Saturday, March 21, 2015

Gateway (73)

Post 73 in an ongoing series describing the design and construction of a kabukimon, a type of Japanese gate. This is a project for the Museum of Fine Arts in Boston. Post 1 in this series can be found here if you'd like to start at the beginning. Each post links to the next at the bottom of the page. Recent installments also to be found in the 'Blog archive' index to the right of the page.


Approaching the final week of construction now. The gate will be delivered to the MFA on April 1st, and erected April 2nd. I hope to have it completed on April 3rd. A hotel room has been booked, a crane arranged, a mobile welding company arranged, and a box truck rented. Getting close now!

Construction-wise, as I work towards getting the left side paneled section together, I am coming to tackle the various patching tasks in these remaining sticks.

Here, a knot hole passing through the arris of a timber has been patched with a dovetailed sliding key:

Another view:

Temps have dropped in the past couple of days, necessitating the use of epoxy instead of Titebond II, which means a glue line is a little more apparent on the patches:

I can take some solace in the fact that the epoxy will make for a durable long term repair.

Here's the completed paneled section for the left side of the gate, sliding-dovetailed battens now fitted:

For a sense of scale in regards to the main doors in behind, the paneled section is 60" tall...

The copper piece at the left of the picture is the ridge cap for the kabuki. The main doors likely weigh 180 lb. (85 kg) each, maybe close to 200 lb., if I were to guess.

Most of the copper work has been completed and delivered - here are the parts which wrap around the feet of the main and rear support posts:

And these are the copper caps for the tops of the door stiles:

In front is the copper cladding for the sill.

The completed copper work means that the gate can be installed without having to wait on copper fabrication, which is a good thing. There are four large post caps (for the main posts and rear support posts) which are requiring some tricky silver solder work, and these are taking all the time for the fabricator. I'm hoping to have these parts in hand by the middle of the coming week so I can take them all for powder-coating. Worst case scenario is that the post caps are not completed in time, and they get installed a few days after the gate is put up, which I think is no big deal.

Anyway, today I was planning to assemble the entire left side paneled section, however before I could do that the flanking post needed to be fitted to the main post. This is much easier to do when the flanking post is not part of a larger assembly obviously. The attachment of the flanking post to the main post is by way of 8 sliding double-dovetail keys. However, before I could deal with that work, there was some patching to do: some large knots present on the arrises of the main (left) post. Here's one of those knots after excavation into a dovetailed trench:

And the other:

It was tricky to judge how much material to remove, as I didn't want the patches to be too obvious and it would be therefore better to keep them smaller if possible. I figured the epoxy would help stabilize the knot remnant, so I went and removed most, but not all of the knots.

With the trenches cut, the dovetailed patching keys could be fitted:

And here's the other one:

The remaining patching task on the main (left) post is this monstrosity:

I'll deal with that tomorrow. Hard to avoid a largish patch there, so I'll see if I come come up with something that looks halfway decent. That left post, with all its knots, is not the prettiest stick of wood by any stretch, although the front face of the stick is certainly presentable, and that is most of what counts I guess. The face shown above is the inside face.

While I couldn't fit the flanking post to the main post, I could at least tackle the sliding double dovetail keys, which I made from Burmese teak:

I also completed the same work on the flanking post which attaches to the right side main post:

The keys fit into place by dropping into the mortise and then being tapped home, like this:

A closer look at a completed pair of keys and their mortises:

Then to check that the entire key set would fit to its matching mortises on the main post. The left post still had those patches drying, however the right post could be checked:

Going down:

Fits fine:

My lucky day I guess. Sliding the parts together would be a disaster as the keys could move unpredictably and the pieces would be very difficult to separate afterwards. I don't want to connect them permanently right now. I'm just checking the engagement of the key group for the moment. Generally, if each key is fitted to the two mortises to which it associates, and the entire group can be successfully fitted, then the sliding-to-lock aspect is not likely to present any issues. For installation, the keys will be fitted to the main post, then the mortises plugged to trap the keys in place. Then the flanking post will attach.

All for today. I'll be in the shop tomorrow, and may have pics to share later in the day, so hopefully you'll wander over for a visit. Thanks for coming by. Next up: Post 74


  1. Hey Chris,
    Its great to see everything coming together on this project. Its all looking really good! Looks like you are having fun with all those sliding dovetails : )
    Are the dovetails tapered?

    1. Shawn,

      thanks for the comment and question. The dovetail keys are non-tapered. They fit with a slight interference.


  2. Hi Chris.

    Will there be any additional locking of the flanking post, to prevent it from moving onthe slding dovetail keys after mouting?

    Beautiful pictures as always.


    1. Hi Jonas,

      appreciate hearing from you. The flanking post attached to the main post with the keys, and when it mounts on, it slides down to lock. At the bottom it meets the granite sill, so that is as far as it can go in that direction. After it is in place, the kasagi beam fits on top of the flanking post and slides into the main post as well, which traps the flanking post in place altogether.


  3. Will the copper for the feet have the open seam soldered? I imagine that would be something to be done on site?

    1. Ralph,

      hello again my friend. The soldering of these parts has been a tricky affair. We went with silver solder as it melts at high temperature, which will mean that the solder stays in place during the powder coating process. The higher heat for the solder has made it tricky to put panels together without warping as the copper sheet is relatively thin.

      After the parts are powder coated, any further soldering would affect the black finish, so my plan is to use some combination of copper nails, copper rivets, and construction adhesive to attach certain copper fittings. This will be done in the shop, as I plan to go to site with the copper feet mounted.

      Only the copper feet for the rear support posts wrap all around the posts and will have an exposed seam, so those pieces really are the only ones needing further mechanical connection at the seam. The feet for the main posts terminate at the seam for the flanking post on both sides, and will be held with hidden clips. The caps for the stiles will be held with some combination of copper nails and construction adhesive. The main post caps will be fixed with decorative bronze nails like you see on the door fronts.



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