Vladimir Schwartzmann: Turning Petal-rimmed Vessels

Over the past year Vladimir has been experimenting with goblets, bowls, and boxes with petal shaped segments surrounding the lip of the vessels. He has found his results improved as he developed better designs and cutting techniques. His technique involves cutting a number of oval shaped cross sections from round branches or laminated flat stock turned to a cylinder. When the round branches are cut at an angle the sections have an oval rather than circular shape. These oval elements are glued together in a flat ring much like a detail ring for segmented bowls. The flat ring is then glued to the flat top of a solid bowl blank. The assembly can then be turned into a profile such that the petals arch out as a flared rim at the top of the vessel.

Design Considerations

The branches chosen for the petal stock should be fairly round and not prone to splitting. A dense, close grained wood is preferable. If a natural edge effect is desired choose a wood that has stable bark that will not come off during turning. Very thin bark and very thick bark can be troublesome. Vladimir used maple branches with dark center heartwood and light outer sap wood. This produced light petals with dark centers for a very attractive effect that complimented the black walnut chosen for the vessel body. The number of petals needed will be a function of the diameter of the branch and the size of the vessel to be turned.

Preparing the Petals

Vladimir cuts his petal sections with a chop saw set to a 45°-50° angle to the axis of the branch. He uses a 2"×4" stop block with the end cut to the same angle desired for the cross cuts. This accomplishes two purposes:

a) When the angled face of the first cross cut is pressed against the beveled stop block it provides a bit of resistance to rotation of the round stock under the saw blade improving safety.

 

b) When the block is set the desired distance from the blade repeated cuts will produce sections of equal thickness. The petal thickness is dependent on how flat the rim is to be. A steeply sloped rim will require thicker petal sections that a flat rim.

Note that the width in the narrow dimension of an oval petal will be the same as the diameter of the branch or cylinder from which it is cut. If the vessel to be turned is to have a 10 inch circumference and the petals are cut from a 1 inch diameter branch it will take 10 petals to form a complete circle. Vladimir usually cuts one more petal than he thinks will be needed.

The inboard edges of each petal must be cut flat at an angle appropriate to create a circle with the petals laid edge to edge. The safest way to do this is on a disk sander. Vladimir dry fits the ring on a flat surface to verify the joints and the sequencing of the petals. When satisfied with the assembly he numbers each petal sequentially so the fit can be reconstructed when gluing. The petal ring is completed by applying glue to each of the flat edges and assembling them into the circle on a flat surface covered with paper. Take care to press each petal against its neighbor tightly to create narrow glue joints. Vladimir uses Titebond glue for this purpose. When the glue has dried completely the paper can be stripped from the bottom of the ring and the bottom surface of the ring sanded to remove paper and glue residues and to ensure that surface is truly flat. Vladimir does this on a belt sander.

Preparing the Base Blank

The base blank will become the body of the vessel. The blank can be mounted between centers or on a screw chuck. Turn the blank to a cylinder. Turn a tenon on the bottom face for future chucking purposes. True up the top face so it will be perfectly flat to receive the completed and cured petal ring. Be sure the center of the upper face is clearly marked to aid in centering the petal ring on the base blank.

Remove the base blank from the lathe and apply glue to the flat upper face. Place the petal ring on the glued area of the upper face of the blank. Take some care to ensure that the petal ring and the base blank are concentric. If the petal ring is slightly off center the rim will not be symmetrical. However, this might not be very disturbing if the petals create a natural edge. Let the glued assembly dry thoroughly before continuing with the turning steps.

Turning the Vessel

The bottom surface of the rim and vessel is the first area to be turned. Mount the combined base and petal blank on the lathe either between centers or with a screw chuck so that the bottom face will be fully accessible. Vladimir used a ½ inch bowl gouge to shape this lower surface. He used light bevel cuts with the grain (large diameter toward small diameter) to create the bottom profile of the petals and the cove where the rim transitions into the body of the vessel. When the shape was established he used a round-nosed scraper to refine the surface of the cove and a negative-rake radiused scraper to refine the surface of the petals. He then used the bowl gouge to make a combination of bevel cuts and shear scrapes (small diameter toward large diameter) to shape the outer profile of the vessel body and fare it into the junction with the petals. The surface of the body was refined with the negative-rake scraper. This shaping process was done without disturbing the tenon on the bottom face of the body. Vladimir hand sanded the bottom surface of the petals and the upper section of the vessel body with the lathe turning.

The partially turned vessel can now be removed from the lathe and reversed with the tenon in a scroll chuck. This makes the upper (or inner) surface of the vessel accessible. To ensure stability, the upper surface of the petal rim was cut and sanded before removing the bulk of the vessel interior. The outer half of the petals was cut first and then the inner half. This upper face parallels the shape of the lower face to a thickness that is appropriate to the intended wall thickness of the vessel. It is important to use light cuts while shaping the petal rim. The final shape and surface can be refined with the negative-rake scraper and hand sanded. The interior of the vessel can then be hollowed just as you would with any other type of vessel. Vladimir used the same tools on this surface that he used on the bottom surface except that he used a Forstner-type bit to bore a starting hole. He also demonstrated how he sometimes uses a wood-slicer tool to remove a cone from the center of the interior to begin the hollowing. Vladimir likes to create a feature on the interior that will allow the piece to be rechucked again to finish turning the exterior bottom, e.g., removing the tenon and creating a foot. In this demo he undercut the upper wall of the vessel so he could create a jam chuck or use an expansion grip with Cole jaws for that final step. Vladimir refined the bottom of the interior with the round-nosed scraper and then sanded with the lathe turning.

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