(RPM) - If the speed is too high the bit will polish. If the speed is too low the job will take too long. You will know if the bit is "Polished" or "Glazed" when it stops cutting, you have segments left, and you don't see exposed diamonds. To open up the diamonds try drilling in soft abrasive material like a cinder block. Be careful to not drill very much as you will be wasting diamonds.

Necessary to maintain the proper cutting speed. Efficient cutting means keeping the bit at the right speed.

Not too little and not too much. The right amount removes slurry and keeps the cut clean. Slurry water should look like "Coffee with cream"

You can't see it until you're done, but a good driller can feel the right speed and pressure to cut varying types of aggregate.

Slows down the cutting process. Maintaining drill motor speed is important. Don't push the bit too hard. Maintain even speed with even pressure.

Too hard and it takes too long. Too soft and it costs too much money. Remember Hard bond for cutting soft abrasive materials, soft bond for cutting hard materials. "Hard on hard" won't cut, and "soft on soft" won't last.

Necessary for good bit life. This means the rig must be properly anchored. A rig can be anchored with concrete anchors, vacuum or a post jack.
Standing on the rig is DANGEROUS and not acceptable

Performance, speed and bit life will mean little if your rig has bad shims, bearing and hold down devices.