Heavy Duty Shelves – Completion

Continuing on from last weeks post on the fabrication of a set of shelves that I’ve designed for my own personal use to store bulky stuff, tool boxes, and miscellaneous items that have been floating around our home for far too long. My initial design for this shelf included a big x-brace across the back of the shelf to add support against racking. Design-wise I’m not a huge fan of x-braces, but structurally they do work really well. However I ended up changing the design a bit, eliminating the x-brace in favor of a series of horizontal braces (i.e. nuki in Japanese).

The ultimate reason leading up to that decision was due to my own mistake when buying the lumber for this shelf, and simply not buying enough to account for the x-brace. I was also under a time crunch to finish this shelf before the end of the new year, so rather than buying more material I looked the design a bit more and bet that if I added 4 rows of horizontal nuki across the back posts, using material I had on hand, the overall structure would still be strong enough for my purposes. I also think the design looks better overall with the horizontal nuki, even though they won’t be very visible with the shelves fully loaded. Here’s how the updated design looks rendered in Blender.

So with the decision made regarding switching to horizontal nuki for the cross-bracing, I had some more mortises to cut in the back 4 posts. Here is a rendering of a cutaway view of the joint I decided to use. This is the same joint I used on another set of shelves that I detailed in another series. In the cutaway view you can see that overall the joinery is pretty simple, just a horizontal nuki mated to the post with a simple cogged joint, and a wedge locking it all together.

Below you can see a set of these mortises roughed out on the mortiser. On the left side of each mortise are layout lines for the wedges that will secure theses joints, and on the right are layout lines for shallow haunches that make up the cogged part of the joints.

Here’s a view of both sides of the joint after everything has been cutout. I used the router method again to trim the insides of these mortises. If you look closely you can see where the router starts and stops. You can also see a tiny bit of undercutting that my current bearing bit produces. These are perhaps not the cleanest looking mortises, but they are solid where it matters; a snug fit around the perimeter of the joint producing a clean look when the nuki is inserted, and a snug fit on the cogged portion. Also a slight bit of undercutting on mortises like these makes assembly much easier. Sliding a nuki through 4 posts and their corresponding mortises becomes really challenging if the joints are too tight. On houses these joints are usually quite loose on the sides (by a couple of millimeters) to allow easy fitting of a nuki that has to pass through multiple posts.

Below are the nuki clamped together for batch cutting the notches that mate with the cogged portion of the previous mortises. I cut the shoulders on the sliding table saw, and followed up with a router to clear out the center portion of the notches. The final step was to lightly chamfer the corners of each notch to allow them to cleanly slide down onto the cogged portion of the mortises.

Below are the posts, with mortising finally complete, and ready for hand planing. The material here is construction grade hinoki, which has been kiln dried and is full of knots. Not the most ideal material, but it fit my budget for this project. I find handplaning construction grade wood like this enhances the overall appearance immensely, so first I added a light 3 mm chamfer to the 4 corners of each post, and then proceeded to hand plane the surface.

Kiln dried vs air dried wood planes completely differently, especially when it comes to knots. Knots in kiln dried wood are hard, crispy and brittle, and it can feel like you’re just destroying your kanna as you plow over them. That’s when a little bit of water can really work wonders to make planing a smoother and softer experience. I wiped all the posts with a damp rag prior to planing and the wood was so much more pleasant to plane than when it was completely dry. I try to allow the water to soak in and evaporate enough such that you don’t notice much or any moisture on the bottom of your kanna after running it across the woods surface.

Here are the kata-sage-ari stretchers during planing. I chose to use sugi for these short stretchers, mainly to make use of the cut-offs from the sugi shelf boards. This wood was also construction grade and full of knots, but since these pieces are relatively small I was able to pick and choose nice grain for the most part. This wood planed pretty beautifully dry, and didn’t require any wetting.

I also busted out a 80mm wide kanna for these stretchers, which allowed me to easily plane these pieces in one clean pass. This is an Osahiro white steel kanna, a generous gift from a friend, and it planes beautifully.

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And now we fast forward to the assembled shelf. I was under a time crunch to finish the construction details of this shelf, and get it out of my shop before the place closed down for the new year’s holiday here in Japan. And once I had the pieces brought back home I also had to assemble it in a bit of a hurry, so my apologies for not taking pictures during assembly.

Below you can see the end of one of the kata-sage ari joints poking through a post. I cut all the joints to be proud of the surface by about 3 mm. You can also see the end of the oak wedge poking out on the top side of the sugi stretcher. I made the wedges long, tapped them from the inside to the outside of the joint, and then cut the excess off flush with the inside face of the post. From there the shelves which are notched to fit around the posts, could be slid in place, and effectively lock the wedges by preventing them from freely sliding out.

Each layer of shelving is composed of three ~150 mm wide sugi boards. Initially I had planned to screw the boards down to the stretchers, but after assembling everything I realized that with the front and back boards being notched to fit around the posts, there’s really nowhere for the shelf boards to go, especially once they are weighted down with our junk. Technically the middle boards that are set between the inner and outer notched boards are completely free, but there is enough friction sandwiching them in place that I don’ think they’ll be going anywhere.

Here’s a view of the inside face of a post and stretcher intersection.

Here’s a view of one of the toshi-nuki stretchers running through one of the back posts. Hidden from view is the cogged watari-ago joinery, which is locked in place with an oak wedge above.

I didn’t bother planing the surface of the shelves themselves, but I did plane and chamfer the front edges. I also fit the shelves so that they wrap around each post and stop short of the post chamfers. These are the kind of details that you see a lot in Japanese carpentry and woodworking.

Finally here’s a not so picturesque view of the whole shelf fully loaded (It may look like a mess but I can assure things were much worse before we had a proper place to set all this stuff.). The shelves have a very utilitarian vibe, thanks in part to the knotty construction grade lumber, but overall I’m pretty happy with how things turned out, especially with these being constructed 100% with joinery that is secured with simple wedges. And the finished shelf is solid! With all the nuki and stretchers joined up, and wedges tapped in, the whole structure became incredibly rigid.

Well that wraps up this shelf project. I’m excited to see how this design will work out long term, but I have high hopes that it will be a long lived and solid piece of furniture. It should also be easy to disassemble and take with us when we move someday, and ultimately it will probably end up in my own shop at some point.

Thanks for following along