Tom Ross writes:
"With a common size sarcophagus requiring over 55 thousand inches of drilling. With one crew drilling it would take 25 years at 7 days a week 24 hours a day."

The article below is in response to a theory put forth about Egyptian drilling techniques in the video above.

Egyptian Drilling

by Tom Ross
Superintendent, Construction and Refractory Engineering
(All One World Egypt Tours Traveler - Jan 2008 & Nov 2010)

Copper mines were not found in Egypt till around Djoser's time. In the 3-4 dynasties it is believed that the Egyptians mined about 4 tons (8000 pounds) per year.

Egyptian drill bits found ranged in size from .25 inches to 5 inches diameter.  They ranged in thickness up to 1/5 of an inch. Thus a 2” hole drill with 1/5” wall thickness 4’ long would weigh over 6 pounds. So in the time period of the 3-4 dynasties they could produce over 1300 of these bits per year. If that was all they made with the copper, which we know it not accurate.

A common size sarcophagus had a portion hollowed out 4’ wide 8’ long and 4’ deep. Approximately removing 221,184 cubic inches of material. I would think a 2’ diameter drill would be the size of choice.

For me to drill granite I would use water assisted electric core drill with a diamond cutting head.  [See this at NEWS page, Jan 17th - video of drilling in the Red Pyramid]

On average we can cut 1’ in depth with 3000 revolutions of the drill (with mild pressure applied to the bit) twenty 4’ deep holes is a common life for a bit used in this fashion. A hand operated core drill could be rotated at possibly 60 revolutions per min. The cutting ability is affected by the cutting agent. Dune sand is a poor choice. Dune sand had rounded edges caused by the way it is created. I would say it had less than 20% of the cutting abilities of diamonds. Thus the 3000 revolutions would increase to 15,000 revolutions per inch equaling 4+ hours per inch of Egyptian style drilling. With a common size sarcophagus requiring over 55 thousand inches of drilling. With one crew drilling it would take 25 years at 7 days a week 24 hours a day.

While drilling the drill casing is wearing out due to the cutting agent rubbing between the hole and the side of the drill. Modern core drills address this with water. The water lubricates the bit and flushes out the material between the casing and the side of the hole. My thoughts are that the copper drills used would wear out at about a 15% ratio of the holes drilled. Meaning you will need 8250 inches of drill to drill out 55,000 inches of hole. This translates to 4,200 pounds of copper. A six month supply of all Egypt’s copper to drill out one Sarcophagus. 

For me to drill out a sarcophagus I would use a four drill crew. This would take me 6 months. The correct way to remove the granite is to drill holes at the corners and saw cut out the middle. This could be done in several weeks. That is what I believe was really done. Saw marked are found in several locations in Egypt, even on Khufu’s sarcophagi. These were noted by Sir William Petrie over one hundred years ago.

All in all I do not believe in ancient time precious materials and manpower would have been so utilized for one minor project as holing out a piece of granite. That or they were able to achieve this feat with a lot less effort than the common beliefs of Egyptian stone working would dictate!

Information obtained from Advanced Machining in Ancient Egypt by Christopher P. Dunn.

And from http://www.theglobaleducationproject.org/egypt/articles/hrdfact1.php

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