Flattening and Tensioning Circular Knives and Saw Blades

Circular knife cutting wood

Many people fail to understand the importance of the correct blade flatness and tension in providing a consistent cut. The fact is, a flat blade plays a critical role in the quality of your final product. Flattening and tensioning your blades provides improved performance in any cutting application, as it assures that the blades will run at operating speeds without wobbling.

We’ve put together this guide to help you get a better understanding of the steps we use to flatten your knives and blades, as well as our post-flattening inspection process. While each of our blades is created unique to your specific needs, every blade undergoes this strict flattening and inspection process for the utmost quality and longevity.

Circular knife with text overlay

How to Flatten Saw Blades

Without the proper flattening techniques, everyday wear and tear can cause saw blades to wave and bend. Our Anvil Room Technicians manufacture our blades using equipment that ensures proper flatness. A precision flattening machine is used to flatten out any inconsistencies in the blade, while final touches are performed by hand with a precision hammer.

We use marking and measuring equipment specifically designed for our industry to determine whether a blade needs to be flattened. This equipment shows us not only if the blade is bent or has tension areas, but also the extent of problem sites and where they’re located, as well as whether the saw is running on the center line.

After we’ve determined that the blade needs corrective action, our state-of-the-art equipment levels and checks for proper tension. Afterward, we use an anvil and a precision handmade hammer to perform the final touches on problem sites, keeping in mind that the hammer should have a soft, round striking surface to avoid shortening the service life of the blade.

Hitting a saw blade with a hammer stretches and expands the metal — never contracts it — and different hammer sizes and amounts of force can also affect the final product. We’re always aware of what needs to be done and how far the material needs to be stretched before beginning.

Circular knife

Different face grind configurations like Dog Head & Twist are used to bring blades flat, while different hammer weights are used to match thickness:

  • 1,250 g hammer for blades 1.65 mm or less
  • 1,500 g hammer for blades over 1.65 mm

Once we choose a hammer, we use the following steps to flatten the blade:

  1. Place the blade on the anvil. Hammer down all ridges or lumps while using as few blows as possible to avoid expanding the metal too severely.
  2. If there’s a loose area, mark it and hammer between the mark and the blade’s rim to stretch out unnecessary tension.
  3. If there’s a tight spot under the straightedge, we hammer it on both sides to increase the tension.

Every custom blade we make is different, and our anvil room technicians have the expertise necessary to diagnose and repair individual problems. By the time the process is complete, your blade is expertly flattened to handle your precise applications with the closest flatness tolerances.

Post-Flattening Inspections

Our blades are inspected for flatness numerous times throughout the manufacturing processes. Our technicians are provided specially lighted inspection work areas that reveal any inconsistencies in the body of the blades.

Flattening and Tensioning in the Manufacturing Process

After the heat treating and grinding processes, stresses can be revealed within the blade. At York Saw & Knife, we use proven techniques to ensure that our knives and blades are flat and run true at operation speeds. To correct flatness, we utilize state of the art Leveling & Tensioning machines designed and built exclusively for our industry. This equipment assists our Anvil Room Technicians by reducing man hours for the final touch hammering/smithing of blades to ensure that all blades meet flatness run-out tolerances.

If you’re interested in learning more about our manufacturing process, click here!

If you’re ready to ensure that your custom round blades are appropriately tensioned and flattened for the most efficient productivity, request a free quote online or call us today.