A Split-Turned Rocking Vessel
Joinery, joining parts to make a whole piece, is an “additive” process. Woodturning, on the other hand, involves taking a whole piece and removing the unwanted bits to create the final piece; a “subtractive” process. Making split-turned objects is a perfect blend of both processes. It’s a wonderful way to develop creative skills by considering both inner and outer shapes harmoniously to suit your style and the piece’s purpose. Split turnings are also a great way to use grain and figure for visual effect and add a distinctive dimension to your work.
I began exploring “split turning” in the late 1990s, inspired by Stephen Hogbins’ “Walking Bowl” of the ’80s and by Michael Hosaluk and Mark Sfirri, who were demonstrating both split and multi-axis spindle forms of turning, encouraging others to take the style to new levels of decorative and functional expression.
Split-turned elements are seen in furniture pedestals, legs and case corners plus in architectural fixtures such as columns, newel posts, wall sconces or demi-lune shelves. But here I’ll explore the vessel form, creating display pieces that are both attractive and functional. Fun and way easier to make than it may appear, follow along as a simple bowl transforms into a dynamic vessel form … once you’ve tried it, you won’t quit by making just one.
Rough and Ready
The rough bowl form is mounted in the chuck, ready for turning. It’s supported by the tailstock with live center (within the bowl and unseen).
The three phases of completing the bowl; the rough form (left), turned inside and out (middle) and the completed profile with the foot removed (right). Shown also are my inertia sander resting on the toolrest post and my large chuck (background), used to hold the bowl by its rim when turning the foot away and refining the outer profile.
The bowl showing the rim, inner surface and the greater diameter of the bowl, which will be the vessel's “rockers”.
Time to Split
A simple jig assists with splitting the turning in two. While cutting, my thumbs advance the sled while my fingers dampen vibration.
Seeing is Believing
With the bowl now split in two, you will learn how consistent your wall thickness really is. You can also finally see how the bowl looks when the two halves are re-aligned and come together to form a new shape.
Add Masking Tape
The tape aligns the two vessel halves and acts like a hinge, allowing you to apply the epoxy adhesive and bring everything together.
Cupping the Bowl
The vessel temporarily goes back to being a bowl as the epoxy is applied to one of the rim halves. The coffee can cradles the parts, adding an extra set of hands during this careful process.
This is all the squeeze-out I want. Any more and it makes clean-up that much more difficult. The tape draws the halves together, while additional strips apply extra pressure where needed.
Flatten the Rim
Sand the vessels rim flat to remove the fine bandsaw cut marks. Rubberized gloves make life easy, providing grip and control.
I’ve found the easiest way to get “into the groove” is to take some practice wood, turn a flat-rimmed bowl, flip it upside-down and cut it exactly in half on the band-saw to reveal what form is made when the rim edges are held together. From there, I refine my thoughts, consider the purpose of the vessel, consult my sense of style and make a quick pencil sketch of the shape I want to see outlined by the rim of the finished vessel; one half of that will be the cross-section of my bowl. Seldom a perfect drawing, it’s just enough to show the length, width and internal volume of the piece I see in my mind’s eye. It helps me see the relationships of shapes and decide on defining details plus the diameter and depth to turn the bowl. I also use this time to think about the placement of the bowl’s greatest diameter, upon which the final vessel will rest, choosing how much stability is best for each vessel I make. A few quick thoughts with a relaxed mind then it’s on to the fun stuff.
With the O.D. of the bowl decided, it’s time to make the foundation of all future pieces, a cutting sled. My sled, of 3/4″ cabinet-grade veneer core plywood, is exactly 10″ wide and about twice as long, with a 10″ long kerf cut exactly on the centerline; all the bowls I’ll be halving will be less than 10″ in diameter. A brace, milled straight and square, is glued across the sled behind the saw kerf for stiffness and a hand grip. The side supports that cradle the work-piece are glued at exactly 45˚ to the saw kerf, 90˚ to each other. By guiding this precision jig between a fence and a feather block, its kerf centered on a sharp blade with the saw table set exactly 90˚ to the blade, I’m assured my vessel halves will be perfectly equal and need minimal sanding to perfect the vessel’s rim after glue-up.
Now to the lathe …
The vessels shown here began as blanks I cut roughly twice as round as they were tall, including the allowance for a proud foot; 10″ x 5″ for example. I used figured maple here, but these vessels are just as satisfying turned from any clear hardwood.
I like the dynamic created between the concave inner shape and the convex outer form. With that in mind, I cleanly turn the bowl’s outer profile and a stout protruding foot for my chuck to compress onto. Next, I reverse the piece, centering it within my chuck’s jaws and with the piece supported by the tailstock and live center, I refine the outer profile and flatten the top to bring the piece into round and almost fully balanced.
With the tailstock removed, I decide on the bowl’s inner diameter. I like something over half the bowl’s O.D. The greater the inner diameter at the rim, the more relaxed the look and functional the final vessel will be. But too large and the vessel will suffer visually. Now I turn the inner shape, undercutting from the rim down, going deeper and wider in stages. I try to follow the outer profile as much as possible, smoothly and uniformly, leaving a reasonable wall thickness, say 5/16″ for a piece of this size, right down to the footed area. The foot will be turned away later and the wall thickness and smooth internal profile referenced when completing the final profile.
With the piece now fully balanced and main wall thickness measured, I mark that dimension surrounding the rims inner diameter and proceed to remove material outside that line, downward and outward, roughing out what will be the “rocking” rims the vessel will rest on. I like a spacing of about 2″ between the vessel’s “rockers”, so I make the bowl’s greatest diameter just over an inch down from the upper rim. I also like an outer profile here that complements the inner form. Here’s where continuity, the profiles and detailing will set the tone for the final piece, geometric or organic, once the halves are reunited. With this area shaped and detailed, it’s important to make the top surface of the rim perfectly flat across; this will be the gluing surface to unite the two halves. I gently scrape this surface to perfect it and, with the lathe stopped, check it by bridging a straightedge across the rim.
Next, I power-sand the outer and inner surfaces to 180 grit then do my final sanding using an inertia sander and a 240 grit disc, leaving a uniformly sanded, swirl-mark free surface. I make sure not to round over any edges, keeping them crisp and I leave the rim just as I scraped it.
Now I release, reverse and rechuck the bowl, expanding firmly yet gently within the rim (there are many ways to do this so choose your preferred chucking method) as it’s time to gently turn the foot away, blend the outer profile and sand the entire outer surface to perfection.
Split the turning
Over at the workbench, I set the finished bowl upside down, resting flat on its rim between the left and right guide shoulders on the cutting sled. Looking down on the bowl, I orient it so that the wood’s grain and figure are centered along the kerf; once it’s cut and reunited, the vessel will appear book-matched. I apply 3/4″ wide painter’s tape and stretch it to hold the bowl in position on the sled.
At the bandsaw, I cut the bowl slowly, my hand advancing the sled and my finger tips merely damping vibration the bowl may experience, minimizing any tear-out by letting the blade both cut and burnish the kerf. Once the blade is stopped again, I remove both halves from the sled, de-fuzz the cut edges by sanding them gently up and away using a hand held 240-grit sanding disc and remove all dust from the cut surfaces.
The moment of truth
I hold the two halves together rim-to-rim, inspecting for consistency and alignment. Satisfied, I invert the vessel halves, held edge-to-edge onto a thin router mat on my bench to keep things from moving. Strips of 2″ wide painters tape are laid face down onto the mat and the cut surfaces of the vessel placed onto the tape’s sticky side. Once stretched a little and wrapped around the sides of each half, the tape forms a hinge registering the halves in alignment. Now I gently fold the vessel open to return the halves to “bowl” form, nest the bowl halves together within the rim of a coffee can or other clean, supportive container and apply an oh-so-thin veneer of epoxy adhesive to one rim surface only. Epoxy offers longer working time, better bond and an invisible glue line compared to wood glues and requires little clamping for strength.
Now I carefully lift and invert the two halves again, using the tape hinge for reference and to draw the halves together, placing the glue-up down flat on the mat. Checking alignment as I work, I stretch tape across the bottom of the two halves; first bridging the center then across each side edge. Properly done, a slight uniform squeeze-out appears along the entire glue line and the two halves are perfectly aligned edge-to-edge and along the length. After the assembly has set face down for about an hour on a flat surface, Q-tips dampened slightly with lacquer thinner will remove any squeeze-out, but I’m careful not to wet the glue line and weaken the joint.
After 24 hours, I remove the tape and sand the saw-cut rim of my vessel on a sheet of 120 grit paper taped down to a flat piece of plywood or MDF, sanding in a random pattern until all traces of the bandsawn surface are gone. Then I sand the rim by hand using a back-up pad and hook-and-loop backed discs, 180 then 240 grits, softening the rim and all edges so the piece is as friendly to hold as it is pleasant to look at.
I enjoy Danish oil or a wiping varnish as finishes, applied generously, hand-sanded while wet with +400 grit wet/dry paper or sanding discs then removed thoroughly within a few minutes. After a few such applications have cured fully, a final coat of varnish can be ragged on and off, left to cure overnight then buffed out with wax applied with oil-free 0000 steel wool or an ultra-fine micro-fibre pad and buffed to a soft sheen.
But don’t stop there – the creative potential has just started! Gold leaf, carving, texturing, cutting the vessel in half cross-wise and reassembling it another way … all will produce wonderful work. Have fun exploring.