An inside look at carving a mountain
The highly complex steps in the mountain carving process at Crazy Horse can be summed up in relatively simple terms.
We are making a very large duplicate of Korczak's sculpture to tell the story of North American Indian cultures.
That artwork depicts the Lakota warrior, Crazy Horse, seated on his horse and pointing over the horse's head as he
says, "My lands are where my dead lie buried." In order to convey that powerful story on a monumental scale on
the mountain we follow three basic steps: 1) measure Korczak's model; 2) measure the mountain; 3) remove all the
rock that doesn't fit! In reality each of these steps gets quite complex and requires the use of powerful tools
and techniques, but the guiding principles remain quite simple.
The members of the Crazy Horse mountain crew are experts in precision blasting, equipment operation and engineering.
They maintain a strong emphasis on safety in all steps of the operation and are proud to have an outstanding safety
record. Here's a little closer look at each of the meticulously detailed steps this team carries out to carve the
mountain:
Measure Korczak's model
Measuring systems have evolved steadily during the 60-year history of the mountain carving. Korczak relied
on artistic estimates and his incredibly practiced eye and natural feel for dimensions and scale. After his
death, his family and the mountain crew developed a mechanical pointing system to measure the 1/34th scale model
of Crazy Horse's face. After completion of the face, we designed and built another mechanical pointing system
to measure the 1/300th scale model of the entire carving. More recently laser scanning methods have been used
to measure the 1/34th scale model and just in the past year brand new technology has been used to measure the
1/300th scale model with a laser scanning arm. Monique Ziolkowski is currently working to build a 1/60th
scale model that will combine the artistic elements of Korczak's story with dimensions and geologic details
from the mountain. Some combination of mechanical pointing systems and laser scanning technology will likely
be used to measure this model when it is complete.
Measure the mountain
Korczak used a combination of his artistic eye, tape measures and a beautiful old theodolite (survey instrument)
to determine the basic location of his model within the mountain and begin the process of removing excess rock.
A 60-foot long measuring boom was fixed to the top of Crazy Horse's head in 1987 to direct the work on the face.
A plumb bob suspended from that measuring boom was used to transfer numbers from the pointing system on the
1/34th model of Crazy Horse's face.
When work moved beyond the face in 1998, a survey control system was
developed and a modern survey instrument was used to measure the entire mountain. This instrument, known
as a total station, measures very precise angles and distances from known control points to calculate 3
dimensional coordinates for any point on the mountain. It uses an infrared beam reflected from a hand held prism
to measure distances up to several thousand feet with accuracy to the nearest 1/1000th of a foot. Measurements
from Korczak's models are transferred to the mountain using this same instrument and survey control system.
Laser scanning equipment has been used to measure the entire mountain on several occasions over the past 10
years. These instruments work on the same principle as the total station to measure angles and distances
from known control points to points of interest on the rock. They use a laser beam reflected from the rock
to measure the distances without need of a prism at each point. This allows for measuring huge numbers of
points very quickly and accurately to build 'digital models' of the mountain in our engineering computers.
The next step in measuring on the mountain will be to apply the best possible methods to measure the geologic
structure of the mountain in addition to the basic geometry of the mountain. This information becomes
critical in refining the shape of the models and in planning for long term stability of the memorial.
Remove all the rock that doesn't fit
Rock is removed from the mountain primarily with explosives. Again this complex process can be summed up in basic steps:
Drill precisely placed holes in the granite; load explosives in the holes; time the detonation sequence of those
explosives; push the blasted rock (known as 'muck' in the mining industry) off the mountain with heavy equipment
and finally remove the last layer of rock in the finishing stage. All blasts at Crazy Horse are designed, drilled
and executed to protect the rock that is left after the blast. This is the opposite of most blasting operations,
where the main concern is the final size and location of the material being blasted away. The mountain crew prepares
most blasts using a system that explosives engineers call "pre-splitting." It is similar to perforating a piece of
paper to allow it to tear evenly. The rock to be removed is drilled on all sides with a series of parallel drill
holes. Explosives are detonated throughout the entire length of each of the drill holes, cleanly removing the
desired rock while leaving the remaining rock undamaged. Here's a more detailed look at each of the steps in
the rock removal process:
Drilling
Equipment has evolved from Korczak's use of a single-jack (sledge hammer and hand steel) to drill the
holes for the first blast on the mountain. Korczak quickly advanced to pneumatic jack hammer drills powered by
'Buda', the ancient air compressor which quit frequently during the work day and forced him to make many trips down
and back up the 741 steps to the top of the mountain. He then progressed to wagon drills, a larger drifter
drill mounted on a D8 Cat and finally air track drills. These machines required less manual labor but still
relied on gas or diesel powered air compressors to drive the hammer. The mountain crew did much of the drilling
for Crazy Horse's face using hand held rotary hammer drills powered by more modern, efficient electric air compressors.
We still drill 1 3/8 inch or 1 5/8 inch holes up to 21 feet deep using these hand drills on rare occasions
when the track drills cannot be maneuvered to the drilling site. Hydraulic drills are now the standard
and our fleet includes three of these very efficient machines mounted on tracks or rubber tires. Most of
our holes are drilled about 20 feet deep using 2 inch diameter carbide steel bits. Our largest machines
approach drilling rates up to 10 feet per minute! The next generation of these drills will be faster and
more efficient and will have enclosed cabs to better protect the mountain crew from the noise and dust generated
in the drilling process.
Explosives loading
When most people think of explosives, they imagine dynamite. The primary types of
explosives used here at Crazy Horse, however, are not dynamites but detonating cord and small diameter water
gel or emulsion based pre-split products. Dynamite is very effective at fragmenting rock, but expends all
of its energy in an area equal to the length of the cartridge - a very small portion of the drill hole.
Our blasts using detonating cord and pre-split products can be designed to expend the same amount of energy
over the entire length of the drill holes. This provides much better control of the explosive energy and
does much less damage to the rock that is not removed by the blast. In a typical blast at Crazy Horse up
to several hundred drill holes are loaded with the appropriate size of detonating cord or pre-split
explosives. After the product is in place the holes are filled with small crushed stone. The stone
fills the open space in the hole and better focuses the explosive energy to precisely split the rock.
Blast timing
The typical blast is actually a carefully timed series of smaller blasts spaced only a few
milliseconds apart. The vibration and damage caused by the blast can be controlled by limiting the amount
of explosive detonated in each section of the blast. The distance to what will be the finished surface of
the mountain carving ("final grade") dictates the distance between drill holes and the type and amount of
explosive used in each hole. The closer to final grade, the smaller the drill hole spacing and the smaller
the explosives charge weight in each hole. Timing between the blast sections is controlled by the blasting
caps (detonators). This is another area where advancing technology is making a big difference in our mountain
carving operation. Electric blasting caps which are susceptible to premature detonation caused by static
or nearby lightning strikes or radio transmissions are no longer used. Our most common method uses
non-electric delay detonators fired by sending a spark through long plastic tube or with a highly secure
2-way radio controlled remote initiation system. We have also used the latest technology - a system of
electronically controlled, programmable detonators which allow nearly infinite choices in blast timing.
We expect systems like this to play a key role in controlling blasts as we work closer to finished grade
in the future.
Mucking
Removing the blasted rock or muck from the mountain is accomplished with heavy equipment.
Here again there has been a steady improvement in the type, size and efficiency of the equipment used
over the past 60 years. A typical blast today produces 2000 to 3000 tons of rock fragments. These
rocks range in size from small gravel up to the occasional 10 ton boulder and most remain on the blasting
bench rather than falling off the mountain from the force of the blast. The mountain crew spends 2 or 3
days with a combination of excavators and bulldozers to move this rock off the mountain and clear the way
for the drills to prepare the next blast. To lend some perspective to the quantity of rock being handled - the
average dump truck on the highway is hauling about 15 tons of material. It would take 200 truck loads to haul
away the rock from just one large blast on the mountain!
Finishing
When the crew returns to finishing work it will be accomplished as it was on Crazy Horse's face by
drilling to isolate small blocks of rock (100 to 1,000 pound chunks). These blocks may be blasted off using very
light explosives. In very detailed areas of the carving, drill holes are located so close together that they
almost contact each other and mechanical wedges are used as an alternative to explosives.
A jet torch is used to finish the surface of the mountain carving. The jet removes drill marks and
smoothes the final surface. The torch runs on diesel fuel and compressed air. The 3,300 degree (F) jet
flame causes tiny fragments of rock to flake off as the result of heat expansion, leaving a polished surface.
The variety of minerals in the pegmatite granite makes torching a challenge because each mineral reacts
differently to the heat.
The final step in finishing is to seal the natural seams in the granite so that water cannot infiltrate
and cause damage during freeze/thaw cycles.
Crazy Horse Memorial has received many generous gifts of equipment, explosives and technical services over the
years. In the past few years, for example, donations and significant discounts have been received from the
following companies:
Equipment
Caterpillar
Case
John Deere
Atlas Copco CMT
Sandvik Mining & Construction
RDH Mining Equipment
Atlas Copco Compressors
Gardner Denver Compressors
Kuefler Lightning Protection
Erico
Sioux Steam Cleaner Corp
East Coast Drilling
Martin Marietta
|
Explosives & blasting technology
Dyno Nobel
Orica USA
Buckley Powder Company
Austin Powder Company
Alpha Explosives
Intermountain West Energies
Wampum Hardware
Instantel
Blastronics
Davey Bickford USA
Rothenbuhler Engineering
|
Measuring & engineering technology
AutoCAD
Eagle Point Software
Real Earth Models
Direct Dimensions
FARO
Thatcher & Associates
Trimble
Vibronics
Engineered Dimensions
Lamp, Rynearson |
The primary source of funding for the work of carving Crazy Horse comes from visitor admission fees.
Generous contributions from corporations provide critical additional resources to make continued work
on the mountain carving possible.
