The Nakashima Conoid - Live Edge Table

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. George Nakashima's conoid design series specifically is one of the most celebrated furniture series of the 20th century. A lot of folks are extremely familiar with the conoid chair, but this conoid trestle style table is incredibly gorgeous and presents its own set of building challenges. 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.

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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 will create an incredibly rigid base that will support a hefty table top of cuban mahogany.

To make matters more complicated, I’m going to use 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.

To begin, after dimensioning all the boards, the joinery is laid out in .01 mm pen. The bridle joint is divided into thirds across the thickness of the boards to maintain maximum structural integrity. After the lines for the mortise are sawed by hand, the middle is knocked out with a mortising chisel. The tenon, the middle third portion of the bridle joint, which is technically a shouldered bridle joint, is cut on the table saw, by utilizing a number of relief cuts, and then clearing out the waste with a bench chisel bevel down. The faces of that tenon are cleaned up by using a router plane closer to the shoulder and then a jack plane to meet the router plane groove. This is done as an alternative to using a rabbeting block plane, namely because I don’t own one. It’s a bit more time consuming and these old vintage router plane irons are incredibly difficult to sharpen, but it in the end it works out just fine.

When cleaning up shoulders, or any sort of end grain in these joints with a chisel, dampening the wood makes paring phenomenally simpler. I’ve traditionally used a spray bottle with denatured alcohol, but a few times with this mahogany I used water, which actually seemed to work a lot better and give me a cleaner result.

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 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 do 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.

To achieve the dual angle detail on the conoid leg assemblies. I use the track saw and do a series of cuts, including a somewhat sketchy plunge cut and finish off the cuts with my bench top saw. The plunge cuts with the track saw are best done extremely slowly and track saws are notorious for kicking back during a plunge cut so I definitely caution everyone to exercise extreme care here.

To clean up the sides from their saw marks, a jack plane and a card scraper gets the job done.

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.

For finish on the base, I used the Real Milk Paint Company's hemp oil. Hemp oil is a pure polymerizing natural oil that when built in layers, creates a durable finish. It's not waterproof like tung oil (we'll get to that later), but it does create a deep, long lasting, rich finish that is perfect for a table base. I've grown accustomed lately to applying extremely thin coats in multiple layers to build these finished and get the perfect sheen and the results really speak for themselves.

I'm using some locally sourced Cuban mahogany and have 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 lay 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.

After everything is out of the clamps, the slab is planed flat by hand, the edges are cleaned with a wire brush, and a spokeshave and low angle block is used to add a slight chamfer all around.

Real Milk Paint Company's Pure Tung Oil is utilized as the primary finish for the top. Unlike Hemp Oil, 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.

After the top is cured, slots are cut into the base with the domino to allow for z-clip fasteners. As wood moves along its width, z-clip fasteners are a great low profile option for attaching the base to the top. The slots are cut a fair bit wider than the clip itself so that the expansion and contraction of the wood allows for the clips to move side to side as necessary. A simple pan head screw fixes it to the table top.

After the table top is attached, the table is done.

George Nakashima's legacy is in his designs left for generations to re-create and interpret. This by no means is a pure re-creation of the conoid. The original conoid table has no upper stretcher and certainly does not have an over complicated and frankly unnecessary Japanese timber frame joint. However, in my opinion, this variation of the design would be something that George Nakashima appreciated. It's structural, it's strong, it's long lasting, and the building of it was equally as beautiful as the finished product. During George Nakashima's time in India, he lived in Pondicherry and practiced yoga religiously. As he returned to the United States and began his furniture exploits, it was said that his furniture craft became his yoga. Being lost in your craft is a beautiful thing, and I hope you all are inspired to make, create, and get lost in the movements and careful thought required to build such a thing.

Thanks for following along. Be sure to watch the video and head on over to my website for more of my offerings and what I'm up to.

Cheers.