CORE DRILLING OPERATION • Mount the drilling motor on the rig. • Use a quick-release ring between the motor and core bit to prevent blockage after work. • Set the proper rotation speed depending on the drilling diameter. • Plug to water supply and set a sufficient supply of water to ensure that hole will be constantly flushed of abrasive slurrys. • Plug the three-pronged plug (PRCD) on the power cord of the motor into a grounded electrical outlet of the appropriate voltage. • Slowly lower the bit into the cut so that there is no skidding or lateral movement of the core bit. The entire circumference of the core bit should penetrate the drilling surface before additional pressure is applied to the handle. • Exert steady downward pressure onto the core bit whilst drilling. Do not force the core bit into the material. • Do not stop the flow of water or the rotation of the core bit as long as the core bit is in the hole. If the drilling rate decreases noticeably, check the core bit. The slower penetration rate generally means that the core bit is dull and needs to be reconditioned. In most cases, core drilling requires the use of water. Properly ground the core drill, as the use of any electrical tools in wet areas can be hazardous. The core drill must be securely fastened to the intended work surface (wall, deck, etc.), using anchor bolts, vacuum pad or jack screw. Use extreme caution when drilling through floors. Check for electrical conduit. Provide protection for all personnel and materials below the areas being drilled. OPTIMAL RPM FOR DIAMOND CORE BITS Masonry Concrete Rotation speed (RPM) Core bits diameter (mm) Peripheral speed (m/s) 314
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