Article: David Ellsworth Demonstration June 2012
July 25, 2012 16:13, submitted by Tina Collison (author: Bob Gunther, photos by Tina Collison)
June 16, 2012 Demonstration with David Ellsworth
David first used a lathe in a workshop class in 1958. He continued to turn throughout high school. He then spent three years in the military and eight years in college. He studied architecture, drawing, and sculpturing. He received a master’s degree in fine arts from the University of Colorado in 1973. He started the woodworking program at the Anderson Ranch Arts Center in Snowmass, Colorado in 1974 and the following year opened his first private woodturning studio in Boulder, Colorado.
It was during the mid-1970s that David developed a series of bent turning tools and methods required for making thin-walled hollow forms for which he has worldwide fame. His first article, “Hollow Turning” appeared in the May/June 1979 issue of Fine Woodworking magazine. Fox Chapel publishing released his first book, "Ellsworth on Woodturning", in 2008.
David is a founding member of the AAW. He was its first president (1986-1991) and its first Honorary Lifetime Member. He authored more than 50 articles on subjects related to craft and woodturning and opened the Ellsworth School of Woodturning at his home and studio in Quakertown, PA in 1990.
His work is featured in 35 museums. In 2009 he was elected the “Master of the Medium” by the James A. Renwick Alliance of the Smithsonian Institute in Washington, D.C. He is an Honorary Lifetime Member of the Collectors of Wood Art. He demonstrated for CMW in 2002 and 2008 and he taught CMW classes as recently as June 15, 2012 in our TLC.
David began the session by turning an open bowl of ash. He placed the one-half log piece with the corners removed between centers (live center/spur center) with the bark surface at the tailstock end. He set the tool rest so that the tool cutting edge was on center. David balanced the piece between centers so that the lathe would not vibrate when turning and he set rest at an angle to the wood instead of parallel to the ways.
He began with a roughing cut using his signature swept-back bowl gouge in the horizontal position and with the line across the edges of the flute at 45 degrees. This puts all the pressure of the cut directly into the tool rest instead of the turner.
He removed the corners of his piece first. David did this in a step-wise fashion so that he wasn’t beaten to death as the corners came around to the gouge on each lathe revolution. The bevel was not rubbed. He then used a slicing cut by lowering the tool handle approximately 30 degrees. This produced a cleaner surface because the tool cut the fibers and did not rip them. This slicing cut rapidly roughed the shape of the piece. Now with the two pith areas on each side of the piece visible, David adjusted the piece so that the pith line was perpendicular to the lathe bed. He achieved this by slightly moving the tailstock live center location. Once adjusted David returned the piece and formed a tenon on the tailstock end to accommodate the jaws of the chuck. He turned a second foot (base cut) above the jaw tenon. This aids in the final shaping of the piece so that the turner has complete freedom as to the location and diameter of the foot of the bowl.
David removed the piece from between centers and placed it on the chuck. The final foot or base of the bowl will be smaller than the tenon. Therefore, David uses a larger diameter set of jaws in a large chuck, not the typical #2 jaws. This larger tenon and jaws also support the piece, especially when using wet wood. Small tenons can easily tear out of the jaws with too much pressure against the wood during a cut, or if a catch occurs. He brought up the tailstock for safety. Then David established the edge of the bowl about 3/4 inch below the pith. This decreases cracking and distortion during the drying process. He used the swept back side of the gouge to aggressively remove wood in the slicing position. David placed the gouge with the handle against his right hip and used his left hand to hold it on the tool rest. The tool rest takes most of the pressure of the cut. David’s body moved with the gouge as he made the cut. This allows the energy for the cut to come from the abdomen and decreases stress on the shoulders and arms.
David shaped the outer surface of the bowl using the slicing cut. When looking at the shape of the bowl, the outer surface goes into the bottom inside the jaws so that the jaws do not enter the final shape of the foot. He took the gouge to the grinder and freshened up the cutting edge in preparation for the shear-scraping cut to refine and finish the outer surface of the piece. David uses this cut going from the rim to the base. This eliminates any torn fibers and ridges. The edge of the rim was slightly rounded to be more user-friendly. It would then be sanded. David uses Abranet paper.
Then David hollowed the bowl using roughing cuts toward the center to remove the bulk of the wood. He moved the tool rest into the piece so that the tool would not be too far over the rest. David then uses a finishing cut going from rim to base, but now using a tiny portion of the left side of the tool while supported by the bevel. This is the only cut of the five primary cuts that relies on using the bevel. It is critical that the flute is pointed straight up so that the gouge is level. Even a two-degree change in angle can cause the long swept back wing to contact the wood and cause a dramatic catch. He used this finishing cut all the way to the bottom. To avoid leaving a nib in the bottom of the vessel, David simply slowed the cut down when entering the center and rode the bevel through the nib. In a deep bowl, it is possible to use a gouge with an 85 degree bevel to turn the transition area between the upper bowl wall and the bottom. Sanding would now be done.
David removed the bowl from the jaws and placed a jam chuck on the headstock. He placed a half-inch thick foam rubber sheet inside the piece before placing it on the jam chuck. Then he brought up the tailstock and centered it on the previously marked center. Then David shaped the outer surface taking into consideration where the bowl bottom is. He used backward slicing and shear-scraping cuts to finalize the shape, thus cutting downhill toward the foot. He made a small radius around the bottom edge as he did on the rim. Using a 3/8 inch spindle gouge to undercut the base, David tapered the remaining stem on the bottom of the piece. He removed it from the jam chuck and removed the remaining stem on the bottom. This completed the open bowl.
Next David rapidly turned a natural edge bowl (start to finish in less than 18 minutes). Again, he placed a half log of ash between centers with the top of the bowl placed into the spur center. It was rapidly rough turned. Jim Nunziato’s “William Tell Overture” accompanied the turning. He formed the natural edge and made a tenon on the tailstock side. He removed the piece from between centers and placed it in the jaws. To save the natural edge from tearing, David made the cut into it from the rim down toward the base of the bowl with the slicing cut. Then he hollowed the piece using the roughing cut. He used a shear scrape to complete the surface. David roughed out the inside to 1/4 inch thick. Using the finishing cut, and to avoid cutting the edge thicker than the rest of the vessel wall, he lined up the bevel on the left side of the gouge parallel with the outside edge and the proper wall thickness away. Thus, when making the cut, the wall thickness is the same at the edge as farther down the wall. He made a final finishing cut. To measure the depth of the bowl, David used the wing tips as a guide. Then he reversed the piece and placed it on the jam chuck and finished the base finished as he did earlier in the open bowl. This completed the morning session.
David began the afternoon session by placing a 12” long ash log section between centers using a live center and a spur drive. First, he balanced the piece by adjusting the centers so that the lathe would not vibrate. He shaped a cylinder form by removing the bark, then he cut it into a sphere-like shape by paring down both ends. Then David turned it 90 degrees so that the grain was now crosswise to the bed of the lathe, and trimmed it to true sphere. He drew a pencil line around the center, then removed the piece from between centers. He placed the spur and live centers on the pencil line and centered the piece. David turned away the two spigots left from the previous axis turning and turned the entire piece to cut off the ghost images as the piece turned. Again, he balanced the piece again so the pith went through the center of the piece and not off to one side. Thus, when finished, the pith line will be parallel to the foot of the vessel.
David flattened the tailstock end of the “sphere” and made a tenon and a base cut (as he did on the two bowls turned during the morning session). He removed the piece from between centers and placed it in the chuck. He brought the tailstock up for additional support. He flattened the tailstock end (where the opening of the vessel will be) and rough shaped the piece little by little until he achieved the desired shape.
David cleaned up the surface up using a slicing cut and then the shear-scrape going from the larger to smaller diameters at each end. He does not hone because he needs the burr for the shear-scraping cut. David sands the outside of the vessel before the hollowing process starts. He slightly rolled the top edge of the piece. Then David applied stretch wrap to the piece to prevent evaporation and drying, especially in the areas of the piths. He hollowed using his standard straight and bent tools. He did the interior of the piece in stages, progressing from the opening to the bottom. Once he hollowed an area to the desired thickness he does not return to that area. Please refer to the included photo of David’s step by step process. ST= Straight B – Bent.
David set the tool rest at 40 degrees across the face to give support for the heel of the left hand when holding the tool, and so that the tool’s cutting tip is on center. First, he used the straight tool going from left of center to center, thus opening up the piece. David began with area #1 and progressed to #2. The compressor helped to remove shavings as they built up. Hollowing progressed through #3, 4, 5, 6, 7, 8 and 9.
He removed the nib left in the center of the bottom with the straight tool by locating the nib, dropping below it, going up to the center, then to the left and back to the center. By this point, the nub should be gone. If not, repeat the process. David checked wall thickness with a caliper made from a 3/16 inch unthreaded (zinc plated) rod that is usually available at Lowe’s or Home Depot in 36 inch lengths. The two tips of the bent rod need to be at 90 degrees to the vessel wall when making determinations. Because of this, the two tips of the caliper are bent so they are offset instead of parallel, thus allowing one to measure wall thickness in the upper area of the vessel, then flip it upside down to measure in the lower areas.
David removed the vessel from the chuck and reversed it onto the jam chuck. He balanced it to run true. He scribed the level of the bottom of the interior of the vessel on the outside and added 1/4 inch for wall thickness and another 1/4 inch for the base thickness. He used light cuts to form the outside surface of the base of the vessel because the nub on the live center was small and therefore not very strong. Using a detail (spindle) David undercut the base of the piece and narrowed the diameter of the nub. He twisted it off completing the piece. Normally, David places his pieces in a paper sack to dry over time. He adds no shavings to the sack.
David then turned to grinding, stressing that one only needs to “dress the bevel”, not “sharpen the edge.” As such, the edge will form naturally. It should be done gently. One should not be too aggressive when using a grinding jig or it is possible to do some serious damage to one’s hand and fingers. To sharpen the gouge used for the deeper transitional areas of the vessel interior, use the plate on the grinder and simply sharpen as one would a roughing gouge. The plate should be set at a little less than 90 degrees.
To dress the hollowing tools David formed a small radius on the corners of the grinding wheel. The tool is slightly ground on each side to the tip giving an even radius both sides of the tool tip. To practice with the hollowing tools, use them to do an open bowl (small) where it is possible to see the cuts.
This completed an excellent and enjoyable demo. A DVD will be available in the club library in July, 2012.