With the outside of the bowl shaped to your preferred profile, we need to set up the bottom of the bowl so it can be placed back on the lathe. This will allow removal of material from the interior of the container. This is called a reverse chuck, and a four-jaw offset chuck is used to clamp the bowl to your lathe with the inside of the bowl toward the tailstock. The bottom of the bowl has been turned flat and square on the lathe; Twist a spigot about ½-inch tall into the bottom of the container. I prefer to use a large diameter spigot and then create a recessed dovetail cut in the spigot about 3/8 inch deep. The dovetail diameter must be within the range of travel of your Scroll Chuck Jaws. For heavy bowls, I prefer the recessed dovetail; this method is stronger. Smaller bowls can be turned with a smaller faucet and hold onto the outside of the faucet.

Remove the bowl from the lathe and remove the face plate and set the chuck in the dovetail hole. better way; is to connect the chuck to the bowl before connecting the offset chuck to the lathe, this ensures better alignment. Then connect the chuck to the head. If the chuck is not positioned correctly in the dovetail hole, the bowl will wobble. A slight wobble is okay because the bowl will reset itself after it dries. The jaws are numbered on the offset chuck; Mark the bottom of the container to correspond with one of the jaws so that it can be put back in the same position after drying.

After the bowl has been attached to the offset chuck and connected to the lathe headstock. Natural edge bowls have a smooth surface and will put a lot of stress on the chuck’s holding ability when you start turning the inside. For safety and to help support the bowl, use the tailstock for support, same procedure as item 2.

Place the banjo between the bowl and the tailpiece; With the tool rest at the proper height, rotate the bowl by hand to ensure that the bowl can rotate freely. Using a bowl gouge and starting near the live center of the 60 degree cone, carefully and slowly start cutting the inside of the bowl, once you have some depth and the cut is even you can move faster. As you get further into the bowl, you will need to move the tool holder closer to the surface of your work area. If any tool extends beyond the tool rest, it will cause a lot of vibration.

The distance a tool can extend beyond the tool holder is related to the size of the tool you are using, it is best to follow the manufacturer’s recommendations. Large diameter tools can extend further into the tool holder than a small diameter tool; same thickness.

The container should be dried after the material inside the container has been removed; this will be discussed in the next article. The thickness should be about 1 inch thick, sides and bottom, except for the dovetail hole, which should be thicker. At this point much of the weight has been removed and you can take out the tailstock. The tap left inside the bowl can be removed using a bowl gouge or I prefer to use a large Forstner bit. Using a chuck mounted on the tailstock shank, you can advance the bit and remove any remaining wood; a horizontal drill. When the inside of the container is uniform; use the round-tipped scraper to smooth the inside of the bowl.

The attached link is a glossary of terminology for the lathe and associated tools; http://www.turningtools.co.uk/glossary/glossary.html