The Nakashima Conoid table was a design I came across in George Nakashima’s book The Soul of a Tree. Part memoir, part woodworking manual, and part esoteric philosophical discussion, I found this book to be highly inspirational in choosing my next woodworking project. George Nakashima, a studied and experienced architect, had an appreciation for Japanese architecture and traditional design. So when I looked at his table design, which was both intricate yet subtle, I wanted to find a way to incorporate traditional Japanese Timber Frame joinery.
Enter Ari Shiguchi.
My version is substantially more complicated than the traditional.
Ari Shiguchi is a Japanese timber frame joint, largely used with flooring joists designed to take great weight loads. It’s a dovetail with a recessed shoulder that thrives in a downward force application and Japanese structures built with it have demonstrated their ability to last for generations. In a traditional application, no adhesives are used because Japanese homes are built in a structural, yet knock down manner. However, in this application, cut at ten degrees to match the splay of the legs, this created an incredibly rigid base that supports a hefty table top of cuban mahogany.
To make matters more complicated, I used the joint in a doubly unorthodox manner. For starters as previously mentioned, it will be angled in at 10 degrees and secondly, locked into a bridle joint, which will secure the bridle joint with the lateral table supports.
For the ari shiguchi mortise and tenon, layout is absolutely key. Everything is based off a center line marked on the tenon side and mortise side, so that when ultimately assembled, or working toward that ultimate assembly, you can use those center lines to keep everything in plane. In Japanese joinery of this kind, the idea is to split your layout lines to ensure the most snug of fits. If necessary, you can even peen your tenon with a mallet to help squeeze it into the mortise, and then use a spray bottle with water to re-hydrate the peened tenon and have it expand in the mortise. Also, the traditional ari shiguchi leaves a slight gap, about 1-2 mm at the top of the dovetail, which allows for the shoulders of the joint to be sucked tighter against the mortise. I didn’t do that here, but it’s certainly an option for those wanting to recreate it.
The shouldered bridle joint that receives the tenon.
The tenon layout.
The mortise itself is a bit trickier because you need to match the angle at the seat of both the dovetail and the recessed shoulders, so I did that by using the opposing leg assembly as an angle guide, that way any imperfections are transferred through and I don’t have to worry about nailing a perfect ten degrees every time.
Paring the mortise.
Dry fit and ready to go.
The joineries at the base of the conoid trestle legs is much simpler in comparison to the structural top. An angled bridle joint will be pegged from both sides, and lateral support along the width of the table will be provided by a “third lap” of sorts, a half lap, except one side’s mortise is cut to two thirds, and the other side to one. In my opinion, for this application, it makes a much sturdier and rigid base.
The angled bridle joint is quite simple. Mark your layout on both sides, don’t cross your base line, and then saw your waste out in an “X” to leave a small pyramid worth of waste in the middle. Then knock that out with a chisel and refine the seat. I made my own dowels with a dowel plate, utilizing the same mahogany that I used for the entire base.
The third lap gets quite tricky as you have to saw in this case, into an already assembled base. I’m sure setting this up ahead of time is an option, but I had already glued up the main structure before getting to this joint. The “X” technique as used on the bridle joint could have been useful here, but I liked going with cutting relief cuts and knocking out the slatted waste with a mortise chisel. It just felt more natural and safer being that close to the completed leg assembly.
The base joineries for the Conoid.
The bridle joint dry fit.
Sawing the “third lap”.
I used locally sourced Cuban mahogany and had two sequential slabs. When unfolded out, they create the book match that is so iconic in a lot of George Nakashima's work. These are well dried and dimensioned slabs, so I won't be messing with c-channel or battens (which don't really keep slabs flat anyway but that's another story) and instead will just be worrying more about nailing the perfect book match orientation.
To do so, I laid the slabs out on top of each other in the book match configuration and then adjust them till they combined, are the final width. In this case it was 36". Then I mark the center point on the end grain and use the track saw to rip the top slab and simultaneously score the bottom slab. After removing the top slab, you line the track to the kerf and complete that cut. The result is a perfect book match with a central line that can assist in lining up your ends and ultimately your base as well.
To nail the glue line perfectly, I fold the slabs down in the book match and use the jointer plane to joint both boards at once. This will create a congruent fit that, even if not perfectly square, will be perfect when brought together.
The ends are trimmed with the track saw after clamping and the domino was used to make sure alignment is not an issue.
My rendition of the Conoid.
Real Milk Paint Company's Pure Tung Oil is utilized as the primary finish for the top. Unlike Hemp Oil which was used for the base, Pure Tung Oil is a cross linking, polymerizing oil, that when layers are properly built and cured, is completely water proof. It is all natural and leaves a beautiful natural look on the wood. I apply multiple thin coats, probably 10-12 over the period of about a week, and then allow a few more days for final cure.
Go check out the video for more!
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