Flame jet drill
The Flame Jet Drill is a type of drilling equipment whereby there is no contact with the drilling surface, therefore the drill never wears down.
- freepatentsonline.com - Flame Jet Drill Patent
- Flame Jet Drilling and Chambering to Great Depths in Crystalline Rock
- US Patent 4066137
- Journal of Mining Science
- "National Geographic Channel Australia and New Zealand - Megastructures". 080712 natgeotv.com.au List of National Geographic MegaStructures series.