CALCULATORS / WIRES, CABLES AND HARNESSES

Wire-bundle fit through a bore calculator

Area-based circular bundle envelope at supplied packing fraction; no exact circle packing.

wires-bundle-fit.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

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

Scenario	areamm^2	bundleDiametermm
	44.8799	7.55929
	35.9039	6.76123

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.

bundle diameter budget7.56 mm✓ passes

BASELINE INPUTS

count10 wireDiameter2 mmpacking0.7

CALCULATED

area44.88 mm^2

bundleDiameter7.5593 mm

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Wire-bundle fit through a bore
# Scope: Area-based circular bundle envelope at supplied packing fraction; no exact circle packing.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

count = 10
wireDiameter = 2 mm
packing = 0.7

area := count*pi*wireDiameter^2/(4*packing) [mm^2]
bundleDiameter := sqrt(4*area/pi) [mm]

check bundle diameter budget: bundleDiameter <= 10 mm

scenario alternative: count = 8

Calculated from your source · not saved

Baseline · Baseline

bundle diameter budget7.56 mm ✓ passes

alternative · alternative

bundle diameter budget6.76 mm ✓ passes

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.

area: area = count*pi*wireDiameter^2/(4*packing) [mm^2]
bundle diameter: bundleDiameter = sqrt(4*area/pi) [mm]

Original worked example

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

Given

count: 10
wire diameter: 2 mm
packing: 0.7

Calculated

area: 44.8799 mm^2
bundle diameter: 7.55929 mm

Assumptions and limits

Area-based circular bundle envelope at supplied packing fraction; no exact circle packing.

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: Wire-bundle fit through a bore. Inputs: wire outer diameters; arrangement; bore; bend and assembly margins. Outputs: packing feasibility; nominal radial clearance. Model scope: Conductor geometry and sourced installation/component limits. 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: wire outer diameters, arrangement, bore, bend and assembly margins
Outputs: packing feasibility, nominal radial clearance
Modes: calculate, compare, sweep
Drawing: Harness and voltage-drop diagram

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