Fastener Hole

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

Audit 0.4.1 · source sha 24034f36bad7 · 19 Oct 2026Report an issue or request a re-scan

• Publisherghbalf GitHub userOwner of the repository this skill is read from
• Source folderghbalf/freecad-ai/skills/fastener-holeThe exact folder we audited
• LicenceLGPL-2.1As the repository states it
• Commit pinned for this verdict24034f36bad7A new audit runs when the source changes
• Repository statusNot archivedLast push 2 days ago
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Create standard fastener holes: clearance, counterbore, or countersink.

---
name: fastener-hole
description: "Create standard fastener holes: clearance, counterbore, or countersink."
---

# Fastener Hole Patterns

Create standard fastener holes: clearance, counterbore, or countersink.

## Hole types

### Clearance holes (through-hole for bolt to pass through)
| Size | Close fit | Normal fit |
|------|-----------|------------|
| M2   | 2.2mm     | 2.4mm      |
| M2.5 | 2.7mm     | 2.9mm      |
| M3   | 3.2mm     | 3.4mm      |
| M4   | 4.3mm     | 4.5mm      |
| M5   | 5.3mm     | 5.5mm      |
| M6   | 6.4mm     | 6.6mm      |
| M8   | 8.4mm     | 9.0mm      |

### Counterbore (socket head cap screw)
| Size | CB diameter | CB depth |
|------|-------------|----------|
| M3   | 6.5mm       | 3.0mm    |
| M4   | 8.0mm       | 4.0mm    |
| M5   | 10.0mm      | 5.0mm    |
| M6   | 11.5mm      | 6.0mm    |
| M8   | 15.0mm      | 8.0mm    |

### Countersink (flat head screw, 90 degree)
| Size | CS diameter |
|------|-------------|
| M3   | 6.3mm       |
| M4   | 8.4mm       |
| M5   | 10.4mm      |
| M6   | 12.6mm      |

## Parameters to ask (if not provided)
- **Screw size**: M2 through M8
- **Hole type**: clearance / counterbore / countersink
- **Fit**: close / normal (for clearance holes)
- **Target object**: body or feature to cut into
- **Positions**: list of XY coordinates, or pattern (linear/circular)
- **Pattern**: if applicable — count, spacing, or bolt circle diameter + count

## Construction
1. Create a sketch on the specified face
2. For each hole position, add a circle (clearance diameter)
3. Pocket through-all for the clearance hole
4. For counterbore: add a second larger circle, pocket to CB depth
5. For countersink: use a cone (Part.makeCone) to create the 90-degree chamfer

## Cleanup
After construction, hide all sketches for a clean viewport:
```python
for obj in App.ActiveDocument.Objects:
    if obj.TypeId == "Sketcher::SketchObject":
        obj.Visibility = False
```

Excerpt, first 1,944 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/ghbalf/freecad-ai
git -C freecad-ai checkout 24034f36bad7

Works in

1. 2026-10-19
   ✓SAFE B 89 / 100

   first audit · source 24034f36bad7

Questions about Fastener Hole

• github.com/ghbalf/freecad-ai/tree/master/skills/fastener-hole — the audited source at commit 24034f36bad7 and every finding aboveObserved · 19 Oct 2026

Spotted something wrong? Report a correction · Methodology