Guild of New Hampshire Woodworkers
Ninth New England Woodturning Symposium
Saturday May 12, 2018
Pinkerton Academy in Derry, NH
Twice Turned Bowls
My process for turning a bowl is comprised of three steps: shaping most of the outside of the bowl, reversing the blank and hollowing the inside of the bowl followed by gripping the rim and completing the foot. The twice-turned bowl uses the same process—twice. Firstly, by using a wet wood blank to make a bowl with oversized wall thickness and allowing it to dry then secondly, remounting the dried blank in nearly the same position as it was originally, the bowl is completed.
In the second turning (of the dried, rough bowl) the blank has distorted during drying to an approximately oval, especially noticeable on the rim, the spigot has distorted as well. To return the rim and outside to round it is cut again, between centers. We use a jam chuck inside the bowl and tailstock to provide support. During this stage, the spigot is returned to a cylinder as well. This re-turned spigot is gripped in the chuck spinning the bowl on the same axis. With this grip, we shape the inside of the bowl and establish desired wall thickness. Lastly, the bowl will be gripped by the rim by one of a variety of techniques such as jam chuck (highly accurate), Longworth chuck (easily made) and Cole jaws (simplest) and the spigot will be converted into the foot.
We will discuss mounting techniques including faceplate, wormwood screw and between centers. Usually, I will demonstrate the between centers technique and show how to align the grain in the log for desired effect. The second mounting will be in the jaws of a chuck; in preparing for this, a spigot will have been created in the first step. From the second mount, the rim will be completed and the inside of the bowl removed. Lastly, the bowl will be gripped by the rim by one of a variety of techniques such as jam chuck (highly accurate), Longworth chuck (easily made) and Cole jaws (simplest) and the spigot will be converted into a foot. In each step, the surface will be scraped and sanded; in the last step, slight blending of the two surface finishes the bowl.
My approach relies on using sharp bowl gouges and scrapers. I use three gouges, each with a different knife angle. The most common is the swept back grind pioneered by David Ellsworth and contemporaries a few decades ago. In addition, I will show how a gouge with a steeper angle is very useful for the bottoms of the bowl and how one with a very shallow angle is convenient for platters and vases. We will compare conventional scrapers, negative rake scrapers and a scraper sharpened with a burr much like a card scraper.