Spur Gear Dimensions Calculator
Spur gears are the most common type of gear, characterized by straight teeth mounted on a parallel axis. They are used to transmit motion and power between two parallel shafts. Understanding their precise dimensions is crucial for proper design, manufacturing, and assembly in various mechanical systems, from simple toys to complex industrial machinery.
Key Spur Gear Terminology:
- Module (m): A fundamental unit of size for gears, representing the ratio of the reference diameter to the number of teeth. It's a standardized value that ensures interchangeability.
- Number of Teeth (z): The total count of teeth on the gear.
- Reference Diameter (Pitch Diameter, d): The diameter of the pitch circle, which is the theoretical circle where two mating gears make contact. It's the basis for most gear calculations.
- Outside Diameter (da): The largest diameter of the gear, measured across the tips of the teeth.
- Root Diameter (df): The smallest diameter of the gear, measured at the bottom of the tooth spaces.
- Addendum (ha): The radial distance from the pitch circle to the top of the tooth.
- Dedendum (hf): The radial distance from the pitch circle to the bottom of the tooth space.
- Whole Depth (h): The total radial depth of the tooth, from tip to root.
- Circular Pitch (P): The distance between corresponding points on adjacent teeth, measured along the pitch circle.
- Tooth Thickness (s): The width of a tooth measured along the pitch circle.
- Space Width (e): The width of the tooth space measured along the pitch circle.
This calculator helps you determine the critical dimensions of a standard spur gear based on its Module and Number of Teeth. These calculations typically assume a standard pressure angle (commonly 20 degrees) and standard addendum/dedendum values (addendum = module, dedendum = 1.25 * module).
mm
Calculated Dimensions:
Reference Diameter (Pitch Diameter):
mm
Outside Diameter:
mm
Root Diameter:
mm
Addendum:
mm
Dedendum:
mm
Whole Depth:
mm
Circular Pitch:
mm
Tooth Thickness:
mm
Space Width:
mm
How to Use the Calculator:
- Enter Module (m): Input the module value for your gear. This is a standard sizing parameter, often in millimeters.
- Enter Number of Teeth (z): Input the total number of teeth on the gear.
- Click "Calculate Gear Dimensions": The calculator will instantly display all the derived dimensions based on standard gear formulas.
Example Calculation:
Let's calculate the dimensions for a spur gear with a Module of 2 mm and 30 teeth:
- Module (m) = 2 mm
- Number of Teeth (z) = 30
- Reference Diameter (d) = m * z = 2 * 30 = 60 mm
- Addendum (ha) = m = 2 mm
- Dedendum (hf) = 1.25 * m = 1.25 * 2 = 2.5 mm
- Whole Depth (h) = 2.25 * m = 2.25 * 2 = 4.5 mm
- Outside Diameter (da) = m * (z + 2) = 2 * (30 + 2) = 2 * 32 = 64 mm
- Root Diameter (df) = m * (z – 2.5) = 2 * (30 – 2.5) = 2 * 27.5 = 55 mm
- Circular Pitch (P) = π * m = π * 2 ≈ 6.283 mm
- Tooth Thickness (s) = P / 2 = (π * m) / 2 ≈ 3.142 mm
- Space Width (e) = P / 2 = (π * m) / 2 ≈ 3.142 mm
These calculated values provide the essential geometric data needed for manufacturing and integrating the spur gear into a mechanical system.