πŸ“š Contents

πŸ“– Cam Designer User Documentation

Getting Started

Welcome to Cam Designer! This comprehensive tool allows you to design and analyze valve train systems with detailed geometric calculations and performance visualization.

System Requirements

πŸ’‘ Tip: For best experience, use a desktop or tablet. Mobile devices are supported but may have limited screen space for visualization.

πŸ“ˆ Understanding Motion Curves

When you design a cam profile in Cam Designer, the software displays four curves on the Motion Design graph: Lift, Velocity, Acceleration, and Jerk. These four curves are not independent β€” each one is derived from the one before it. Together, they give you a complete picture of how a valve (or any follower) moves as the cam rotates.

This section explains what each curve means, why it matters, and how to read them β€” even if you've never worked with calculus or motion analysis before.

Motion Design graph showing Lift, Velocity, Acceleration, and Jerk curves with labeled parameters

Designing Your Motion Profile

The annotated image above shows the Motion Design page β€” where all cam profile design happens. Before diving into the theory behind each curve, here is how the software works and how to use it effectively.

Reading the Graph

The horizontal axis represents cam rotation in degrees. Zero degrees is at the point of maximum lift (the nose of the cam). Negative angles are the rise side (valve opening) and positive angles are the fall side (valve closing). The numbers along the baseline are crank rotation degrees.

Because the four curves have very different magnitudes β€” lift might be 10 mm while acceleration is 0.002 mm/degΒ² β€” each curve has its own scale. The scale legends are shown on the left side of the graph, and you can adjust each one independently using the Graph Scales dropdown in the left panel.

The Control Panel

Below the graph, the control panel has three rows of input fields arranged in two groups β€” Rise (left) and Fall (right) β€” with a center column at 0Β°. The small nodes visible on the acceleration curve are the control points that correspond to these input fields:

The duration at lash β€” the total angular width of the cam event β€” is the sum of all X-row values on each side. The angular separation between the rise and fall ramp ends is defined by βˆ’R9_X + F9_X.

The Design Workflow: Update and Solve

After editing parameter fields, use the two buttons in the left panel to recalculate the profile:

⚠️ Important: Before pressing Solve, use Update repeatedly and adjust your parameters until the lift and velocity curves are as close to zero at the ends as you can get them. The solver works by making corrections to achieve perfect closure β€” if your profile is far from closing, the solver may need to make large adjustments that distort the shape you intended. Getting close first gives the solver less work to do and preserves your design intent.
πŸ’‘ Workflow tip: A good rhythm is: edit a parameter β†’ press Update β†’ check the curves β†’ repeat. Once you are satisfied with the shape and the lift and velocity are nearly zero at the ends, press Solve for a final, valid profile. If the solver changes the R15_R19 or F15_F19 duration values significantly, your profile was far from closing β€” go back and adjust your acceleration magnitudes or durations.

Save, Load, and Export Lift

All files are saved to and loaded from your local computer using your browser's standard download and file-picker dialogs. Nothing is stored on the server.

πŸ’‘ Organizing your files: We recommend creating a folder on your computer to keep your cam files organized. As you use more features, more file types will accumulate β€” keeping them separated makes it easy to find what you need. For example: 
C:\CamDesigns\
  β”œβ”€β”€ Designs\          ← Saved design parameter files (.json from Motion Design β†’ Save)
  β”œβ”€β”€ LiftProfiles\     ← Exported lift profile files (.json from Motion Design β†’ Export Lift)
  └── FlowConfigs\      ← Flow analysis configurations (.json from Flow Analysis β†’ Save)
When your browser asks where to save a file, navigate to the appropriate subfolder. This keeps your design files, lift exports, and flow configurations separate and easy to find later.

The Big Picture: Position β†’ Speed β†’ Force β†’ Shock

Think of the four curves as answering four increasingly detailed questions about the follower's motion:

Curve Question It Answers Everyday Example
Lift Where is the follower right now? Your car's odometer β€” how far have you gone?
Velocity How fast is the follower moving? Your speedometer β€” how fast are you going?
Acceleration How quickly is the speed changing? The push you feel when the driver hits the gas or brakes.
Jerk How suddenly does the push change? The jolt when someone stomps on the brakes versus squeezing them smoothly.
πŸš— Driving analogy: Imagine you're a passenger in a car. Lift is where you are on the road. Velocity is how fast the car is going. Acceleration is the force that pushes you into the seat (or forward into the seatbelt). Jerk is how abruptly that push starts β€” a gentle ramp-up feels smooth; a sudden slam feels rough. A good cam profile is like a skilled driver: it gets you there quickly but without jarring transitions.

Lift (Displacement)

What It Is

Lift is the most intuitive curve. It shows how far the follower has moved away from the base circle at each angle of cam rotation. When lift is zero, the follower is sitting on the base circle and the valve is closed. At maximum lift, the valve is fully open.

What to Look For

πŸ”‘ Key point: Lift is the curve most people understand intuitively β€” it's simply "how high is the valve right now?" But lift alone doesn't tell you whether the motion is smooth or whether it will create excessive forces. That's what the other curves are for.

Velocity

What It Is

Velocity is the rate of change of lift. It tells you how fast the follower is moving at each point. Mathematically, velocity is the first derivative of lift with respect to cam angle.

When velocity is positive, the follower is moving upward (valve opening). When velocity is negative, the follower is moving downward (valve closing). When velocity is zero, the follower is momentarily stopped β€” this happens at the base circle and at maximum lift (the follower has to stop before reversing direction).

How to Read It

Why It Matters

In an engine, the velocity of the follower determines the oil flow rate through the valve opening and affects how quickly the valve clears the seat. Very high velocity at the seating point (when the valve closes) causes the valve to slam into the seat, leading to excessive noise, seat wear, and potential valve failure.

⚠️ Important: The velocity should reach zero smoothly at the closing point. If it doesn't, the valve will hit its seat at speed β€” this is called seating velocity and is one of the most critical parameters in cam design.

Acceleration

What It Is

Acceleration is the rate of change of velocity β€” the second derivative of lift. It tells you how quickly the follower is speeding up or slowing down.

This is the most important curve for cam designers because acceleration is directly proportional to force. Newton's second law (F = m Γ— a) means that every peak in the acceleration curve corresponds to a peak force on the valve train components.

How to Read It

Why It Matters

The magnitude of acceleration directly determines:

πŸ”‘ Key point: The acceleration curve is the cam designer's primary tool. You are essentially designing the acceleration shape, and the lift curve is a result of that design. In Cam Designer, you directly edit the acceleration control points and the software integrates them to produce the lift.

The Relationship: Acceleration β†’ Velocity β†’ Lift

The mathematical relationship flows in both directions: 

Going down (differentiation):
    Lift β†’ Velocity β†’ Acceleration β†’ Jerk

Going up (integration):
    Jerk β†’ Acceleration β†’ Velocity β†’ Lift

In Cam Designer, you define the acceleration shape using control points. The software then:

  1. Integrates acceleration once to compute velocity.
  2. Integrates velocity once more to compute lift.
  3. Differentiates acceleration to compute jerk.

This is why the acceleration curve is the starting point β€” everything else follows from it.

Jerk

What It Is

Jerk is the rate of change of acceleration β€” the third derivative of lift. It measures how abruptly the forces change. A sudden jump in acceleration produces a spike in jerk.

How to Read It

Why It Matters

High jerk causes:

πŸš— Driving analogy: Imagine pressing the brake pedal. If you squeeze it gently and progressively, the car slows smoothly (low jerk). If you stomp on it instantly, you and your passengers lurch forward violently (high jerk). The car decelerates the same amount either way, but the comfort and mechanical stress are very different.
πŸ’‘ Tip: The Sharpness controls in Cam Designer let you adjust how rounded the acceleration curve corners are. Lower sharpness values produce rounder corners and lower jerk. Higher values produce sharper corners and higher jerk, but pack more area under the acceleration curve β€” which means more lift for the same duration.

How the Four Curves Are Connected

The four curves form a chain. Each curve is the slope (rate of change) of the one above it:

If This Curve Is... Then the Next Curve Is...
Lift is increasing Velocity is positive
Lift is flat (at peak or on base circle) Velocity is zero
Lift is decreasing Velocity is negative
Velocity is increasing Acceleration is positive
Velocity is at its peak Acceleration is zero (crossing)
Velocity is decreasing Acceleration is negative
Acceleration is changing gradually Jerk is small
Acceleration has a sharp corner Jerk has a spike
πŸ”‘ Key point: You can always verify the curves are correct by checking these relationships. If lift is at its steepest and velocity isn't at its peak, something is wrong. These cross-checks are a powerful debugging tool.

What Makes a Good Cam Profile

A well-designed cam profile balances competing goals: maximum valve opening for airflow versus minimum stress and vibration. Here are practical guidelines:

Smooth Transitions

The acceleration curve should have smooth, rounded transitions between segments. Sharp corners in the acceleration create jerk spikes, which cause noise, vibration, and shock loading. Use lower sharpness values (0.3–0.6) for smoother transitions, or higher values (0.7–0.9) when you need to pack more lift into a given duration.

Controlled Seating Velocity

Watch the velocity curve at the closing ramp (the last part of the fall side, near the base circle). The velocity must be small when the valve contacts the seat. A typical target is less than 0.05 mm/deg for passenger car applications and may be higher for racing applications.

Negative Acceleration vs. Spring Force

The negative acceleration region determines the minimum spring force required. At any given RPM, the spring must exert more force than the inertial load created by negative acceleration. If the spring is too weak, the follower separates from the cam β€” this is valve float.

⚠️ Design rule: The ratio of spring force to inertial load (at peak RPM) should be at least 1.2 to 1.5 for reliable operation. Use the Dynamics page to check this.

Common Problems and What They Look Like

Symptom What You See on the Graph What It Means
Lift doesn't return to zero Lift curve ends above or below the baseline The profile isn't closed. Press Solve or adjust durations.
Huge jerk spikes Jerk curve has very tall, narrow spikes at acceleration transitions Acceleration corners are too sharp. Reduce sharpness values.
Velocity doesn't reach zero at closure Velocity curve has a non-zero value at the end of the event The follower would hit the seat at speed. Press Solve to fix.
Negative lift values Lift curve dips below zero The follower would need to pass through the base circle β€” physically impossible. Adjust acceleration magnitudes.
Flat spot on lift curve Lift curve has a horizontal section in the middle Velocity is zero in the middle of the event. Usually caused by acceleration crossing zero in an unintended way.

Motion Curves Quick Reference

Curve Units What It Tells You Design Impact
Lift mm How far the valve is open Airflow, engine breathing
Velocity mm/deg How fast the valve is moving Seating impact, oil flow
Acceleration mm/degΒ² Force on the valve train Spring requirements, contact stress, component loads
Jerk mm/degΒ³ Abruptness of force changes Vibration, noise, shock loads
πŸ’‘ Remember: You design the acceleration. The software computes lift, velocity, and jerk from it. Acceleration is the curve to focus on β€” the others are consequences.

🌬️ Flow Analysis

The Flow Analysis page evaluates how effectively your cam profile opens the valve for airflow. It combines your lift profile, valve geometry, engine dimensions, and optional flow bench data to calculate curtain area, time-area indices, and 720Β° breathing charts.

Key Concepts

Two Analysis Tiers

Formulas

Valve curtain area (perpendicular to flow):
  A_curtain = Ο€ Γ— D_valve Γ— L Γ— cos(seat_angle)

Total curtain area (all valves of this type):
  A_total = N_valves Γ— A_curtain

Bore area (reference):
  A_bore = Ο€/4 Γ— D_boreΒ²

Geometric time-area index:
  TA = Ξ£( A_curtain(ΞΈ) Γ— Δθ )  over all cam angles where lift > 0

Mean curtain area during event:
  A_mean = TA / duration

Curtain-to-bore ratio at peak lift:
  CBR = A_curtain_peak / A_bore Γ— 100%

The Valve Timing Diagram

The valve timing diagram shows both intake and exhaust lift curves plotted together over a full 720Β° crank cycle. The horizontal axis spans from 0Β° to 720Β° with 0Β° at TDC overlap (the point where both valves are open between the exhaust and intake strokes). Four background bands show the engine strokes: Intake, Compression, Power, and Exhaust.

This chart lets you visualize overlap (both valves open near TDC), relative event duration, and how each valve event aligns with piston motion. The intake and exhaust centerlines from the sidebar control where each profile is positioned.

Save and Load

The Flow Analysis page has Save and Load buttons that work the same way as on the Motion Design page β€” all data stays on your local computer. Save downloads a .json configuration file containing all sidebar inputs (valve sizes, engine dimensions, cam timing, and flow bench data). Load restores them.

Valve Train Design

The Valve Train design page allows you to specify different valve train configurations and visualize the cam profile.

Supported Types

Key Parameters

Each valve train type has specific parameters that define its geometry:

Parameter Unit Description
Base Circle Radius mm Distance from cam center to zero-lift point
Follower Radius/Diameter mm Size of the follower element
Pivot Distances mm Rocker arm pivot locations

Visualization Controls

Once you load a cam profile, you can control how it's visualized:

Cam Rotation

Adjust the rotation angle to see how the follower contacts the cam at different positions.

Follower Width

Adjust the displayed follower width to visualize contact coverage. The distance indicators show how far the contact point is from the follower edges.

⚠️ Important: If the contact point goes outside the follower width, it indicates the follower is too narrow for the cam profile.

Curvature Visualization

Green lines show the radius of curvature at each point:

Data Analysis

The Data Table page provides comprehensive analysis of your cam profile:

Available Data

Export Options

Export your analysis data in multiple formats:

Moment of Inertia Calculator

Calculate the rotational inertia of your valve train assembly:

How It Works

The calculator uses the formula:

I = Ξ£(m Γ— rΒ²)

Where:
  I = moment of inertia
  m = mass of component
  r = distance from rotation axis

Input Parameters

πŸ’‘ Tip: Increasing rocker arm length or mass has a squared effect on inertia, so small reductions can significantly improve performance.

Troubleshooting

Page Won't Load Data

Check:

Contact Point Goes Outside Follower

Solutions:

Unusual Curvature Patterns

This may indicate:

Support & Feedback

Have questions or found a bug?

Documentation Version 1.0 | Last Updated: 2026

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