The starting question
What must this joint do, and which information supports the proposed fit?
Interactive example / Hands-on design
A tiny difference.
A completely different fit.
Drag the steel shaft into the housing. Change its diameter and try again.
Drag horizontally with a mouse or touch. Keyboard: focus the shaft and use ← / →, or use the slider below.
Choose the nominal size
Nominal geometry demonstration, not a fit specification or force simulation. The tiny diameter differences are exaggerated in the picture. Real assembly also depends on size limits, alignment, surface finish, temperature and material.
For your own project
Which part do you need help with?
Start with what you know. Keep the undecided details open for discussion.
You bring
The parts, photos or measurements you already have.
We can help explore
How the pieces connect, move and leave room for access.
Discuss next
Which interfaces must stay fixed, and what can change?
Read the dimensional range first
Our fit explainer subtracts shaft diameter from hole diameter. A negative result means dimensional interference; it is not a negative force. The calculation compares entered size limits only.
For an invented hole range of 20.000–20.010 mm and shaft range of 20.020–20.030 mm, diametral clearance runs from −0.030 to −0.010 mm. Equivalently, diametral interference is 0.010–0.030 mm. These limits are an arithmetic example, not a recommended fit.
Describe function and operating conditions
Record what the joint locates or retains, the expected loads, motion, temperatures and required assembly or removal method. Identify the actual materials and geometry, including whether the shaft is hollow and how much material surrounds the bore. Keep unknowns visible.
For rolling bearings specifically, NTN identifies load, operating temperature, bearing type and shaft or housing material as fit-selection factors. NTN also warns that excessive press fit can remove bearing internal clearance and contribute to early failure. That bearing guidance is not a universal sizing rule for every shaft joint.
Keep force and temperature predictions separate
The inherited TPM press-fit model estimates contact pressure, holding force, torque, stress and heating using elastic properties, friction and geometric assumptions. Its source notes flag some property assumptions as unverified. We have not independently validated that model or imported its presets or safety thresholds.
A dimensional overlap alone does not establish press capacity, retention, stress margin or a safe heating temperature. Ask the responsible designer or component supplier to review the application and approved assembly procedure. Record the source and revision of any selected limits before making a purchase or assembly decision.
Bring this to the review
Your working checklist
Use these prompts to record open questions. Checking a box does not approve a design or manufacturing process. Selections last for this page visit.
References & further reading
References support the named topic; they do not certify a design, setup or product.
Planning guidance and illustrative examples. Confirm project-specific requirements with the responsible design, manufacturing and quality teams.
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