Turning a Winged Bowl
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Below, is a photo tutorial of the basics of the process of turning a winged bowl . . . if you've never tried and have questions, just give me a ring . . . I thought this piece of burl might be exceptional and I was not disappointed . . . it's perhaps the most stunning piece of burl I've seen to date . . . in my opinion, puts amboyna to shame. As for the turning itself, that's for you to judge.
I use 1-1/2 self-tapping screws and drill directly into the wood (no pilot hole required). This piece was 27x22x5 to start, so I chose to use a 8" face plate and 12 screws . . .
Below . . . I start by removing "high spots" on the exterior face of the burl before defining the wings and a tenon
Below . . . when I define the wings, I ride the bevel, and take small cuts to try to avoid tear out (careful not to "push" into the wings) . . . I maintain a wide base with my feet and move my body as I cut from the outside edge in . . .
Below . . . before reversing and chucking, I true up the top face, roughly define the bead and edge of the bowl . . .
Below . . . when the wings have been defined and I have a clean surface, I turn the gouge over and perform repetitive shear scrapes from outside in to get a really clean surface (and minimize sanding)
Again, note the wide base of my feet for stability and the position of my left hand (tucked into my body) and right index finger (supporting the tip up the gouge . . . DO NOT push in . . . if you have to apply pressure to get your gouge to cut, it's not sharp enough) . . . I take repeated light cuts until I'm satisfied with the surface . . . note the very fine shavings below . . . these are all techniques I learned in David Ellsworth's class . . .
Before removing the face plate I chuck the piece and verify that it rotates true . . . doing so allows me to slightly adjust the tenon and bearing surface in case it's not quite true . . .
Here's the real fun . . . reverse turning using a vacuum chuck system and spinning a 27" burl at 400-500 rpm . . . my goal is to have at least 18 in Hg (I had almost 20 here) . . . if you have trouble getting sufficient vacuum because of microcracks and/or barely visible fissures (I'm not talking Jarrah Burl here), try rubbing some of your shavings along the exterior of the bowl and watch your gauge
Below . . . look Mom, no hands! The challenge here was getting the burl perfectly centered without the aid of a tail stock and live center . . . the completed (unfinished) piece . . . for this particular piece, I coated with clear/natural Danish oil, let it soak in, then wiped off and allowed to dry for a few days before applying a coat of Waterlox Original Sealer, followed by Waterlox Original Satin, followed by a final light coat of Waterlox Original Sealer (brushed on) . . . if you get brush marks, you can either buff out (I recommend only the tripoli wheel to avoid filling microcracks with white diamond residue) or sand with 800/1200 grit paper (after drying for several days), blow out with compressed air, and polish with a wax such as Mylands.