- Simplest: motor connects directly to the shaft
Gear reduction / speed-up -- When you need more torque or higher speed
Chain drive -- For transmitting power over longer distances

Step 4: Sketch It Out

Draw side view and top view on paper with key dimensions. Think about:

Where will the mechanism mount on the drivetrain?
How much range of motion does it have? Will it collide with other parts?
Where does the motor go? Is the wiring convenient?

Step 5: Select Parts

Find suitable parts from the VEX V5 Parts library. Most mechanisms can be built with these standard components:

C-Channel (structural frame)
Shafts and bearings (rotating parts)
Chain and sprockets (power transmission)
Bolts, nuts, spacers (fasteners)

Step 6: Model It in Onshape

Simple mechanisms: Build directly in the assembly using off-the-shelf parts
Complex mechanisms: Design custom parts in a Part Studio first (Chapters 7-8), then assemble into Full Assembly

C. Practical Example: Designing a Simple Roller Intake

Here's a design guide for a Roller Intake -- not step-by-step instructions, but what you need and how to connect it.

Parts You'll Need

2 C-Channels -- Side frame plates for the intake
1 motor -- To drive the roller
1 shaft -- Runs through both side plates as the roller's axis of rotation
Roller / wheels -- Mounted on the shaft; contacts and pulls in game elements
2 bearings -- Mounted on the side plates to support shaft rotation

Assembly Relationships (Mates)

Frame → Drivetrain: Fastened mate
Motor → Frame: Fastened mate
Shaft → Bearings: Revolute mate (allows rotation)
Roller / wheels → Shaft: Fastened mate

Finding inspiration: Search the Onshape community for "VEX intake" or "VEX roller intake" to see how others do it. Learn from their structures, then implement it your own way.

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Checkpoint 2: Have you tried building a simple mechanism in Onshape?

It doesn't need to be perfect -- just get the basic structure in place and make sure the connections between parts are correct.

D. Design Review Checklist

After building your mechanism, run through this checklist:

☐ Can the mechanism perform its intended function? (Mentally simulate the motion)
☐ Are there no interferences between parts? (Check with bottom view and section view)
☐ Is the motor position reasonable? Is wiring convenient?
☐ Is the overall size still within 18" x 18" x 18"?
☐ Is the part count reasonable? Simpler is more reliable
☐ Is the center of gravity reasonable? Will the robot be top-heavy?

✅

Checkpoint 3: Have you reviewed your design with the checklist?

Go through each item above. If you find any issues, go back and fix them -- that's the iteration process.

        What You Learned in This Chapter
        Think before you build -- Go from function → motion → drive → parts, refining step by step
Start simple, iterate to improve -- A reliable simple mechanism is better than an unreliable complex one
Reference community examples -- Don't reinvent the wheel; stand on the shoulders of others

      