How to 3D Scan a Part: A Practical Guide

Why 3D Scan a Part?

3D scanning captures the exact geometry of a physical object as a digital 3D model. This is invaluable for:

• Reverse engineering — Recreating a part when no CAD file or drawing exists
• Quality inspection — Comparing a manufactured part to the original design
• Digital archiving — Preserving the geometry of legacy or obsolete parts
• Modification — Scanning an existing part to design something that fits around it (adapters, brackets, enclosures)

In automotive work, 3D scanning is particularly useful for transmission adapters, engine bay measurements, and custom bracket design where you need precise dimensions of existing components. For complex parts like gears and shafts, see our guide to reverse engineering with 3D scanning.

Types of 3D Scanners

Structured Light Scanners

These project a pattern of light onto the part and use cameras to capture how the pattern deforms. They offer high accuracy (down to 0.05mm) and are excellent for small to medium parts. Examples include EinScan, Revopoint, and Shining3D scanners.

Best for: Small to medium parts, high-detail work, workshop use

Laser Scanners

Laser line scanners sweep a laser across the surface and triangulate the position of each point. They handle shiny and dark surfaces better than structured light. HandySCAN and MetraSCAN are popular options.

Best for: Shiny or dark parts, larger assemblies, industrial applications

Photogrammetry

Uses photographs taken from many angles to reconstruct 3D geometry using software. Lower cost of entry but generally less accurate. Tools like Meshroom or RealityCapture can produce good results.

Best for: Large objects, organic shapes, budget scanning

LiDAR (Phone-Based)

Modern phones with LiDAR sensors (iPhone Pro, iPad Pro) can capture rough 3D scans. Accuracy is limited (±5-10mm) but useful for large-scale reference measurements.

Best for: Quick reference scans, room/space measurements, initial feasibility checks

Preparing the Part

Good preparation is the difference between a clean scan and hours of cleanup.

1. Clean the part — Remove oil, grease, dust, and loose debris. Scanning captures everything on the surface.

1. Apply scanning spray (if needed) — Shiny, reflective, or dark surfaces don't scan well. A thin coat of scanning spray (e.g., AESUB Blue) creates a temporary matte surface that evaporates after a few hours. Alternatively, developer spray or dry powder works in a pinch.

1. Place reference targets — Stick small adhesive reference markers on or around the part. These help the scanner track its position and align scan passes. Space them 50-100mm apart, avoid placing them in straight lines.

1. Stabilise the part — Mount it securely so it doesn't move during scanning. Use a turntable for small parts or clamps/fixtures for larger ones.

Scanning Technique

Small Parts (fits on a table)

• Use a turntable and let the scanner capture a full rotation
• Do multiple passes at different angles to capture undercuts and hidden faces
• Overlap each pass by at least 30% for clean alignment

Medium Parts (engine, gearbox, etc.)

• Walk around the part with a handheld scanner
• Start from one end and work systematically to the other
• Maintain a consistent distance from the surface (usually 200-400mm depending on scanner)
• Don't rush — slow, steady passes produce cleaner data
• For examples of professional gearbox scan output, see our BMW ZF 8HP45 gearbox scan or Nissan RB26 engine scan

Large Parts (engine bay, vehicle interior)

• Scan in sections and align them together in software
• Use plenty of reference targets
• Consider using a combination of scanning and manual measurements for very large areas

Post-Processing

Raw scan data needs cleanup before it's useful:

1. Alignment — If you captured multiple scan passes, align them in the scanner's software (usually automatic with reference targets).

1. Mesh cleanup — Remove noise, fill small holes, smooth rough areas. Tools like Geomagic Wrap, MeshLab (free), or CloudCompare (free) work well.

1. Hole filling — Areas the scanner couldn't see (deep pockets, undercuts) will have gaps. Fill them manually or use automatic hole-filling tools.

1. Export — Export as STL or OBJ for 3D printing, or convert to STEP/IGES for CAD work (see our guide on converting scans to STEP files).

Tips for Better Scans

• Scan in a stable environment — vibrations and temperature changes affect accuracy
• Avoid direct sunlight — it interferes with structured light and laser scanners
• Calibrate your scanner before each session
• Capture more data than you think you need — it's easier to remove excess than to re-scan
• Save your raw scan data separately before doing any cleanup

What We Offer

At JDL Innovations, we provide professional 3D scanning services using high-accuracy structured light scanners. We also sell ready-to-use 3D scans of automotive components in our online store — including ZF gearbox scans, engine scans, transfer case scans, and complete vehicle body scans. If you need a part scanned, get in touch.