Hollow Turned VesselComments (0)
This article is from Issue 42 of Woodcraft Magazine.
An uncompromising cheat makes a tricky job easy.
Dimensions: 5" dia. × 63⁄4"h
A hollow turned vessel can be a real piece of art. Well executed, it’s not only a visual treat, but a wonder of workmanship since many people can’t imagine how you can excavate a thin-walled piece through a small hole at one end. But that is how it’s usually done, using special long-shank offset turning tools and a deft touch. The biggest challenge with this approach lies in maintaining the control of cut while reaching deeply into a blind hole. To help students ease into the techniques involved, I’ve developed a sort of “cheat” that simplifies the process.
In a nutshell, my technique involves first hollowing out just the top section of a vessel using an offset scraper. I then part off that section, which allows easy access for hollowing the remainder of the vessel with regular gouges and scrapers. Afterward, I reattach the top and add a decorative bead to conceal the joint line (Figure 1). The “split-top” is a great way to get started at turning hollow vessels, while producing a piece that will wow your friends and family.
Tools, Centers, and Chucks
You’ll need a basic complement of turning tools, many of which you may already have (Photo A).
Refer to the Convenience-Plus Buying Guide on page 49 for the three less common tools shown here, which include the straight-bodied scraper (Ci3 Easy Finisher), offset scraper (Ci3 Easy Hollower), and 1⁄16" parting tool. You don’t necessarily need all these specific tools, and I’ll note when you can use an alternative.
For this project, you’ll also need a 4-jaw chuck, a cup, or safety center, and a cone center. If you don’t have a commercial cone center, it’s easy to make one for this job, as shown in Figure 2. (Note: Unless you have another lathe, you’ll need to make the cone center before beginning work on the vessel.)
Shape the vessel’s outside
1 Bandsaw the turning blank to a rough 51⁄4"-dia. cylinder (Photo B), and then locate the center point on each end. (Note: The 93⁄4"-long blank shown here provides enough excess length to allow working at a safe distance from the chuck. If you’re comfortable turning adjacent to a spinning chuck, you can begin with a blank as short as 8".)
2 Mount the blank on your lathe between a cup, or safety, center in the headstock and a live center in the tailstock. Turn the blank to a true cylinder using a spindle roughing gouge or bowl gouge. Then use a standard parting tool to turn a 7⁄16"-long × 21⁄2"-diameter tenon on the tailstock end (Photo C).
3 Switch out your cup center with a 4-jaw chuck, and remount the blank with its tenon clamped into the chuck.
4 Referring to Figure 1, turn the uppermost 51⁄2" of the outside of the vessel to its finished shape with a bowl gouge. Turn the lowermost section to a cylinder for now. (The extra mass will provide stability when hollowing out the interior.) Undercut the area at the joint line by about 1⁄8", using a detail spindle gouge (Photo D). Now rough out the edge of the bead at the top to a 15⁄8"-diameter, but don’t undercut it yet.
5 Still using the detail gouge, turn a flat on the top end of the vessel (Photo E) for better bit registration when drilling the hole.
Hollow and remove the top section
1 Outfit your tailstock with a drill chuck. Attach an extension to a 1"-diameter Forstner or multi-spur bit, and mount it in the chuck. With the blank spinning at about 500 rpm, advance the tailstock to drill a 63⁄8"-deep hole (Photo F). (If your extension isn’t long enough, just drill as far as you can for now, and complete the job after removing the top section.)
2 Begin to hollow out the top section, accessing what you can with a straight scraper or the Ci3 Easy Finisher. Then move to the Ci3 Easy Hollower to turn the corner (Photo G). Hollow out the section to a bit below the joint line. As shown in Figure 1, remove material by “scooping” it out in successively deeper passes. Use a ruler and a thick wire with inward-turned ends set 1" apart to gauge your progress (Photo H). Aim for a 1⁄4" wall thickness in the area just below the joint. Leave the area above the joint about 3⁄8" thick, tapering to 1⁄4" at the top of the vessel, as shown in Figure 1.
3 In preparation for parting off the top, first draw reference lines across the joint area for grain reorientation during reattachment later. Also, insert your drill extension rod into the hole to catch the lid once it’s freed. Then part away the top section with a 1⁄16" parting tool, holding it at 45° to the vessel axis (Photo I). (Using a thicker parting tool would cause the top section to sit too deep in the main body when reattached later.) Remove the drill extension rod and top section.
4 Refine the top edge of the body with a detail spindle gouge for a complementary fit with the edge of the top section. Make the surfaces mate as well as possible to ensure a good glue joint. Test and fit as you work, sighting for gaps on the exterior and feeling for them on the interior.
Hollow and refine the interior
1 Hollow out the middle section of the vessel (Photo J with Inset). You can use a bowl gouge for the roughing, followed by cleanup with a scraper, but I find that the Ci3 Easy Finisher cuts quickly and with enough finesse to do the whole job. As before, take a series of progressively deeper scoops, working from the center outward, to remove the material. Use a caliper to check your wall thickness as you progress (Photo K), again shooting for 1⁄4"-thick walls.
2 Turn the outside of the bottom section to final shape, working down to about 5" from the joint line. Now finish hollowing the interior, gauging the 1⁄4" wall thickness from the exterior walls and stopping when you’ve reached a depth that meets the bottom of the drilled hole. (You won’t be able to gauge the bottommost 3⁄4" or so of wall thickness yet.)
3 Use a commercial cone center mounted on your tailstock (or the shop-made version slipped over a live center, as shown in Figure 2) to hold the inverted top section against the top of the vessel. Center it carefully, and then use a detail spindle gouge held in scraping position to refine its underside surface (which will be the target for many exploring fingers), as shown in Photo L.
4 Back up the tailstock, apply yellow glue to the mating edges of the top and body, and glue them together using the cone center on the tailstock to apply clamping pressure (Photo M). Use the reference lines drawn earlier to align the top as originally oriented, with its edges projecting evenly all the way around.
Refine the reassembled exterior
1 With the vessel still attached to the 4-jaw chuck, refine the exterior surfaces using the detail spindle gouge. Clean up at the joint line to remove glue and to ensure that the areas adjacent to the joint are truly concentric. Use the offset scraper to smooth the interior at the joint line. Turn down the outside edge of the bead to its final diameter, and undercut its outside edge. To do the final rounding, insert the gouge into the hole and pivot it around to the outside (Photo N).
2 The next step is to double-check the depth of the interior, add 1⁄4" to that measurement, and then mark off that length at the bottom of the vessel. To do the job, I use the simple depth-gauge jig shown in Photo O. It’s just a stick with a hole drilled through the center to accept a 3⁄8"-dia. dowel. A bolt and wing nut squeeze together a slot bandsawn inward from one face and intersecting the hole to pinch the dowel in place.
To use the jig, first place the stick across the vessel opening, bottom out the dowel inside the vessel, and then lock the dowel in position. Next, place the dowel alongside the vessel, with a pencil held against its end, and mark that location at the bottom of the vessel (again, as shown in Photo O). Accounting for the pencil tip offset, calculate a 1⁄4" distance outward from the interior vessel depth. After scribing a line completely around the vessel at that location, part in enough to leave 1"-diameter of material remaining. This establishes the vessel bottom.
3 Using a detail spindle gouge, finish refining the exterior down to the parted line (Photo P). Then sand the vessel through 320 grit, and remove it from the lathe.
4 Dismount the vessel to make the jam chuck for finishing the foot. Begin with a 10"-long piece of 2"-square hardwood, squarely crosscut at its ends. Mount it in the 4-jaw chuck, with its opposite end supported by a tailstock center. Turn down the outermost 8" of the piece to a hair less than 1" in diameter.
Slip the vessel completely onto the chuck to check the fit. If it rattles at the opening, wrap masking tape around the chuck to build it out for a snug fit. Also attach a 1"-diameter disc of 100-grit sandpaper to the turned end of the chuck, using spray adhesive or double-faced tape for a better purchase on the vessel.
5 Slide the vessel onto the jam chuck again, and bring the tailstock up against the end of the turning blank, ensuring that the tailstock center sits in the existing divot. Use a spindle detail gouge to turn a shallow recess in the vessel bottom (Photo Q). Then finish-sand the recess.
6 Dismount the vessel and use a small handsaw to cut away as much as possible of the tenon without scarring the base. Chisel away the remaining nub, and then sand the surface.
Apply your preferred finish. I wiped on two coats of Watco Danish oil, followed by a thorough buffing to bring up the shine.
About Our Author
Michael Kehs has been carving and turning wood for 30 years. In addition to creating award-winning designs for commission and exhibition, he teaches woodcarving and turning at his studio in Bucks County, Pennsylvania, and at the local Woodcraft store in Allentown, Pennsylvania.
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