Tools and Techniques Used to Carve Mount Rushmore

Mount Rushmore (1927-1941) was carved using a combination of industrial blasting, pneumatic tools, and hand-finishing—removing ~450,000 tons of granite.

Primary Methods

1. Blasting (90% of material removal)

• Dynamite: 60% straight, 40% gelatin—placed in drilled holes
• Blasting caps: Electric detonators for precise timing
• Jackhammers (pneumatic drills): Ingersoll-Rand, Gardner-Denver models—drilled 3-4 m deep holes
• Powdermen: Specialized crew calculating charges for "honeycombing" (closely spaced holes)

2. Drilling & Pneumatic Tools

• Air compressors: 3 Ingersoll-Rand 1,050 cfm compressors (steam → electric)
• Pneumatic drills: Lighter "drifters" for detail work (25-45 lb)
• Steam drills: Early phase only (replaced by pneumatic)

3. Hand Finishing (Final 3-6 inches)

• Chisels: 1/2" to 2" widths, carbide-tipped (later)
• Points & claws: For texturing, hair, eyes
• Bush hammers: Pneumatic multi-point for skin texture
• Rasps, scrapers, sandpaper: Final smoothing

4. Surveying & Measurement

• Pointing machine: Borglum's custom 3D pantograph (1:12 scale model → mountain)
• Theodolites: Precise angle measurement for feature placement
• Plumb bobs, levels, tapes: Daily verification
• Red paint marks: Guided drillers on hole placement

5. Support Infrastructure

• Cableways/Aerial tram: Moved workers, tools, dynamite up mountain
• Stairways/Ladders: 506 steps to summit + bosun's chairs
• Scaffolding: Suspended platforms for high work
• Blacksmith shop: On-site tool sharpening, repair
• Compressor house: Powered all pneumatic tools

Workforce & Safety

• 400 workers total (miners, drillers, carvers, laborers)
• 0 fatalities during carving (remarkable for era)
• Silicosis risk: Dust mitigation (water spray, limited exposure)
• Seasonal: May-October only (weather)

Borglum's Innovation

Gutzon Borglum adapted pointing machine technology (used for statue replication) to monumental scale, enabling precise transfer from 1:12 plaster models to 60-foot faces.

The project remains a landmark achievement in large-scale precision stone removal using 1920s-30s technology.