Drawing Converter MCP Server
Convert technical drawings (PDF) and engineering callouts between metric and imperial — from any MCP-enabled AI assistant.
This Model Context Protocol server exposes the conversion engine behind metric-to-imperial-converter.imnoo.com (by Imnoo): shop-floor-precision unit conversion for dimensions, ± tolerances, ISO fit classes, threads, surface roughness and weights — including producing a converted copy of a drawing PDF with every value stamped in place.
"Convert bracket.pdf to imperial and tell me what replaces the M8 thread"
│
▼ (your AI assistant calls the tools)
extract_drawing_text ──► classify values ──► convert_drawing_pdf
│
▼
bracket.imperial.pdf ✓ Ø30 H7 → Ø1.1811 H7
✓ M8 → 5/16-18 UNC
| Tool | What it does |
|---|
convert_value | One value, engineering-grade rounding: length (mm⇄in), tolerance deviation, GD&T value, surface roughness (Ra µm⇄µin), weight (kg⇄lb), thread designation. Returns exact + display values, derivation method and confidence. |
convert_text | A printed callout string, notation preserved: Ø30 H7 → Ø1.1811 H7, 84±0.1 → 3.3071±0.0039, M8 → 5/16-18 UNC, 1/4-20 UNC → M6. Angles stay untouched. |
lookup_thread | ISO metric ⇄ Unified (UNC) cross-reference: major diameters, pitch/TPI, nearest-standard matching. Omit the designation for the full M2–M30 chart. |
extract_drawing_text | Reads a drawing PDF's text layer: indexed tokens with positions/rotation, page geometry, and a heuristic guess of the drawing's unit system. |
convert_drawing_pdf | Writes a converted copy of the PDF with every recognised value stamped over the original callout (size and rotation matched). The source file is never modified. |
Plus a convert-drawing prompt that walks the assistant through extract → classify → convert.
The AI-analysis step stays with your assistant. extract_drawing_text hands the model every printed token with its position; the model decides which tokens are real values (and whether a bare 3.2 is a length or an Ra roughness) and passes that as classifications to convert_drawing_pdf. No API keys, no cloud calls — the server itself is fully deterministic and offline.
Installation
Requires Node.js ≥ 18.
Claude Code
claude mcp add drawing-converter -- npx -y drawing-converter-mcp
Claude Desktop
Add to claude_desktop_config.json (Settings → Developer → Edit Config):
{
"mcpServers": {
"drawing-converter": {
"command": "npx",
"args": ["-y", "drawing-converter-mcp"]
}
}
}
Cursor
Add to Cursor — or add to ~/.cursor/mcp.json:
{
"mcpServers": {
"drawing-converter": {
"command": "npx",
"args": ["-y", "drawing-converter-mcp"]
}
}
}
VS Code (GitHub Copilot)
code --add-mcp '{"name":"drawing-converter","command":"npx","args":["-y","drawing-converter-mcp"]}'
Windsurf / other stdio clients
Any client that launches stdio servers works with:
npx -y drawing-converter-mcp
Example session
You: Convert C:\drawings\flange.pdf to imperial.
Assistant: calls extract_drawing_text — 63 tokens, source system: metric (high confidence — "mm", ISO 2768). classifies tokens, skips the title block, marks 1.6 next to the surface symbol as roughness, calls convert_drawing_pdf — wrote C:\drawings\flange.imperial.pdf, 17 values converted: Ø40 H7 → Ø1.5748 H7, 2× M6 → 1/4-20 UNC (nearest standard — not interchangeable), Ra 1.6 → Ra 63 µin…
Quick one-liners work too: "what's 84±0.1 mm in inches?" → convert_text → 3.3071±0.0039.
Precision rules
Conversions follow the same rules as the web app:
- Exact factors by international definition (25.4 mm/in, 0.45359237 kg/lb — NIST/ISO 80000).
- Display rounding mirrors shop-floor convention: a 0.01 mm step maps to 4-decimal inches; tolerance deviations keep an extra significant digit.
- Threads are resolved against an ISO-metric ⇄ UNC chart (M2–M30), tagged
table for charted rows or nearest when snapped by major diameter. Metric and inch threads are never interchangeable — the tools say so on every thread conversion.
- Every converted value reports how it was derived (
exact / rounded / table / nearest) and a confidence score.
Limitations
- The PDF must have a text layer. Scanned or flattened CAD exports have none — the web app handles those with in-browser OCR + AI analysis.
- One page is converted per call (
page parameter, default 1); other pages pass through unchanged.
- Fractional-inch callouts (
1 3/4) aren't converted yet — decimal-inch drawings work fine.
- Converted values are stamped over the original callouts. Always verify safety-critical dimensions before manufacturing use.
Development
This package is built from the Drawing Converter monorepo at Imnoo, where it imports the web app's conversion engine directly — so the web app and this server convert identically by construction. Every release is gated on 31 end-to-end checks that drive all five tools over stdio against a generated sample drawing.
Issues and feature requests are welcome in this repository.
About Imnoo
Imnoo is the AI-powered planning, scheduling and
quoting platform for CNC manufacturers — trusted by over 3,000 shops.
One system for the whole job, not just the spindle time:
- Planning — automatic manufacturing plans, machine recommendation, raw
material, catalog and purchase-part sourcing, subcontracting. Beyond milling
and turning: deep hole drilling, sheet metal, casting, profile parts.
- Quoting — AI cost and cycle-time estimation for milling, turning and EDM
from a 2D PDF alone; feature-by-feature costing; market-price benchmarking;
hourly-rate calculation; a 24/7 instant-quoting webshop.
- Drawing intelligence — automatic tolerance extraction, 2D-to-3D matching,
axis and orientation detection, generated quality-check protocols.
- CAM — AI tool recommendation, automatic toolpath and G-code generation,
and connected machines feeding real production data back into every quote.
- Libraries and insights — your own tool and material libraries, plus a
searchable database of every part you've ever quoted.
- IP protection — physically separated tenants, automatic drawing masking,
Swiss hosting, end-to-end encryption.
Quote the complete job — not just the spindle time.
Book a demo at imnoo.com
License
MIT © Imnoo AG