Parquetry

Parquetry is defined as a repeating geometric pattern in wood. As I understand, in French this is referred to as “jeux de fond”. Before you comment, yes, the same term is used for flooring with a repeating arrangement.

A parquetry pattern of diamonds and chevrons covers the majority of Oeben’s table both inside, and out. This is, perhaps, the easiest facet of this project to re-create in my opinion. To begin identify the pattern. In this case, it’s a series of chevrons symmetrically distributed about the center line at their low point.

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From a photo, I counted eight complete chevrons across the front apron, four to either side of the center line, with a half-chevron to each side. The final piece of information is knowing the height of the complete chevron. I luck out in this case! The complete chevron spans the height of the main box, a dimension with which we are familiar already!

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Using this information, I drew a paper pattern without making any linear, or angular measurements!

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This is my preferred method of operation as it reduces induced errors that can creep into measurements. While I have no evidence to support the claim (at present), I’ll bet that this was the way Oeben operated too.

Since there are multiple identical pieces in a parquetry design, the information shown on the template can be used to create cutting jigs. I chose the “slow road” in this case, laying veneer strips directly on the template, and marking/cutting them. This was a prototype, and I won’t be doing that for the final version.

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With sufficient numbers of pieces cut, assemble the design as a large sheet. It should have plenty of overlap. Various other elements, like the purpleheart frame will get cut into this sheet of chevrons for an exact fit. Drawer fronts are veneered from the “scraps” leftover when their apron cavities are trimmed. In this fashion, the pattern is preserved. Everything lines up.

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Legs! – The making of…

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

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.

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.

Tools used to refine the leg profile

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.

Cabriole leg 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…

Oeben Book Rest

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!

Why Build Prototypes?

You might wonder why go through the effort of constructing a prototype when building a new piece? After all, it requires material, and at least as much time to create it, as the “official” piece. Why not just apply those resources to the finished piece?

So here’s my story…

I embarked on this Oeben re-creation, after much study, by constructing a three-dimensional SketchUp (SU) model. The thought being build it in SU to work out the bugs in the process. This may come as a surprise to you, but ALL of the aprons on this table exhibit a curve to some degree (fortunately they’re not compound!). There are very few flat exterior surfaces on the piece! At the time, I thought the easiest way to handle this would be to begin with thick material, then shape it appropriately. I drew it this way, and didn’t look back. Life was good… Or was it?

Now it comes time to cut wood. So, I choose an appropriately thick piece of stock for the “Main Box” front. The “Main Box” being the “drawer” that extends forward when the top is released and retracted. It contains all of the other “hidden” components. For several weeks, I continue working – yet, something keeps bothering me. Each time I look at the curve for the front, it seems out of place, like it’s inappropriate, and not representative of what I see in the original. Finally, I sit down, and look through the photos. I come across an image taken of the bottom. It’s available on the Getty Museum’s website. I’m showing an outline of its shape below. The two open spots at the bottom are where the legs protrude.

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From it, I calculate the extent of the curvature at its most extreme, and learn that my drawing is about 1.5 cm too shallow. Not necessarily a show stopper. But wait – I look closer. Not all of the aprons were created in this fashion! It appears that the board comprising the rear apron was bent. Looking further still, I come across this photo showing the underside of the “Main Box”.

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It shows a uniform thickness board bending in a gentle arc composing the front of the “Main Box”. So, it appears that my plan to work a thicker board to shape is incorrect. Now the question becomes how did Oeben’s craftsmen accomplish this?

There are several methods for creating curves in wood. The most basic is to cut perpendicular kerfs along its inside. This leaves voids allowing room for compression. However, these spaces are highly visible, and from the previous picture, not in evidence in this table. A second method involves slicing the board into thin planks along the grain then gluing them back together while clamped to a form. Once the glue dries, the board maintains the shape. I have witnessed instances where this was done and difficult to detect, but I don’t believe that this method was used either. A third procedure involved steaming the board and bending it. While this seems to be plausible, was this historically correct for the period in which the table was made?

Following a brief exchange with Patrick Edwards, this appears not to be the case. According to Patrick:

Oeben did not steam bend furniture.  French curves are sawn from solid wood.  Although Denis Papin (1647-1712) invented the steam pressure cooker, no one thought to use it to bend wood until the 19th century.  Complex two dimensional curves are “sculpted” as you suggest using chisels and scrapers.  Final truing of the surface was with toothing planes.

So, my initial methodology was correct, and the aprons were hewn from thicker stock.

If I hadn’t taken the time to construct the prototype, I may have missed out on this learning opportunity. Not only do prototypes help you work through unforeseen issues that weren’t caught during the modeling phase, and provide valuable practice for building the final version:

If you can’t get it right on the prototype, how do you expect to get it right for the final piece?

The process of creating a prototype gives insight into how the piece was originally made – living archeology, if you’re paying attention!

So, what becomes of the current prototype now that this issue has come to light? After all, good material and effort has already been expended to reach this point. Rather than discard it, I decided to laminate material and “thicken it up”, upon consideration. While this will allow me to obtain the appropriate external shape, the interior will remain as it is presently. It’s a compromise I will live with for now…