The Hollowing Process
Whichever tools you use, the basic approach for creating a hollowed vessel is straightforward: Turn the outside shape of your vessel first, then hollow out the inside until you’ve reached the desired wall thickness. There are other factors involved, of course, and some turning experience is a must, but here are some general pointers to get you started:
Mount the Workpiece:
Mount the piece securely on a faceplate, screw chuck or scroll chuck. It’s a good idea to use a live center in the tailstock to help support the piece as you turn the outside shape, usually with bowl gouges.
I prefer to turn green wood, because it cuts a lot easier and generates less heat than dry wood, but plenty of people turn dry. You can orient the workpiece with the grain either parallel or perpendicular to the axis of the lathe. Most turners prefer perpendicular, or “bowl,” orientation, with or without the pith included. Green wood that is turned for cross-grain work. It also makes these tools grabby and apt to dig in and catch if you aren’t careful. For this reason, many of the tools in this category come with adjustable shields over the cutter to limit the depth of cut.
The Hollowing Process
Whichever tools you use, the basic approach for creating a hollowed vessel is from “green to finished” in one session tends to shrink to a slightly irregular or ovoid shape after you’ve hollowed it, which can be quite interesting. Dry blanks, of course, will stay more circular after they’re turned.
Open the Center:
Begin the hollowing process by creating a hole in the center of the workpiece, either with a drill bit mounted in a chuck in the tailstock or with a straight scraper tool plunged in from the end. You don’t need to bore all the way to the bottom until after you’ve hollowed the upper areas of the form.
Work Your Way Down:
Hollow the inside of your vessel with a combination of straight tools near the bottom and bent tools on the sides and in the shoulder area. Begin near the top and continue downward in increments, working the tip of the tool in whichever direction works best for you.
You’ll have to stop frequently to clear the chips that accumulate inside the vessel, otherwise they will eventually seize up around your hollowing tool and could result in damage to your vessel or worse. I stop the lathe whenever the chips need clearing, and then blow them out with a long-nosed air gun attached to my compressor.
Many turners like to hollow the upper neck and shoulder areas before continuing to the lower sections of a piece. This method reduces vibration and chatter and provides the best support for the delicate walls of your vessel as you approach final wall thickness.
It’s a good idea to check that wall thickness frequently, especially when you get close to your target thickness. A piece of stiff wire bent into a rudimentary caliper works fine for this, although more elaborate gauges are available.
Once the inside of the piece has been more-or-less cleared out, you can clean up the inside walls of the vessel with very light and careful passes until you reach the uniformity you want. Then, reverse chuck the piece in a vacuum or jam chuck to finish-turn the bottom.