# Geometry for Cuts, Clearance, and Fit

Use simple geometry to reason about square corners, clearances, hole spacing, diagonal checks, and parts that need to fit before cutting material.

## Outcome
Check a physical layout with diagonals, offsets, spacing, and clearance before making a permanent cut.

## Safe first step
Sketch the part and mark fixed edges, clearance zones, and measurement points before measuring diagonals.

## Ladder steps
### 1. Mark the fixed references
A layout needs one edge, hole, or corner that everything else references.

Check: The drawing shows which feature is fixed.

### 2. Check square with diagonals
Equal diagonals can prove a rectangle is square enough for many builds.

Check: The two diagonal measurements are close within the chosen tolerance.

### 3. Add clearance zones
A part that fits on paper can still collide with fasteners, wires, or movement.

Check: The sketch marks the areas that must stay empty.

### 4. Measure before cutting
Permanent work should wait until the layout has a check.

Check: The note lists the final check before cutting, drilling, or printing.

## Examples
### Estimate a rectangle diagonal
```sh
diagonal = sqrt(width^2 + height^2)
```
Expected signal: The expected diagonal for a square-check comparison

### Check fit before cutting or printing
```sh
clearance = opening - part_size
```
Expected signal: A positive clearance value with units

### Find the centerline of a part
```sh
center = length / 2
```
Expected signal: A reference point for symmetric layout

## Common traps
- Measuring from a rough edge without naming it.
- Forgetting tool kerf or drill clearance.
- Using exact math on flexible or rough material without tolerance.

## Practice task
Draw a rectangular panel with two holes. Mark the reference edge, centerline, hole spacing, clearance, and diagonal check.

## Next steps
- Use scale and unit conversions for material estimates.
- Use CAD constraints for editable sketches.
- Use fabrication lessons before permanent work.

## Related
- [CAD constraints first sketch](/learn/cad-constraints-first-sketch/)
- [Fabrication and materials](/topics/fabrication/)
- [Maker Math](/topics/math/)
- [Project paths](/projects/)

## Obsidian backlinks

Use these wiki links to connect this note inside a local maker vault:

- [[TopicLadder]]
- [[Maker Learning]]
- [[Geometry for Cuts Clearance and Fit]]
- [[Maker Math]]
- [[math]]
- [[layout]]
- [[Mark the fixed references]]
- [[Check square with diagonals]]
- [[Add clearance zones]]
- [[Measure before cutting]]
- [[CAD constraints first sketch]]
- [[Fabrication and materials]]

## Source and next routes

Source: https://topicladder.com/learn/geometry-for-cuts-clearance-and-fit/

- [CAD constraints first sketch](/learn/cad-constraints-first-sketch/)
- [Fabrication and materials](/topics/fabrication/)
- [Maker Math](/topics/math/)
- [Project paths](/projects/)