How to Scribe an Arch Using a Lath

Fitting the Lath

• 1

  Cut a piece of wooden lath to length with a miter saw; it should be a few inches longer than the diameter of your intended arch. Use a tape measure to make a mark in the center of one end of the lath. Use a rafter square to mark the lath 1 inch in from the end, in line with the center mark.

• 2

  Measure from the 1-inch mark the distance of the diameter of arch you want to make. Make a second mark at that distance, centered in the width of the lath. Drill a 1/8-inch hole on each of the two marks.

• 3

  Position the lath on a sheet of plywood (or other material large enough to hold your arch). Drive one screw through one of the holes, so that the other end of the lath is free to swing on top of the material. Don't over-tighten the screw. It should be snug enough to hold the lath firmly in place, while still allowing it to swing freely.

Scribing the Arch

• 4

  Fit an awl into the hole at the end of the lath opposite the screw that holds it in place. Drag the point of the awl along the surface of the material, applying slight pressure to scribe the surface in a perfect arch.

• 5

  Create an inside, parallel arch at any thickness by measuring in from the first awl hole and drilling a second. Fit the awl through the hole and drag it along the swing of the lath in the new hole, scribing a perfect arch, parallel to the first.

• 6

  Remove the screw when the arch is complete. The lath can be reused to create arches of any diameter simply by drilling another hole at the correct measurement.