DIY Network

1. Cut a hole in the jig board (figure D) so the blade can come through.

2. Make marks down the length of the jig one inch apart, starting from the place where the bit goes through the jig.

3. When using the jig, if you put your nail at the six inch mark, you'll be able to cut a 12 inch diameter circle.
   

Making a jig with a band saw

1. First, build a sled (figure E) that fits over the top of the table. Its size will depend on the size of the circle. (The sled consists of a carrier board to which a stop block is attached. The stop block will rest against the edge of the table. There's also a piece of hardwood attached to the bottom of the sled that fits into the miter slot in the table.)

2. After putting all the pieces together, you will need to slide the bar into the miter slot and cut a kerf into the sled.

3. The saw will stop when the stop block reaches the end of the table.

4. Next, draw your marks at one or two inch intervals from the blade. This will give you the radius of your circle.

5. After marking the appropriate radius for the size circle you need, drill a small hole into the sled.

6. Take the brad with the head cut off, and drop it into the hole upside down, with the point coming up out of the hole.

7. Locate the center of the board you're cutting into, and then make a mark. This is where you will align your board with the blade.

8. Tap the board with a hammer to insert the brad. The brad will become the pivot point of your circle when you make the cut.