Why carbide bits bite the dust

Pushing bits beyond their limits? Look for these telltale signs.

Carbide bits take a beating every time they are used. Rotary hammers literally pound them into the concrete when drilling holes.

Carbide bits face tough duty, but often, operators don’t do them any favors, either, says Gary Compton, Milwaukee Electric Tool product manager.

“The No. 1 killer is attempting to use the carbide bit to cut through rebar. The hammering action pits carbide against steel. The carbide tips are hard, but they are designed for striking or breaking rather than cutting so the hammering action can quickly dull or deform the tip when it hits steel.

“Operator technique greatly affects the life of carbide-tipped bits. Pushing the bit too hard instead of applying just enough pressure to keep the unit from bouncing can cause the bit to bend or break, particularly with small-diameter or long bits,” he says.

The following photos show damage often inflicted upon carbide bits. Much of it is caused by side-loading, hitting rebar or pushing too hard on the bit.

In most instances, this type of damage is not covered by the manufacturers’ warranties.

However, there are a few types of bit damage that may be manufacturing defects, which are often covered by the manufacturer’s warranty. When in doubt, contact your distributor for advice.

Published in the July/August 2001 issue of Contractor Tools and Supplies magazine.

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