hairline crack emanating from the hole and connecting some or all of the
other holes. Remember, holes intended to be shot always need to be
cleaned thoroughly just before loading and firing. The other holes not
shot do not require cleaning. A second shot can be done in one of the
other holes as long as the crack connecting the holes is not too large
which will allow the expanding gases from the 2nd initiated cartridge to
escape too rapidly through the crack.
If the second shot does not open or extend the original hairline crack
from the first shot two options need to be considered. The crack may be
allowing too much of the gas to escape or the spacing of the drilled
holes needs to be reduced. If you decide that too much gas is escaping
you will now need to use the tapered pins supplied in the Micro-
Blaster™ kit to wedge apart the rock. For most rocks placement of the
two pins at 1/3 intervals along the line of holes and hammering
alternately on each pin should finish the split. For especially large rocks
more pins may be called for to exert greater splitting force.
In general softer materials will need the holes to be drilled closer
together than the harder materials. This is primarily because the softer
materials tend to absorb more of the energy developed by the Micro-
Blaster™ cartridge. Concrete, partly because of its relative softness and
the presence of the aggregate within (which breaks up the fracture
lines), may require hole spacing as close as six inches. Very hard fine
grained rock such as granite or limestone may be effectively cracked
with hole spacing as much as eighteen to twenty four inches. When
breaking rock with distinct layers, holes drilled parallel to the layers are
often more effective than holes drilled at right angles to or through the
layers (i.e. sandstones).
After some experience using the Micro-Blaster™ with specific
materials the spacing of holes will become more predictable.
Furthermore an organized and methodical approach to your projects will
greatly improve productivity. Always check the firing pin for free
movement to avoid misfires and observe all safety precautions.
Breaking Larger Rock Using 2 Cartridges in the Same Hole
On projects where the breaking of larger rock or softer materials (i.e.
concrete) must be broken, the use of 2 Micro-Blaster Cartridges in the
same hole has proven to be extremely effective. We estimate that a
fourfold increase in the effective power can be expected over the use of
a single cartridge in a hole. When anticipating that more than one
cartridge will be required to effectively crack the material at hand, the
5/16” dia. holes should be drilled to a depth of 12” and then cleaned in
the usual way .
Never use more than 2 cartridges in the same hole
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