Ball finials are staples when it comes to making rods, ball posts, fences or anything that has height. Although ball finials look very intimidating to make, they're actually quite easy to form. All you need is a wooden block to start with. Picking out the wood is probably the most crucial step. You want to get one that isn't too soft, but is still workable.
Step 1 - Pick the Right Rectangular Block
Your rectangular block's size will affect the outcome of your ball. The general rule is you want to find a rectangle that is approximately 1/8" larger in width and at least 2" longer compared to the finished ball. For example, if you are thinking of making a 3" ball, find a rectangular block that is 3-1/8" by 3-1/8" by 5".
Step 2 - Cut the Corners
Place your block on the center of the bandsaw's lathe. Cut off the sides so that your block becomes a cylinder.
Step 3 - Make Trunnions on the Ball
Make trunnions on both sides of the ball. The trunnions should be about 1" in length. This should reduce your rectangle into 3 inches.
Step 4 - Make the Rectangle into an Octagon
When turning a block into an octagon, it's important to know the tangent of an octagon's angle and the length of each side. An octagon's angle is 22.5 degrees, which makes its tangent 0.41. Multiply 0.41 by the diameter of your ball. In this case, multiply 0.41 by 3. You will get the length of each side. For this example, it is 1.23 inches. Use a pencil to mark the sides. Once you have the octagon, add eight more sides to it to make the wood 16-sided.
Step 5 - Make the 16-Sided Wood Round
Once you have the 16 sides, carefully round everything into a circle. You may have to carve through the trunnions, but carve as little as you can out of it.
Step 6 - Remove the Trunnions
Take off at least half of the trunnions from the wood with the use of a pull saw.
Step 7 - Smooth the Ball
With the use of scrap ash, create a jam chuck with a hole that is deep enough to hold a segment of the ball. Place the jam chuck on the face plate. Now place a ball bearing cup shape on the tailstock. Attach the ball to the tail stock and smooth the ball with the use of the jam chuck. Remove the remaining trunnions.
Step 8 - Attach the Ball to the Base
You can carve out a wooden base for your ball in order to finish making the wooden ball finial. Use your own creativity when it comes to designing the base. Use wood glue to attach the ball to the base. Allow to dry, then sand everything down.