Slip Fit Diameter Guide
Why Slip Fit Matters
A slip fit lets one cylindrical part slide into another with controlled clearance. It is common in pins, bushings, gauges, pulleys, and serviceable assemblies. The goal is simple. The hole must stay larger than the shaft under normal conditions. Yet the gap must not become so large that alignment, vibration, or wear becomes unacceptable.
Key Inputs
This calculator uses a nominal diameter, hole deviations, shaft deviations, and optional thermal data. Lower and upper deviations describe the smallest and largest permitted part size. They may come from a drawing, shop standard, gauge report, or design note. Enter positive values when a limit is above nominal. Enter negative values when it is below nominal.
Clearance Meaning
Minimum clearance is the tightest possible gap. It uses the smallest hole and largest shaft. Maximum clearance is the loosest possible gap. It uses the largest hole and smallest shaft. Mean clearance gives a practical center value. Clearance spread shows total variation caused by both part tolerances.
Thermal Review
Temperature can change slip behavior. A warmer hole expands. A warmer shaft also expands. When the shaft grows more than the hole, clearance drops. When the hole grows more, clearance rises. The thermal section estimates this change from expansion coefficient and temperature difference. It is useful for pressroom, engine, mold, and outdoor equipment checks.
Design Notes
A good slip fit is not only a number. Surface finish, roundness, coating, plating, burrs, lubrication, and measuring method matter. Very small clearance may feel smooth in clean test parts, but it can bind after coating or dirt. Very large clearance may assemble easily, yet reduce concentricity. Use this tool for planning, review, and comparison. Final production limits should follow your drawing, standard, and inspection method.
Practical Workflow
Start with the nominal size. Add known hole and shaft deviations. Check minimum clearance first. If it is negative, the fit may jam or become a transition fit. Check maximum clearance next. If it is excessive, tighten one tolerance band or change the target clearance. Export the table for records, purchase notes, or quality review. Save each run with units and assumptions, so later audits can trace every tolerance choice without repeating manual calculations again.