The V-Cone. To determine the actual air volume (CFM) being produced, a flow meter such as a V-Cone from McCrometer can be very useful. The V-Cone conditions the air flowing through the string, and creates laminar flow (straight flowing air). It measures the pressure above the cone, then again below the cone, and converts the difference in pressure to a velocity measurement, which is later used to calculate the volume.The inside of the “V-Cone” flow meter by McCrometer.

Determining Your Specific Air Requirements, do you want to concentrate on clearing the cuttings from the cones or...


The drill machine turns the steel, the steel turns the bit, the bit turns the cones. Weight is applied by the drill + the weight of the drill string. The total weight pushes the carbide buttons in the 3 cones, into the rock. The bit carbides must stress the rock to make the rock fail to create chips. Air (pressure) flushes the chips away from the buttons and air volume pushes them up and out of the hole.

Drilling Parameters:
1. WOB = Weight on bit
2. RPM = Revolutions per minute
3. Air = Pressure (psi) and Volume (cfm)
4. ROP = Rate of...

When breaking in a new bit, make sure that In the first 1/3rd of the depth of the first drilled hole use 1/3rd of regular pull-down pressure & 1/3rd regular rpm. In the second 1/3rd of the depth of the first hole use 2/3rd of regular pull-down pressure & 2/3rd regular RPM. In the final 1/3rd of the depth of the first hole use regular pull-down pressure & regular rpm. The bit is now ready to drill with normal operating parameters.

Some other things to consider:
1. Do not drop bits as damage to bearing, cutting structure and threads can result.
2. Protect the...