How to Bullnose Around a Windowsill

Create Bullnose on the Sill

• 1

  Insert a quarter round bit into a router. The radius of the bit should be half the thickness of the windowsill or less.

• 2

  Run the router along the length of the top of the windowsill, creating a quarter round profile. Repeat the process on the bottom of the windowsill to create a half round profile.

• 3

  Form the bullnose profile on the sides of the windowsill in the same way. You won't be able to run the bit all the way to the wall because the body of the router will get in the way. Finish the part you can't reach with the router by using a sharp chisel and sandpaper.

Add Bullnose to the Sill

• 4

  Use a router mounted on a router table to make a piece of trim that is flat on one side with a half round profile on the other side. Make the piece long enough to accommodate both the front and the sides of the windowsill where you will be applying it.

• 5

  Cut a piece of the trim with a 45-degree angle on both ends, with the inside measurement the same as the width of the windowsill.

• 6

  Add this piece of trim to the front of the windowsill with glue and finish nails.

• 7

  Cut a piece of trim with a 90-degree angle on one end and a 45-degree angle on the other end to fit on the left side of the windowsill, running from the wall to the 45-degree angle of the first piece you installed. Attach this piece with glue and finish nails.

• 8

  Repeat Step 4 for the right side of the windowsill.

• 9

  Clean up and smooth all joints and surfaces with sandpaper.