Printed-part mating clearance calculator

Nominal mating gap minus worst-case two-surface print errors.

3d-printing-clearance.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	minimumGapmm
	0.2
	-1.88

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

positive fit gap0.20 mm✓ passes

BASELINE INPUTS

hole10.4 mmshaft10 mmholeError0.1 mmshaftError0.1 mm

CALCULATED

minimumGap0.2 mm

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Printed-part mating clearance
# Scope: Nominal mating gap minus worst-case two-surface print errors.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

hole = 10.4 mm
shaft = 10 mm
holeError = 0.1 mm
shaftError = 0.1 mm

minimumGap := hole-shaft-holeError-shaftError [mm]

check positive fit gap: minimumGap >= 0.1 mm

scenario alternative: hole = 8.32 mm

Calculated from your source · not saved

Baseline · Baseline

positive fit gap0.20 mm ✓ passes

alternative · alternative

positive fit gap-1.88 mm × fails

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

minimum gap: minimumGap = hole-shaft-holeError-shaftError [mm]

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

hole: 10.4 mm
shaft: 10 mm
hole error: 0.1 mm
shaft error: 0.1 mm

Calculated

minimum gap: 0.2 mm

Assumptions and limits

Nominal mating gap minus worst-case two-surface print errors.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Printed-part mating clearance. Inputs: feature tolerances; process bias; desired fit. Outputs: gap interval; candidate nominal clearance. Model scope: Geometry plus explicitly calibrated machine and material parameters. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: feature tolerances, process bias, desired fit
Outputs: gap interval, candidate nominal clearance
Modes: calculate, compare, sweep
Drawing: Part, orientation and layer preview

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS