Helpful Hints for Using Metal Bond Core Drills

When mounting a core drill make sure drill chuck or water swivel unit is clean and free of any burrs so the bit will run true.

Always make sure work piece is held firmly to avoid drill from “walking” and also to avoid accidents while drilling

Always use coolant while drilling, either through a center feed water swivel or a spray type mist. You can also drill under water in a tank. DO NOT DRILL DRY!!! The bit or your work piece will BREAK!

Determine the proper RPM. This is vital to successful core drilling. Use the chart at the bottom of this sheet.

DO NOT use too much pressure. Unlike steel or carbide twist drills, diamond core drills do not cut material, they grind the metal away. Diamond bits cut at their own pace. The “PECK” cutting method is the best. Constant down pressure will cause the bit to load and break your work piece and or the bit.

Diamond bits need to be dressed. If cutting action slows or you hear a squealing sound the bit is most likely loaded. The drill bit needs to be dressed with an aluminum oxide dressing stick. Let the bit cut into the dressing stick to clean the cutting area and expose fresh particles of diamond. You can never over dress a core drill.

Do not allow the bit to become rusty. Rust formed on the ID or OD of the steel tubing will cause the bit to bind in the work piece.

On some harder material it is also suggested that slots are put in the diamond section to improve the cutting action. Check with the manufacturer as to the type of material you are cutting.

Suggested RPM’s

Basic Rule – The smaller the OD, the faster the bit needs to run, larger OD the slower the bit needs to run.

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