One of the (many) barriers to making staked furniture or chairs is wrapping your head around the compound-angle geometry. And then figuring out how to execute it at the bench.
The new Crucible Chairpanzee ($16 plus shipping) does the trigonometry for you, allowing you to translate rake and splay into sightlines (which create your layout lines) and resultant angles (which is the setting of your sliding bevel).
This allows you to easily design new pieces of furniture with compound angles and to replicate angles from existing pieces of furniture from photos.
The Chairpanzee is a clever sliding calculator that is printed and assembled in the United States. Here’s how we use the Chairpanzee on a chair design (though it can be used for tables, stools or any other piece of staked furniture).
To calculate the “sightline:”
1. On the underside of the seat, draw a line connecting the two front leg mortises (as shown above). This is the baseline.
2. Move the calculator’s slider to the desired splay angle in the top window.
3. Next to the lower window, select the desired rake angle. The number shown in the adjacent window is the sightline angle.
4. Draw the sightline angle on the underside of the seat using a protractor. The 0° on the protractor should be directly on your baseline.
5. Repeat steps 1 through 4 for the rear legs.
To calculate the “resultant:”
6. Confirm that the calculator’s slider is set to the desired splay angle in the top window.
7. Next to the lower window, select the desired rake angle. The number shown in the adjacent window is the resultant angle.
8. Set your sliding bevel tool to the resultant angle and place it directly on the sightline on the underside of the seat.
9. Drill your mortise. Keep the drill bit perfectly parallel to the blade of the sliding bevel.
The Chairpanzee is available for immediate shipment. We hope that some of our retailers will also carry this product for our international customers.
In the coming week I’ll post a video that shows how it’s used.
“Make a Joint Stool from a Tree” was a first on several fronts for Lost Art Press. It was the first book in full color, the first to use a larger format and the first to have a dust jacket.
It was also the first “edition” book Chris designed, with the guidance of Wesley Tanner (who would later design the award-winning Roubo books for Lost Art Press). That’s who introduced Chris to the venerable book designer’s bible: “Methods of Book Design,” by Hugh Williamson (1956).
It took so long…they were working on it for more than 15 years (most of that prior to signing on with Lost Art Press). A fun drinking game: Every time Peter’s outfit has changed in the pictures, take a shot. (On second thought, that’s not such a good idea…). You can also watch Peter and JA age and change throughout the pages.
Now that the stool is all assembled and trimmed, it’s time to apply a finish. At this stage, you can use your favorite finish, but if you would like to explore period-style work further, then oil-based paint is an excellent choice for a period finish. This is attainable, but with some cautions.
Surviving artifacts sometimes have remnants of their original painted finish, and these can be analyzed and the pigments and vehicles identified.
This analysis is rarely applied to “clear” finishes; it usually centers on surviving colors appearing on period works. We have benefited from colleagues who have shared with us the findings of their studies, but there is still a long way to go in this aspect of 17th-century furniture studies.
Paint consists mainly of a color, the pigment, that is dissolved in a medium. In many cases the medium is a plant or nut oil, such as linseed oil (from the flax plant) or walnut oil. It is often thinned with turpentine. One aspect of period paints that is best avoided today is the use of lead as an ingredient. The lead served to dry the oil, and in its stead you can add just a few drops of Japan drier, which will help the linseed oil dry a little more quickly. A little umber pigment mixed in with your other colors will also help with drying; usually it’s too small of an amount to affect the color much.
For our stools, we paint them with homemade paints made by grinding dry mineral pigments in oil, or an oil/varnish combination. The available colors are usually earth colors – reds, yellows, browns – and carbon pigments – lampblack or bone black. Artists’ supply outfits are a good source for dry pigments. Use their linseed oil also; it is better quality than the boiled linseed oil from the hardware store.
Red is the standard color based on what little evidence we have seen from studying period pieces. We use iron oxide pigment. It goes by various names: iron oxide, Indian red, Venetian red or red ochre. The best tools for mixing the paint are a muller and a piece of plate glass. The muller is essentially a flat-bottomed pestle made of glass. Like many good tools, they are expensive. You might try your first batches of paint by grinding with a mortar and pestle, or even just a palette knife on glass. Then if you plan on going further, you’ll want the muller and glass.
Make a ring of pigment, and pour in some of the medium. Slowly mix the medium and pigment together with a palette knife, then take the muller and work in a circular motion to dissolve the pigment in the medium. Mix up enough to paint your whole stool; you don’t want to stop during the painting to mix up more paint.
Use a clean, soft, natural-bristle brush to paint the stool. Period brushes were round; the most common modern ones are flat. If you want to try round ones, get them from an art supply store rather than a hardware store. Thin paint will have a better chance at drying than thicker, more opaque paints. Several coats will result in a more solid color and finish. You can combine the red and black in a contrasting application, using the black for the mouldings, or even pick out aspects of the turned decoration in alternating red and black.
Warning: Linseed oil generates heat as it dries. This can cause spontaneous combustion of rags and brushes and any other absorbent materials that have come in contact with the oil. After use, put all such materials outside to dry in a well-ventilated place for at least 24 hours in a temperature of not less than 40° Fahrenheit. Or you can thoroughly wash all contacted materials with water and detergent and rinse.
Recent research at Winterthur Museum and the Museum of Fine Arts, Boston, has identified examples of 17th-century paint made with pigments mixed in thin solutions of hide glue instead of oil. To do this yourself, prepare the glue granules just as you would for using adhesive, but with more water. Fill the bottom of a glass jar with the glue granules, add enough water to cover them plus a little more, and let it soak overnight. When you’re ready to make paint, heat the glue mixture slowly. If you don’t have a dedicated glue pot, you can put the glue in a glass jar sitting in a few inches of water in a pot. Stir regularly. Keep the mixture thin. When the glue is nice and thin, turn off the heat, and you’re ready to mix the paint.
Just as with the oil, start by sifting some pigment onto your plate glass, or in a mortar. Then pour some glue in and start mixing them. Keep adjusting by adding pigment and glue until you reach the solution you’re after. Painting a whole stool with this paint is tricky; the glue thickens as it cools. It requires a little tinkering, so add water if it thickens, and return the glue to the heat from time to time as well. This protein paint needs a finish over it, or it can rub off. The research indicates a plant-resin varnish as a top coat.