Progress on the prototype carcass has reached a pause point while we patiently await the mechanisms.
The carcass aprons have been blocked out. That is, the joinery is complete, but the pieces have not been shaped according to their final profiles. This must occur after the mechanisms have been installed. To attempt to work in the reverse order would be challenging to say the least!
This provides an opportunity to focus on other areas, currently parquetry and marquetry.
I wanted to back up a moment, and explain how the legs got their start…
As with any cabriole leg, it begins with a pattern. From where this pattern originates is a mystery at least to me. I’ve consulted with several folks, but no one seems to know of a good design reference on the subject. The best I’ve found to date is the information provided in Jeffrey Greene’s American Furniture of the 18th Century. In this case, I am fortunate to have pictures of the Oeben, both from the Getty’s website, as well as from my time with the original.
Front view of the Oeben table
With this photo, and knowledge of the leg height, I have everything necessary to re-create the profile. Simply project the image onto a sheet of paper with two marks representing the height of the leg, then trace! The profile is symmetric, being cabriole, so this single profile can used on both sides of the leg blank without concern. Many thanks to the ladies at The Arts Council for allowing me use of their projector for this exercise.
At first, the curvature of the leg is subtle. That’s because the knee is hidden by the ormolu. Same for the “feet” which are covered by sabot. I had to interpolate in these areas which isn’t really a concern since, if I got it wrong, a) I can refine the profile during later stages, and b) it’s going to be hidden by ormolu anyway! The profile can be transferred to template stock, 6 mm thick plywood in this case. I use graphite paper for this…
Leg profile on template stock.
Now, it’s a straight-forward exercise in coarse, medium, and fine…Begin sawing out the rough profile, then refine it successively using rasps, scrapers, files, and sandpaper. The resulting profiles should be smooth, continuous curves without noticeable discontinuities. As I work, I’ll run my fingers along the edges while looking away to test. It’s easier to feel imperfections.
To refine the template, use rasps, scrapers, files, and sandpaper.
With the template “faired”, choose stock for the legs. The legs of the Oeben table are completely veneered, so none of the “core” grain is visible. If, however, you aren’t planning to veneer your piece, consider the grain direction of your blanks carefully. Lines running diagonally through the end grain will yield straight grain down the legs. Lines parallel to the faces in the end grain will produce bull’s eye patterns at the knees. Mill a face, and a perpendicular edge. Don’t bother with the other two sides. They’ll be removed in subsequent steps. Just be certain to use these two reference faces for all of your layout.
Trace the template profile on two adjacent faces of the leg blank.
Trace the template onto the blank aligning the “back” along the arris between the two reference faces. The “back” is defined to be the flat portion of the leg block at the top which winds up inside of the piece. You’ll have to flip the template over when switching faces. I like to strike lines defining the top and bottom extents of the template, and carry those around the blank to aid in alignment. Another point I neglected to make in my previous posting on the legs, it’s best to layout, and cut the mortises while the blank is still square, before you commence cutting.
Hopefully, this provides a more complete explanation of the cabriole leg process…
Moving on from the main box, it’s time to create the carcass starting with the legs. This facet is probably the most challenging aspect of this project to date since it is shaped in three-dimensions. Until now, each of the components has been shaped only in one plane. The top, and main box front, for example, only curve in one plane. They aren’t bombé! The French cabriole legs, however, are a different story.
The process begins with a large blank for each leg. Then, to paraphrase Michelangelo, you simply carve away anything that doesn’t look like a leg!
Needless to say, there is a considerable amount of waste. Eventually after a series of steps, coarse, medium, and fine, you arrive at the final profile.
The challenge in the end is to produce four “identically” hand shaped pieces.
As the carcass is constructed further, the entire unit will undergo another round of sculpting to bring it to its final form.
The book rest on top of the “Main box” is an unassuming feature. At first glance, it simply fills the space between the two compartment lids to either side. Only once those are opened, however, does the operator realize that there is more to behold. This video shows it in operation.
Construction-wise, there’s a bit more to it than simply mounting the hinges to the panel, and stop. It took a bit of trial-and-error to work things out to this point. Regardless, this is an elegant solution from the eighteenth century requiring only simple hardware. Features like this greatly enhance the overall value of the piece. Imagine being in the room when Oeben demonstrated this to the client. It’s almost magic!
It’s been a while since I’ve posted anything, so an update is in order…
After rectifying the topology issue with the front apron, all of the pieces were in place to assemble.
Of course, there were a few more details which had to be addressed after this picture was taken, but you get the idea. With the main box together, attention turned to the lids covering the compartments. The components for these were held against the main box, and marked to length accordingly.
Once assembled, they were profiled to match the contours of the main box front, and back.
Mortises for the hardware provided by David Sapp of Woodcraft of Franklin, TN were created. I finally got to use my mini-router plane. Isn’t it cute!
It took several attempts to determine the proper fasteners for the compartment lids. The areas where the hinges were installed were beveled which means there really wasn’t much material for mounting. If the screws were too long, they protruded from the “Main Box” side, and would interfere with the opening, and closing of the table!
Finally, the hinges were mounted, and ready for tweaking…
