Wall Sculptures

At the April MWA club meeting Duane Gemelke showed us how he makes his unique wall sculptures. The process is deceptively simple: Turn a sort of platter with bead and cove pattern, cut it into strips (straight or wedge shaped), and glue the strips back together at an offset.

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Wood selection

The wood used should have these properties:

Duane started out with Butternut. While easy to sand, it does like to tear out while cutting. Next he tried soft Maple. The problem here was excessive movement due to the moisture introduced while gluing. Currently Duane works with Beech, which provides a reasonable compromise. Other possible alternatives to try might be Hickory or some (though expensive) exotic woods.

Wood preparation

Duane starts out with a board 3/4” thick. The size is limited by the swing of the lathe, so around 10” to 12” for smaller lathes, or 16” for larger lathes. For those larger sizes to boards can be edge-glued together. If the wood does have some figure, a thicker board can be re-sawn to get a book-matched appearance. Later the first cut can be made along the glue line so it will not show.

A small hole is drilled into the center, this will make it easier later to center the board on the lathe. Now a disk of the desired diameter is cut out of the board. Next one side of the disk needs to be flattened perfectly. Start out with a disk of scrap wood attached to a face plate. Flatten the scrap using a light sheer cut and frequently check flatness with a steel ruler. Now our work disk can be mounted on the lathe using the tail stock registered on the center hole to press the disk against the scrap disk. Flatten the work piece using the same technique used to flatten the scrap on the face plate. Light cuts are paramount as the disk is not secure. The remaining bump obscured by the tail stock is then sanded away by hand.

The flattened side of our disk is now glued to the flattened scrap on the face plate. The most secure way is a paper glue joint: Using wood glue glue the flattened sides of the disk and the scrap together sandwiching some craft paper or paper cut from a brown paper shopping bag. Doing it on the lathe, with the tail stock registered to the hole in the disk will make it easy to align it to the scrap on the faceplate. Add clamps and let dry. This will result in a secure bond, but the paper will allow it to be separated once the turning is done.

A less secure method (and hence not recommended) is to use double faced tape to glue the disks together. Duane prefers Heavy Duty Carpet Tape, which contains a thin layer of fabric (available ate Menards and other home improvement or hardware stores). Clamping pressure for about 15 minutes will make the bond more secure.

Turning

Next a pattern is laid out on the wood. Duane uses 3/8” beads and 3/8” coves, separated by 1/8” steps. Mark your layout with small marks, mount the disk on the lathe, and transfer the marks in the round by rotating the disk.

Cutting the beads and coves onto the flat face is a lot different than with spindle work. Gouges are not well suited due to the extreme tool angle required. On larger lathes a short gouge with a short handle could be used, though on smaller lathes it will hit the lathe body. A possibility would be a lathe where the head can be rotated to allow outboard work.

A staple during the yearly tool-making sessions is a simple cove tool, this works better than most other tools but still leaves some tear-out.

Duane’s solution is to use the Mike Hunter tool with the cup cutter. This tool does not require the bevel to rub, and it also allows to work uphill without creating excessive tear-out.

To save time, the beads can be rough-cut with a beading tool. The tools sides need to be ground slightly as unlike with spindle work the beads on the face will curve. However being basically a scraper the beading tool will result in some tear out, so the cup tool will be needed for a final cleanup cut.

Finish the cuts, and sand if needed. Separate the disk from the scrap.

Finishing Part 1

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It is a lot easier to finish the surface now than later when the individual pieces have been cut. An oil finish can be used, but to finish the exposed areas after the cuts will require time. An easier way is to use a lacquer from a spray can, but due to the strong (and unhealthy) fumes a well ventilated area is mandatory to use this finish. Another option is to use sanding sealer which has moderate fumes. Once the sculpture is assembled, a final coat of some other finish (lacquer, shellac etc) and then be applied.

Cutting the Strips

Next the disk is cut into strips. In our example Duane used slightly wedge-shaped strips, but straight cuts can be used as well for a different finish look.

A table saw or chop saw might be used, but the thick kerf and the danger involved cutting the last small pieces do not make those the ideal tools. Duane uses a bandsaw. For the first cut mark a center line down the back of the disk (again the small hole in the center will make this easy), and transfer the line over to the sides. For the actual cut Duane prepared a jig similar to a cross cutting sled, but adapted to the bandsaw. The disk is affixed to the sled using a couple of small pieces of double-faced tape, then cut.

Next sand the freshly exposed surfaces, again checking with a steel ruler for flatness. The thin strips are harder to sand than the larger pieces, so always sand before the next cut.

To cut the wedged-shaped strips, duane uses another jig: a board with wood strips affixed to it to make a tapering jig-like jig. This jig rides against the bandsaw’s fence. For symmetric work, two jigs are required with the taper angle reversed, one for each half of the wood.

Creating the shape

Now the fun part starts: Assemble the strips. Many variations are possible: Varying offsets, reversing every other strip etc. See the photos for some examples.

Duane does this on a board with a slit cut in. The slit allows to draw a witness mark to the underside of the strips to make it easy to find the desired position during final assembly.

Finishing Part 2

Once a pleasing shape has been found, draw the witness line and finish the newly exposed parts of the wood. Finishing now is important, it will make it easier to remove squeeze out during glue-up.

Final Assembly

Now on to final assembly: First glue up pairs of strips, using plenty of clamps and removing any squeeze-out immediately. Angle iron cane be used between the strips and the clamps to even out the clamping pressure. Then glue the pairs together, clamp and clean, and continue until all pieces are glued together. Duane prefers water-based clear drying PVA glue, such as Titebond Molding & Trim Wood Glue.

As the segments are glued together, the resulting structures can have shapes not well suited for regular clamps. Duane devised an assembly table that allows round pieces of woods to be placed in various holes drilled in the board. Machine screws through the wood pieces produce the clamping pressure.

Once all pieces are glued together and have dried, the back is sanded flat, as assembly will always result in some slight unevenness.

A final touch is to devise some method to allow hanging the sculpture to the wall. In earlier sculptures Duane used a keyhole bit in a router to cut a keyhole into the back. But the required depth of the keyhole brings it very close to the surface of the front. So Duane came up with another clever solution: Keyholes cut into round pieces of formica or a similar material. Drill a shallow hole the thickness and with of the formica pieces using a Forstner drill bit, and a slightly deeper hole (but not to deep to come close to the surface on the other side) where the keyhole will be located. Glue the formica onto the opening.

Ideas

The above process allows for a lot of variations to produce different results. Contrasting woods can be glued up resulting in the coves being a different color than the beads. The angle of the slices can be varied. The initial surface treatment can be modified. This is a great project to experiment with!

Handout

Duane Gemelke provided are great illustrated handout that describes the above process. It is available to MWA members who have signed up to the forum in the forums Library section.

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