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Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →To lay out an irregular woodworking curve, bend a flexible spline through the curve’s marked points, secure it with movable blocks, and trace its edge onto a template blank. The blocks let you push or pull the spline into both inward and outward bends. Jan Svec’s WOOD magazine method, updated February 1, 2026, works whether a drawing supplies intermediate points or you are shaping a curve from its endpoints.
Materials and layout
Use a template blank larger than the finished curve, a flexible spline, scrap wood for movable blocks, and screws. Svec’s example uses a 1/4 × 12 × 36-inch hardboard blank and a 1 1/2 × 36-inch plastic-laminate spline strip. These are example dimensions, not required sizes; choose a blank and spline suited to the project. A combination square is useful for transferring dimensions from a drawing.
- Mark the curve’s beginning and end on the blank.
- If a drawing provides intermediate points or horizontal and vertical dimensions, transfer those marks as well.
- If you are designing the curve yourself and know only its endpoints, mark them first and compose the shape between them by adjusting the spline.
Make the movable blocks
Cut enough simple scrap-wood blocks—called “ducks” in the article—to position one every 6 inches along the spline. Leave the two end blocks square-ended so you can make finer adjustments near the curve’s ends. Cut 45-degree points on the intermediate blocks to reduce flat spots where the blocks meet the spline.
Drill shank holes through the spline at 6-inch intervals and matching pilot holes in the blocks. Svec also suggests adhering sandpaper to the bottoms of the blocks to help keep them from sliding on the blank.
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Shape and trace the curve
- Set the end blocks. Place the spline over the layout marks and attach the end blocks tightly.
- Adjust the intermediate blocks. Leave them slightly loose while you push or pull the spline until it passes through the marked points. Move the spline gradually and check the full curve, including its transitions, before fixing the layout.
- Hold the shape. Secure the blocks in position so the spline cannot shift; the article uses bricks as weights.
- Trace the edge. Draw along the spline onto the template blank.
- Cut and refine. Cut the blank along the traced line with a bandsaw or jigsaw, then sand the edge to the finished curve.
What this method does—and does not establish
The blocks allow the spline to bend inward and outward, making the method useful for irregular curves rather than only a single convex arc. It is a hand-layout approach. Svec’s article does not establish comparative accuracy, speed, or cost versus CAD or other curve-layout methods, so choose a layout approach based on the points and tools your project requires.
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