Three ways to turn a bowl: February 23, 2013
Harry Newman, Cliff Baker, and Mike Cope demonstrated the ways they mount blanks on the lathe and how nthey use their preferred tools to turn natural-edged bowls.
Harry Newman: Using a Faceplate and Scrapers
Harry uses a scraper made by the Hawaian woodturner Stewart Madeiros. The scraper is made from 1/4" thick knife steel and is fitted with a long handle. The knife steel holds an edge very well and the scraper can be used very aggresively when it is flat on the tool rest or can be used on edge as a shear scraper to remove fine shavings and produce a smooth surface.
He normally uses a faceplate for mounting all his bowls. Even though it provides the safest attachment to the lathe, he always uses the tailstock live center to provide additional support. The fact that the faceplate determines the plane of the rim is a real challenge, plus it is necessary to deal with the screw holes when the foot is finished.
Since tha tool handle is quite long, Harry can hold it against his body so he can easily control the tool and remove large amounts of wood very quickly. Keeping the tool rest close to the workpiece helps achieve a smooth surface but since the scraper is very sturdy, it can safely extend beyond the tool rest. He takes very light finishing cuts in order to minimize sanding.
Harry frequently turns bowls from green wood in which case he will rough turn the bowl with a wall thickness that is about 10% of the bowl diameter. He coats the entire bowl with end grin sealer, dates it, and puts it on a shelf in his shop and lets it dry for up to a year. When it is thoroughly dry, he will mount it on the lathe and turn the inner and outer surfaces to the desired thickness. After the bowl has been sanded, he applies the final finish.
Cliff Baker: Using a Pin Chuck and Bowl Gouges
Cliff prefers to use standard bowl gouges. The 5/8" gouge shown here is ground with a bevel angle of 40 degrees and a relatively short fingernail grind. Final cuts are made with a 3/8" gouge ground at 50 degrees cut further towards the center of the bowl and still "ride the bevel".
A friend machined a 1 3/8" pin chuck for Cliff. The blank is set on a drill press table, moved to locate the center of the bowl in the desired position, and tilted as necessary so the rim will have a pleasing profile. A hole is drilled and the pin chuck inserted. A piece of a nail keeps the blank from spinning on the pin. The tailstock is always used to stabilize and support the blank.
Cliff turns the outside profile using push cuts with the 5/8" gouge to quickly establish the profile of the bowl. A 3/8" bowl gouge is used to make the final finishing cut. A dovetail tenon is cut on the base and a 4-jaw chuck is used when the inside is turned. The 50 degree 3/8" gouge allows cutting closer to the center. For deep bowls, a scraper must be used to finish shaping the bottom.
Once the bowl has been rough turned, Cliff allows it to dry before sanding and finishing it. If the wood was very green, he wraps it in newspaper, puts it in a cardbard carton stuffed with newspaper, and lets it dry for a week. After that, he unwraps it and lets it stay indoors until it is dry. Drying is monitored by weighing the bowl on a kitchen scale, marking the date and weight on the bottom, and weighs it every few days until the weight stabilizes. A recent bowl had a stable weigh after loosing 25% of its wet weight after 2 weeks. The bowl is then mounted on the lathe and the inside and upper portion of the outside are power sanded to 400 grit. The bowl is mounted on a vacuum chuck, the tenon is removed, the foot is turned to its final profile, and the sanding is completed. Cliff normally finishes his bowls with several coats of pure tung oil, a food-safe finish, followed by paste wax.
Mike Cope: Using a Spur Drive and the Ellsworth Gouge
Mike uses a gouge with the Ellsworth grind so he can take both rough and finish cuts with the same tool. Unlike conventional gouges, the bevel does not contact the wood when cutting the outside of the bowl. With the Ellsworth grind, a finishing cut on the interior of the bowl can easily be made from the rim to the bottom.
Mike often turns natural edge bowls between centers. He positions the spur center on the top surface of the blank and drives it firmly into the wood. After the blank and spur center have been mounted on the headstock, Mike adjusts the position of the live center to align the rim and firmly tightens the tailstock.
A unique feature of the Elsworth grind is that when the exterior of the bowl is being turned, the bevel does not contact the wood. However, the bevel does rub on the wood when the rough interior cuts are made. Heavy cuts are taken from the center to the rim, but when the finish cut is made, the shape of the cutting tip allows a single cut be made from the rim to the bottom of the bowl.
The Ellsworth grind is very different from conventional gouge grinds in that the shape of the tip is parabolic and the wings are ground so they sweep back about 3/4". As noted, the bevel does not contact the wood when exterior cuts are made. Heavy cuts are made with the upper edge of the tool while finishing shear cuts are made with the lower edge. When roughing cuts are made on the interior, the right edge of the tool is used for cutting, and the bevel is not in contact with the wood. The finish cut is made from the rim to the center with the flute up, the left bevel contacting the wood, and taking a light cut with the left edge of the tool.
When turning green wood, Mike usually turns to final dimension and sands to a final grit of 1000. As the piece dries it will warp and add interest to the piece. Burl wood also gains a ropey texture which adds interest to the piece. The final finish of Salad Bowl Finish and Beal Buffing are applied after the piece is dry.
Jim Meyer explained how he made this intriguing wooden puzzle. He started with a piece of spruce 2x4 and cut the fingers on his table saw. He then boiled the end of the block for several hours to soften the wood and tightened a clamp on then last finger to compress it to about half height. After it dried for a couple of days, he removed the clamp, drilled a hole through the five fingers and inserted the nail. After that, he boiled the block again so the finger would expand to its original height. After drying for a few days, he sanded all surfaces of the block so all fingers were identical.
by WVWA, a chapter of the American Association of WoodturnersReturn to the Events page