Friday, October 13, 2017

MFA Kabukimon Redux

It has been a couple of years now since the kabukimon for the Tenshin garden at the Museum of Fine arts in Boston was completed.

Here's a reminder of how the original gate looked, after 25 year's service:


The old gate's wooden elements sat right down at ground level, and the main posts were supported by large steel plates front and rear. The wood under those plates - indeed, all of the wood at ground level, was considerably rotted, as one would expect. The door frame parts were completely rotten as well, as was the main cross beam, or kabuki, as it had a stress relief kerf running along the upper surface open to the weather. At some point there had been a piece of copper flashing face-nailed onto the beam, but it had evidently blown off in the wind at some point in the past without anyone noticing. That made for a convenient point for the entry of water as you may well imagine.

Additionally the old gate was constructed quite extensively using plain metal rods, lag bolts, and so forth, and their corrosion made for both difficult disassembly and extensive staining in adjacent wood areas. The combination of the metal fasteners, poor flashing, and placement of timbers right at soil level meant that in the end I was unable to recycle any significant amount of material from the gate. Anything that was free from rot tended to have oxide stains. That was too bad.

So when I had the opportunity to redesign the gate, I pushed long and hard for a roofed gate instead of a kabukimon, as a roof greatly extends the lifespan of the wooden elements below. In then end, for reasons I won't get into here, the decision was made to replace the gate with one of the same type, however they did agree to foundation improvements which would bring the wooden parts up and off the ground. The construction of the gate, and subsequent installation occupied many posts here at the Carpentry Way over the winter of 2014~2015. I'll forever remember that winter, given my unheated shop, as it was the winter of the 'polar vortex' and my shop was incredibly cold for an extended period.

Here's the gate at the time of the opening ceremony and dedication:


Sharp eyes will notice many differences in proportion between old and new. These changes were not arbitrary, or made blindly. The old gate had kinda weird proportions compared to classic forms I have studied, and my design is much more aligned to the classic form of kabukimon, not that the design of gates as such is something set in stone and can never be varied.

Note that at the bottom of the posts are black 'shoes' which are pieces of copper flashing. These are there in effort to simulate the appearance of the black metal plates on the old gate, however I had argued against putting them on at all, as they do not enhance durability in any way. Rather they trap moisture. Similarly, I argued against the use of decorative nails on the faces of the door and flanking section panels, as I knew that seasonal wood movement would persuade them loose over time. Indeed, on the old gate, many of these decorative nails had fallen out and had been lost. Though they listened to my arguments, in the end I was asked to put the 'shoes' and the decorative nails on the gate.

I don't make the above observations to say "I was right and they were wrong", but rather to point out one of the things I learned through working with a large institution: mine was one voice of many, and though "building it to last", "wise use of materials", "sustainability", or "building it right" might seem like darn important things, in the bigger picture they often get steamrolled over by other concerns from other parties. Those concerns might be real or they might be imagined, and they are often political in nature, but they carry weight all the same with those tasked with making final decisions. Greater weight than my arguments anyhow.

So, last year, many of the decorative nails were coming quite loose and falling to the ground, being removed by patrons, lost in the grass, etc.. They let me know about it and I obtained a hundred more decorative patinated nails and their caps from Japan, and put replacements in for the ones which had been lost. However when doing the replacement I filed notches in the nail shanks and put a dab of construction adhesive on, and this seems to be keeping the replaced nails in position for the time being. A year later they remain in place.

Last year, the rear gate posts had swelled more than expected and the sheet copper 'shoes' were wrecked, so I replaced them with 2-piece shoes to accommodate the amount of movement that was taking place. These have worked well so far.

This year, one of the wettest in this area for many years, one of the main gate posts swelled some 1/4" in width and this wrecked the 'shoe' on the bottom, necessitating its replacement. Maybe I could have foreseen this, but really, it was more than I expected. Again, I came back with a version of 'shoe' flashing composed of multiple pieces to accommodate the greater-than-expected movement.

The other main gate post, while it has swelled some amount, did not swell nearly so much as it's partner and the copper 'shoe' there is doing fine for now. Also, both posts have only swelled at the bottom, where the effects of precipitation are the slowest to pass. The copper caps atop the posts remain undisturbed by wood movement it would appear.

So, here we are replacing that post 'shoe' on a fine day in Boston::


I apply some construction adhesive to the inside corners, so as to fix the copper piece to the arris of the beam, allowing for wood movement therefore at the middle of each post face:


Tapping the first piece into position:


I made an exact replica of the post's lower end for the copper fabricator to fit pieces to, and as a result the fitting on site went without a hitch:


Tapping the hinge fixing pin an its escutcheon back into place:


Then some decorative nails, notched and with a dab of construction adhesive, are tapped into some pre-drilled holes:


These connections will accommodate about 1/2" of post movement on each face, far more than it should ever see.

As mentioned, the flashing on the other post was doing fine, which was a little odd to me since the post on that side was far more unruly in its movement during the cut out phase than the one which had done all the swelling:


A few general pics from around the gate now. I'm pleasantly surprised at the good overall condition - it's weathering nicely:


All the framing joints remain nice and tight. If it weren't for urban grime generally, the gate would be a lot cleaner in fact:


The benefit of hand-planed wood is clear, when you run your hand along a weathered piece and it still feels quite smooth and does not evidence raised grain:



A pleasant visit concludes:



All for this time. Thanks for visiting the Carpentry Way.