Use our professional Kerf Bend Calculator to accurately determine the number of saw cuts and the precise spacing required to bend any wood thickness to a specific radius. Perfect for cabinetry, furniture making, and architectural millwork.
Kerf Bend Calculator
Kerf Bend Calculator Formula
Cuts (N) = (Thickness × Angle_rad) / Kerf
Spacing (S) = (Radius × Angle_rad) / N
Source: Fine Woodworking Reference | Wood Magazine Technical Guides
Variables Explained
- Material Thickness: The total thickness of the wood board you intend to bend.
- Inside Bend Radius: The radius of the inner curve after the wood is bent.
- Bend Angle: The total angle of the bend (e.g., 90° for a right-angle corner).
- Kerf Width: The thickness of the material removed by your saw blade.
What is a Kerf Bend Calculator?
A Kerf Bend Calculator is an essential tool for woodworkers that calculates how much material needs to be removed from a board to allow it to curve smoothly. By cutting a series of slots (kerfs) into the back of a piece of wood, you reduce its structural resistance, allowing it to conform to a specific radius without snapping.
This method is widely used in creating curved cabinetry, rounded stair treads, and custom musical instruments. Accuracy is critical; if the kerfs are too far apart, the curve will be faceted (not smooth). If they are too deep or too close, the wood may break during the bending process.
How to Calculate Kerf Bending (Example)
- Measure your Material Thickness (e.g., 20mm).
- Determine your desired Inside Radius (e.g., 100mm) and Angle (90°).
- Check your Saw Blade Kerf (usually 3.2mm for standard table saws).
- Calculate the difference between the outer arc and inner arc lengths.
- Divide that difference by the Kerf width to find the number of cuts needed.
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Frequently Asked Questions (FAQ)
Is kerf bending as strong as steam bending? Generally, no. Kerf bending removes material, making the wood weaker. However, it is much easier for DIY projects and can be reinforced with veneer.
How deep should I cut the kerf? You should leave about 1/8″ to 1/16″ (2-3mm) of “meat” at the bottom of the cut to act as a hinge.
Can I use this for any wood? Yes, but hardwoods like Oak or Walnut bend differently than softwoods or plywood. Always test on a scrap piece first.
What if my calculation results in a decimal for the number of cuts? Always round up to the nearest whole number to ensure a smooth curve.