Published Sep 3, 2019
Have you ever been using a store-bought throwing rib and thought, "if only this rib was shaped like this...or...like that?" Most of us make do with the standard shapes of ribs in our throwing because the more specialized fancy ribs can get expensive or it just seems daunting to make our own. But, it is surprisingly easy to make your own custom ribs if you have some basic woodworking tools. And it can be pretty darn cheap if you have access to a wood worker's scrap pile.
Making your own customized ribs is not only a way to help facilitate your personal aesthetic touches, but, as Robert Balaban puts it, it "permits creativity to extend from the clay to the tools." In today's post, Robert shares his system for creating custom hardwood throwing ribs. - Jennifer Poellot Harnetty, editor.
I’ve always looked for ways to improve the quality of my art by fashioning customized hand tools to facilitate the shaping my vessels. In these efforts, I’ve developed a simple system of constructing hardwood ribs for a variety of throwing purposes. This permits creativity to extend from the clay to the tools. Many studio visitors and students have enjoyed using or creating these tools and often leave the shop with a couple of customized ribs that make a lasting impression on their craft. Custom hardwood ribs are easy to create, and can be constructed in under one hour using skills that any potter can master.
Choosing the Best Wood
I've experimented with several types of wood, from the most exotic (mpingo, purple heart, bocote, and cocobolo), to mahogany and cherry, coming my way from a wood worker's scrap pile or from my own backyard. Maple, osage orange, black locust, and even mountain laurel also work well. Red or white oak and poplar are hard to use because they swell when wet and typically have large growth rings that make a consistent edge difficult to achieve. Usually any dense hardwood with resistance to water damage is appropriate. The best, cheapest, and locally available wood (not from the fragile rainforest) is American black cherry. The 5/16-inch thick stock is a good starting material. Slightly thicker or thinner material can be used depending on taste or task. If you buy wood, a couple of dollars of5/16-inch wood can generate 10 to 20 ribs.
Generating and Transferring Designs
Creating different ribs for novel shapes or tasks can be done using paper, pencil, and a French curve or other guide or pattern to help generate that perfect curve or angle. You can also use computer drawing programs, draw free hand or simply copy more familiar rib designs and modify them to your needs or hands. I use a versatile French curve-style rib for working on the inside of vases and other forms. The first step in making this type of rib is to trace the template onto paper and secure it to the piece of wood.
Making the Rib
The next step is to cut the wood, using a hand coping saw, scroll saw or bandsaw (figure 1) and leaving the traced line on the rib to permit fine tuning later.
Caution: When working with power tools, read and follow all manufacturer safety materials before use. Dust from some woods can be toxic or contain allergens, therefore always work in a clean ventilated area with a respirator or dust mask for the cutting and sanding stages.
With the completed rough cut shape, the next steps are to finish the outline, taper the edge that will guide the clay, and generate a true sharp edge to create a smooth finish on the clay. The best tool to quickly accomplish all of these tasks is an oscillating spindle sander. It’s a rotating cylinder of sandpaper that moves up and down with interchangeable spindles of different diameters that can be used to refine the various curves of your rib (figure 2).Alternatively, different size dowels with sandpaper wrapped around them also work, they’re just slower.
Next, true the shape of the rib blank by sanding the rough edges using an 80-grit sandpaper. If you make a rib with an arc that’s smaller than the smallest spindle available, or have a square or triangle in the rib, these will need to be hand filed. For the French curve rib, make a groove using a 5/8-inch spindle to fit your index finger at the small end (see figure 2) and to allow for leverage on the clay when pushing the larger belly end to the inside of a pot. This customizes the rib to your throwing style as well as your specific grip.
Now create a tapered edge to guide the clay using the largest diameter spindle or a sanding block. This is done by approaching the spindle at an angle with the rib blank and then sanding it down to a 45° angle. Taper all outside edges of the French curve to accommodate all your throwing needs. The small circle on the end of the rib is also a very useful part, taper all edges here as well. Finish the taper on the larger structures, then make more severe tapers around any sharp features to help guide the clay through tight areas. Then round the all of the remaining edges for a better feel (figures 3 and 4).
To customize the rib even further, add finger holes to improve grip and leverage. Hold the rib as you would while throwing and mark the area around your fingers. (Clamp the rib flat to a backing board to drill the finger holes). The back up board ensures that the drill bit will not split out the back side of the rib (figure 5). Mark an outline of your finger’s grasp with a pencil then taper the hole for a customized fit. Return to the spindle sander and insert the 1/2-inch sanding spindle into the hole. Sand the inside of the hole and then angle the rib while it is on the spindle to generate an oblong tapered hole that matches the angle of your fingers (figure 6).Finally, sand the rib by hand using 200 then 400 grit sandpaper—only a couple of minutes with each grit is necessary. A good trick is to then wet the wood and dry it. This causes any wood grain that might rise with water to do so and then you can sand this off for a very smooth and resilient surface.
The finish you use can vary. Using bare, untreated ribs is fine if they are made with a strongly water resistant wood like teak. Alternately, different oils and several different waterproof varnishes can be used to seal the surface. I have found that the oil-based Minwax Clear Shield finish or marine varnish is very strong and the clay slips nicely along this surface. Follow the oil manufacturer’s directions on application and appropriate drying times. Finishes will still wear off and need to be reapplied.
Using these techniques, you can make a rib, try it out on the wheel the same day, make adjustments, finish/dry it overnight, and have it ready for the next day.
Robert Balaban is a functional potter and teaches classes in his studio. He not only creates ribs from dead trees found in the woods, but he also specializes in creating safe glazes from the natural products in his gold producing backyard in Maryland.