Diamond Blade Dos & Don'ts

By Rebecca Kanable, contributing writer

Diamond blades get beat up in a variety of ways. They get burned, stuck (and then hit with a hammer), bent and broken. It's not pretty and it's not good practice.

Whether you're using a diamond blade on a gas-powered saw, electric hand saw or walk-behind saw, a few words of wisdom can help save blades from misuse and abuse.

Factors affecting longevity
Blade life can vary greatly depending on a number of variables. One key factor is blade quality (diamond quality and concentration, and segment bond and width). Consider that two blades of the same diameter could have different diamond depths, amounts of diamond in the blade segment and segment heights.

As with traditional diamonds, there are different grades assigned to synthetic diamonds for saw blades. "A higher-quality diamond is going to perform better and definitely last longer," says Ted Skaff of Pearl Abrasive Co. In some cases, it may also grind or cut faster, as well.

Another key factor in blade life is the material that needs to be cut. Cutting a hard material such as concrete requires a different blade than one used to cut a soft, abrasive material such as asphalt. The harder material requires diamonds to be exposed more quickly, and a softer bond to hold the diamonds to the segment.

"You could use a blade designed for concrete to cut asphalt and it will cut really fast, but it won't last very long," says Thom Fisher with Diamond Products.

How concrete cutting impacts blade life depends on the aggregate size, sand type (sharp and abrasive or round and non-abrasive), aggregate hardness (determined by rock type) and reinforcing steel (amount, grade and gauge). For example, a coarser aggregate with a lot of sand will wear a blade faster than concrete with less sand and less aggregate, Skaff says.

However, softer and more abrasive green concrete will require a harder bond with undercut protection, Fisher adds.

How long a blade will be useful on a job depends on the amount of cutting that needs to be done. Using a blade to cut a driveway is different than using a blade to cut a long stretch of highway, Fisher points out.

The saw used with the blade also affects blade life. A tool with high rpm will wear a blade faster than a tool with low rpm, Skaff says.

The operator can shorten the life of a blade, as well. An operator applying more pressure will tend to wear out a blade faster than someone applying less pressure, Skaff says.

Tips for longer life
Given these variables, manufacturers offer the following dos and don'ts to maximize blade life.

Do use the right blade for the job. There are blades designed specifically to cut concrete, masonry and green concrete.

While general-purpose blades can cover a variety of cutting tasks, application-specific blades are engineered with a specific bond to meet the needs of a certain application. They do the best job and will last longer, Skaff says.

To help find the right blade for the task, Hobie Smith of MK Diamond Products Inc. suggests answering the following questions:

• What material are you cutting?
• What type of cutting equipment will be used?
• How much cutting will be done?
• How fast do you need to complete the job?

Do use a wet blade only when wet. A common operating mistake is using a wet blade dry. "A wet blade should never be used dry," Skaff says.

Fisher agrees, noting, "We get blades back all the time that are fried because water wasn't used. It doesn't take very long for the friction of concrete (or even asphalt) to burn up a blade."

Even dry blades can be used wet; doing so might actually increase production and blade life. Heat and dust are enemies of a blade, Skaff explains. Using a blade wet eliminates both enemies.

Don't bury the blade. Another common mistake is burying the blade all the way to the flange, or forcing the blade through the material being cut.