CALCULATORS / MOLDING, CASTING AND TOOLING

Molded wall and rib proportion screening calculator

Rib thickness ratio using supplied nominal wall and rib dimensions; no sink prediction.

molding-wall-rib.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

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

Scenario	ratio
	0.6
	0.75

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.

example rib ratio budget0.60 ✓ passes

BASELINE INPUTS

wall2 mmrib1.2 mm

CALCULATED

ratio0.6

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Molded wall and rib proportion screening
# Scope: Rib thickness ratio using supplied nominal wall and rib dimensions; no sink prediction.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

wall = 2 mm
rib = 1.2 mm

ratio := rib/wall

check example rib ratio budget: ratio <= 0.6

scenario alternative: wall = 1.6 mm

Calculated from your source · not saved

Baseline · Baseline

example rib ratio budget0.60 ✓ passes

alternative · alternative

example rib ratio budget0.75 × 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.

ratio: ratio = rib/wall

Original worked example

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

Given

wall: 2 mm
rib: 1.2 mm

Calculated

ratio: 0.6

Assumptions and limits

Rib thickness ratio using supplied nominal wall and rib dimensions; no sink prediction.

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: Molded wall and rib proportion screening. Inputs: wall dimensions; rib geometry; material/process criteria. Outputs: ratio checks; sink-risk indicators. Model scope: Early process estimates with material and supplier data. 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: wall dimensions, rib geometry, material/process criteria
Outputs: ratio checks, sink-risk indicators
Modes: calculate, compare, sweep
Drawing: Part, cavity and runner diagram

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