Shell Carving Shortcut
||From prehistoric gravesites to Botticelli to Andrew Wyeth, the shell has figured prominently as an artistic motif.
As a motif in furniture design, the shell made its greatest and most durable mark during the Rococo. No study of 18th century furniture could ignore the omnipresence of the shell. Found on chair splats and knees, on drawer fronts and aprons, the shell (along with the acanthus leaf and ball and claw foot) is at the very heart of Chippendale design.
Admittedly, in this postmodern world of starkness and functional simplicity, carving is not much in demand. However, for those of us who are less interested in making artistic statements and more intrigued by the craftsmanship of fine furniture, the shell is an excellent introduction to decorative carving.
Accurate layout is important to successful carving. The natural geometry of the shell makes it easyto draw and stylize as well. Once you have selected a style, lay it out full size on graph paper. The grid of the paper aids measurement and provides a quick reference for dealing with curves.
Using a Lathe to Carve a Shell
Since most designs require more than a single carving and because most of us do not have an extensive selection of carving tools, we will do the basic shaping of the shell at the lathe. (Even if I only need one shell, I am likely to shape two at the same time. It's faster than roughing in the shape using carving tools and, because it produces two blanks, there is a backup ... just in case.)
Begin by edge gluing two boards together, adequate to accommodate your design. The edge gluing should be done with a paper joint. (A paper joint is merelya piece of paper inserted between two glued surfaces before clamping them together. The joint is used when the attachment is intended to be temporary.) Once the halves have cured, use a compass and a ruler to lay out the circle's circumference.
Cut to the outside of the line at the band saw. Leave 1/16 " or so of margin to remove evenly at the lathe. Glue this disc to a mounting block (usea paper joint) to attach to your lathe's faceplate. Once this joint has cured, mount this turning assembly to the faceplate and to the lathe.
With the drawn profile of the shell close by, shape the blank at the lathe. Follow the steps in the sidebar, below.
Handwork to the Rescue
Once you are satisfied with the profile, remove the blank from the mounting block. A chisel works well to start the paper joint to split. Next, separate the shell halves at their paper joint using your chisel. (Don't just snap them apart. Occasionally even a paper joint can resist separation enough to split the blank.)
|The author prefers using a carving knife rather than a V-gouge. He gets a more fluid line to his rays with this technique. Note the small board that the shell blank is paper joint-glued to: this helps control the blank while carving.
Again using a paper joint, attach the shell blanks to small boards. These boards enlarge the clamping options for your work and provide an alternative to directly clamping the work in a vise.
Next lay out the shell's rays on the blank. Marking the increments at the outer edge of the blank and at the center allows you to focus on the shape of the line as you connect the marks. Keep the lines clean. They need to be dark and thick enough to "read" easily.
To lay in or carve the lines that define the rays of the shell, I use a Swiss style chip carving knife. A more traditional approach would be to use a "V" tool. I prefer the chip carving knife for the sinuous quality of the line that it produces. And though it may take a bit longer, the results merit the extra effort. (If your design is more regular in shape and you want the rays to appear identical, a "V" tool may be a better choice.)
With the rays separated by cleanly cut lines, it is time to shape the rays themselves. For convex rays, I use a skew. To shape concave rays, use a gouge(or two).
Smoothing the shell is a matter of taste. For some designs leaving the tool marks is appropriate. For others you will need to blend the marks with small rasps or rifflers. This is slow going, but is worth the handwork effort. Resist the temptation to use a power tool. Flap sanders, pneumatic drum sanders and the rest tend to blur the quality of the carving. (The outer edge of the shell should be smoothed after demounting.)
Demounting the carving from the clamping block is again a matter of starting a tear in the paper joint with a chisel. Once free of the board, all that remains is to clean the residue of the joint from the carving's back. I use MEK to soften the glue and scrape it with a cabinet scraper. Apply the MEK with an eyedropper and keep the area moist for about five minutes. If one application and scraping does not clean the back, repeat as necessary. Avoid using a sander to remove the residue. It invariably rounds the back.
Four Turning Steps to Starting a Clamshell Carving