Machining fixture clamp-force estimate calculator

Frictional holding at supplied clamp force; cutting direction parallel to contact.

cnc-clamping.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

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

Scenario	holdingN	factor
	200	2
	200	2.5

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.

holding factor target2.00 ✓ passes

BASELINE INPUTS

cuttingForce100 Nfriction0.2 clampForce1000 N

CALCULATED

holding200 N

factor2

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Machining fixture clamp-force estimate
# Scope: Frictional holding at supplied clamp force; cutting direction parallel to contact.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

cuttingForce = 100 N
friction = 0.2
clampForce = 1000 N

holding := friction*clampForce [N]
factor := holding/cuttingForce

check holding factor target: factor >= 1.5

scenario alternative: cuttingForce = 80 N

Calculated from your source · not saved

Baseline · Baseline

holding factor target2.00 ✓ passes

alternative · alternative

holding factor target2.50 ✓ 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.

holding: holding = friction*clampForce [N]
factor: factor = holding/cuttingForce

Original worked example

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

Given

cutting force: 100 N
friction: 0.2
clamp force: 1000 N

Calculated

holding: 200 N
factor: 2

Assumptions and limits

Frictional holding at supplied clamp force; cutting direction parallel to contact.

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: Machining fixture clamp-force estimate. Inputs: cutting forces; friction; locator and clamp geometry. Outputs: required clamp forces; load path. Model scope: Tool, stock and machine-specific cutting 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: cutting forces, friction, locator and clamp geometry
Outputs: required clamp forces, load path
Modes: calculate, compare, sweep
Drawing: Tool engagement and material-removal preview

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