Diamond Products CB215 Parts List & Operator’s Manual page 12

WARNING: Always keep your face away from the machine.
The diamond impregnated segments in a wet type (sintered) diamond core bit operate on a principle of controlled erosion. The bond
matrix holding the diamonds is continually worn away by abrasion with the work piece, exposing the harder diamonds to stand proud
from the bond matrix.
Without adequate water, the bit would overheat and be destroyed.
With too much water and not enough feed pressure, there would not be adequate erosion of the bond matrix and the bit becomes dull.
This is called glazing. If the bit seems to refuse to cut anymore, it is glazed. See below: "SHARPENING A GLAZED BIT "
Don't feed too gently or the diamond segments will become glazed. Keep the bit steadily working.
If holding by hand, take great care to keep the bit aligned to the hole. If the bit is crooked, it will easily bind.
If the cut is very deep, the core plug may be obstructing the flow of cooling water. In this case, stop drilling, and chisel out the core plug
before continuing.
CAUTION: If the bit gets stuck, do not try to rock it loose by turning the switch on and off. That is hazardous and could damage
the motor. Rather, unplug the machine and use a wrench on the bit mounting to work it loose.
If embedded steel such as rebar is encountered, take special care. Reduce the feed pressure by about 1/3 and let the bit go at its own
pace. If there is too much vibration, the bit will be destroyed.
Once the steel is passed, continue normally.
CAUTION: Drilling operations are very stressful to the motor and at the end of the cut, the motor temperature will be very hot,
always run the motor at no load for a few minutes until the temperature returns to a normal range before shutting off.
RESHARPENING A GLAZED BIT
If the bit becomes glazed, resharpen by dressing with an appropriate alumina oxide or silicon carbide dressing stone. Simply drill into the
stone as many times as necessary to restore its cutting performance.
VIBRATION TROUBLESHOOTING
If vibration occurs and it is not caused by embedded steel, stop drilling to find the cause and remedy.
CAUTION: Do not operate with vibration or there will be serious hazard and the diamond core bit will surely be destroyed.
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