Multi-axis BowlComments (0)
Several issues ago, we published a photo of some small ash bowls I had made with off-center cavities embellished with a series of small beads (inset, right). As I was revisiting this design, I wondered what would happen if I hollowed a bowl using more than one off-center point. After playing with the technique, I arrived at the bowl presented here. It features a three-lobed cavity, decorative beads, and a two-color, dyed finish. Overall, the piece is radially symmetric in the tradition of “regular” bowl turning, but using three different center points to turn the interior creates three intersecting ridges that give the bowl a unique look. I purposefully kept the overall diameter small so this project could be made on a midi-lathe. However, off-center turning can involve a fair amount of vibration, so be sure to have your lathe mounted securely, perhaps with added weight. The bowl here is made from kiln-dried 10/4 curly maple. Using kiln-dried material allows you to complete the bowl in a single session without it distorting and with minimal risk of checking. Feel free to substitute your favorite stock, but if you intend to use dyes for coloration, light-colored woods such as maple or ash are a better choice, as they provide more contrast.
Three center points yield three lobes
The 7"-diameter blank was cut from a dressed piece of kiln-dried, 10/4 stock. The outside profile is turned as you would a normal bowl. However, the interior cavity consists of three “lobes,” each turned on a separate axis to create intersecting ridges. The profiles shown here match the piece in the photos, but you needn’t follow them obsessively. As with most turning, close is usually good enough. As for the overall shape, I advise sticking to a “soup bowl” profile as the interior lobes will have concave contours which lend themselves well to easy smoothing with a bulb sander.
A center-finding faceplate
Most faceplates have a large center hole. This project requires one with a small hole. If you don’t have the latter, you can adapt the former to suit. Start by adhering a disk of 1⁄8" plywood to any faceplate using double-faced tape. Turn it to match the plate diameter, then drill a 5⁄32"-diameter hole through the center with a brad point bit in a lathe-mounted drill chuck. Also drill through the workpiece-mounting holes before using the faceplate as usual.
Prep the blank and turn the outside
Lay out a 7"-diameter blank on 10/4 stock, marking the center point on each face of the blank before bandsawing it round. Cut a 1"-thick mounting block that is about 1/4" larger in diameter than your faceplate, and glue it to what will become the bowl’s bottom. On the opposite face of the blank, center and attach the faceplate using 1-1/2" screws, and mount to your lathe. Trim the mounting block and mark its center. Then true the outside of the bowl blank before turning it to shape. Unscrew the faceplate, reverse the bowl, and attach the faceplate to the mounting block, centering it carefully. Then turn the rim to shape. If you didn’t get the blank perfectly recentered, touch up the outside before sanding through 400 grit.
Attach the mounting block. Mark the mounting block’s diameter on the blank and squeeze a bead of thick CA glue around the inside of the line. Spray the mounting block with CA accelerant and press it in place for a few seconds.
Shape the outside. Trim the mounting block to match your faceplate diameter, mark its center, and shape the outside of the bowl with a bowl gouge. Rub the bevel and cut from the block towards the rim for the smoothest surface.
Shape the rim. With the bowl reversed, use a bowl gouge to shape the outer rim and about 11⁄2" of the interior surface. For the rim, cut from the outside inward. For the interior surface, cut from the smaller diameter outward.
Detail and dye the outside
To finish turning the outside, cut in the two detail lines near the rim and wire-burn them as an accent. These lines serve not only as decoration, but also as a border for the dye. Apply the dye with a rag and/or cotton swab. I used TransTint green diluted in alcohol.
Cut in the lines. To create guide channels for the burning wire, use a spindle gouge to make two cuts just below the rim.
Follow up with friction. To burn in the lines, lodge a taut burning-wire in the cuts and run the lathe at 1200-1500 rpm while applying firm downward pressure.
A splash of color. Don gloves and apply dye to the bowl’s rim. I used a rag for most of the application, then switched to a swab to work up to the upper burned line.
Turn the cavity
Here’s where this project departs from turning as usual. Start by laying out the three off-center points on the mounting block. Screw the faceplate to the block, centering it on one of these points and remount to your lathe. Then mark and turn the first lobe. (Although you could also sand this first lobe on the lathe, it’s better to smooth the entire interior at the drill press as shown to ensure similar surfaces.) Repeat the process to turn the other two lobes. Try to keep them the same shape, which will make the cavities’ dividing ridges straight.
Off-center layout. Use a 60° triangle to lay out a center line and two additional, equally-spaced radial lines. Then, mark a 7⁄8"-diameter circle centered on the mounting block. Where the circle and radial lines meet are your off-center points for remounting the faceplate
Reattach the face plate. Center the face plate on one of the off-center points, and screw it to the mounting block. If you don’t have a faceplate with a small mounting hole as the one shown here, make your own as described on page 47.
Mark and turn the first lobe. Pencil in the perimeter of the first lobe, locating it about 1⁄4" in from the rim. Then shape it with a bowl gouge, cutting from the rim inward towards the center. Adjust your lathe speed to just below excessive vibration.
Turn the remaining lobes. Remount the faceplate, having targeted the next off-center point, then mark and turn the next lobe as before. This time it will be harder to read the shape, as you’ll be turning air as well as wood, so stop frequently to check your progress. Repeat for the third lobe.
Make the beads and finish up
After turning the bowl, drill holes in its rim for the beads where shown, and sand the interior. The beads have integral tenons that fit the drilled holes. To make the bead stock, turn a 4" length of 3/4"-square stock to a 5/8"-diameter cylinder. Then turn a 1-3/4" diameter by 2" long cylindrical jam chuck from a hard, dense wood such as maple. Grip this in your four-jaw chuck and drill a 5/8"-diameter hole through its center. Insert the bead stock in the hole, leaving an inch or two exposed, and lock it in place with a screw driven through the side of the jam chuck. Turn your first bead, part it off, advance the stock, and turn another. Repeat for the third bead. Then glue them in place before finishing the bowl. I used aerosol lacquer on mine.
Drill the rim. Cut a wedge to hold the bowl’s rim level on the drill press. Bore a 3⁄16"-diameter hole in the rim aligned with each of the three interior ridges.
Sand the interior. Sand all three lobes with a bulb sander chucked in the drill press. If your interior ridges are a little wonky, use the sander to help straighten them out
Turn the beads. With bead stock captured in a shop-made jam chuck, turn each bead to shape with a spindle gouge, and then part it off. Support the outer end with a live center until you’re nearly done.
Install the beads. Tap the beads into their holes with a small mallet or hammer, protecting them with a bit of scrap.
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