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Fit Master v3.8

ISO 286 tolerance and interference calculator

1. ISO 286 comprehensive boundaries (0.01 to 3150 mm)

Fit auto-suggestion helper
Dimensional parameters & manual adjustments
Minimum hole size
0.0000 mm
Maximum hole size
0.0000 mm
Minimum shaft size
0.0000 mm
Maximum shaft size
0.0000 mm

2. Thermal elastic properties & lengths

Hole (hub companion) material properties
Shaft structural core material properties

3. Temperature Value Probe

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4. Production Condition Summary

Fit bounds (minimum / maximum)
0.0 / 0.0 μm
Maximum interface pressure
0.0 MPa
Torque holding capacity (minimum / maximum)
0.0 / 0.0 N·m
Axial stripping force (minimum / maximum)
0.00 / 0.00 kN

5. Plots (-50°C to 500°C)

Legal & liability disclaimer:
This software utility is provided solely for educational, research, and academic reference purposes. It is explicitly not intended to serve as a substitute for certified commercial engineering calculations, manufacturing blueprints, or safety-critical interference fit machinery designs. This utility uses mathematical models based on standard ISO 286 specifications and thick-walled elastic cylinder formulations (Lamé's mechanics) to simulate contact constraints. All mechanical assembly setups must be independently vetted and approved by a licensed professional mechanical engineer in compliance with governing regulatory frameworks. The author and publishers decline all responsibility or liability for structural failures, component galling, or legal ramifications emerging from software application.
Author note:
Fit Master Engine was developed by Wouter van Zoggel.
Explainer for verification purposes:
To validate or replicate these engine outcomes independently, the following steps are applied by this tool:
  • For given geometry configurations, standard boundaries are processed according to ISO 286 mappings to find baseline deviations (\(EI, ES, ei, es\)) across standard international tolerance classes (\(IT\)).
  • The dimensional change under transient temperatures is evaluated by tracking dimensional scaling variables relative to the manufacturing baseline (\(T_{mfg} = 20^\circ\text{C}\)): \[ \delta_T = \delta_{mfg} + d \cdot \left( \alpha_{hole} \cdot \Delta T_{hole} - \alpha_{shaft} \cdot \Delta T_{shaft} \right) \]
  • Interface contact pressure (\(p\)) inside active interference thresholds is extracted by applying compatibility conditions across joint interactions using Lamé's thick cylinder elastic constraints: \[ p = \frac{-\delta_T}{d \cdot \left( \frac{C_{hub}}{E_{hub}} + \frac{C_{shaft}}{E_{shaft}} \right) } \]
  • Where the structural rigidity constants (\(C_{hub}, C_{shaft}\)) define cross-sectional geometry ratios mapping outer hub boundaries (\(d_{hub}\)) and internal hollow shaft dimensions (\(d_{shaft\_hole}\)) against Poisson values (\(\nu\)): \[ C_{hub} = \frac{d_{hub}^2 + d^2}{d_{hub}^2 - d^2} + \nu_{hole}\] \[ C_{shaft} = \frac{d^2 + d_{shaft\_hole}^2} {d^2 - d_{shaft\_hole}^2} - \nu_{shaft}\]
  • Frictional holding limits are calculated assuming uniform pressure conditions across the effective joint interaction length (\(L\)) and global friction factor (\(\mu\)): \[ F_{axial} = p \cdot \pi \cdot d \cdot L \cdot \mu\] \[ T_{torque} = F_{axial} \cdot \frac{d}{2}\]