Tuesday, December 30, 2014

Gateway (22)

Post 22 in an ongoing series describing the design and build of a Japanese gate for the Museum of Fine Arts in Boston.


After yesterday's adventures, I had some time to think about the apparently moist interior of one of the beam chunks I had sliced up. It was seeming a bit grim frankly. I began coming up with a few plans as to how to best proceed, generally along the lines of cutting the joinery parts over/undersize, and letting them dry for a few weeks, perhaps even returning the pieces to dehumidification for a spell. None of which was at all what you might call convenient. Just cutting the joints though in green wood is a formula for loose connections and poor fits later on, and I didn't want that.

So when I got to the shop this morning, the first thing I wanted to do was assess how moist the parts were. And you know what? They weren't moist at all:

Must have been a hallucination on my part. 12% MC at the core is perfect. The wood is evenly dried. Whew! That was a load off my mind, let me tell you.

Okay, back to it. For the next while everything I will be dealing with will be big and heavy, so good thing my back is feeling healthy. Those core exercises seem to be paying off. Today I started in on cutting the main crossbeam, or kabuki. The process is similar to that undertaken with the nose pieces yesterday: careful layout, double checking layout, double checking drawings and looking at layout one more time, and then out comes the Makita 380mm saw:

I prefer this saw to the more commonly available 405mm version they sell in the US, which has a crappy stamped steel base. While the same 405mm saw can be obtained from Japan with the better cast base, I feel the 380 mm saw is a better match for the 110v. motor. It's a sweet machine and highly accurate.

Crosscutting is followed by ripping, using the same 50T blade, and off comes the waste:

I immediately shoved the moisture meter pins in there to check - again, a pleasing result of 12%:

That's such a relief.

Next task was to mortise the beams for some long tenons. I dusted off my Makita 7305L beam mortiser, which hasn't seen action in far too long. I fitted the 30mm chisel and started cutting. Here's a video showing a cut:

With the first bit of mortising, the stress relief kerf in the timber was in an inconvenient place which made it a problem to run two rows of mortises side by side. You can see in the still photo above that the first mortise was started, and then had to be abandoned. So I ran it down the middle and then used the circular saw to rough cut the outer walls:

I followed the same process on the other end of the kabuki, then did the same thing to the two nose ends, where I was able to use the double row of mortises, which vastly cut down on the work required to remove the waste later on:

A closer look:

A 30mm chisel run down in two rows side by side means a 60mm width is mortised, just inside of the target of 2.5" (63.5mm). Convenient - I wish I could say I had planned it that way, but it just worked out 'tis all. I wish the mortiser could cut a little deeper, but 155mm (6.1") deep is a good start at least.

A lot of chopping and paring lays ahead on those parts, but I put them aside for the time being as my neighbor Joe showed up, who was, it turned out, persuadable in terms of helping me schlep a couple of larger timbers over the jointer and through the planer. I promised him beer, and duly delivered afterward. I may have understated the nature of the task, but he was game.

Before the fun could begin, I first mounted an Aigner extension on my jointer outfeed table:

You can see that the bar has 4 mounting holes. It came with two holes. The factory ones, which are anodized, happen to be in a position such that a hole drilled through the table edge would run right into a casting web, which would be highly undesirable - there would be no place to put a nut onto the mounting bolt. I hate shit like that. So I had a local machinist make a couple of new holes in the mounting bar. I wish Aigner would supply a bar with no holes, or supply one just to fit Martin jointer tables. Oh well.

Anyway, it took all of 5 minutes to drill and mount the bar and extension table:

With the extension in place, I end up with a fairly long jointing surface:

A bit more than 14' (4.3m) in fact:

It was very helpful to have that additional support on the outfeed, as we were jointing 8"x9" (205mmx230mm) timbers, 10' (3m) long. They weren't light, not in the slightest degree.

After a bunch of grunting, snorting and other manly stuff, you know, we had a pair of clean and square timbers - these are going to be the rear support posts for the gate:

It's nice to have a planer and jointer which can handle these sort of tasks. I've tackled this job in many different ways in the past, but will choose to run the material over stationary equipment any time it is feasible to do so. My body can just manage the task - Joe was looking decidedly hunched and creaky afterward, though the beer seemed to perk him up. His help was invaluable.

The rear support posts, by the way, will be parallelogram-shaped, so the above milling was simply the initial step. I'll let the parts sit for a week and then tackle the phase 2 milling.

Tomorrow I'll be digging into the main posts. The last day of 2014 should be a fun one, with more timber 'rasslin' ahead.

Thanks for dropping by the Carpentry Way. Comments always welcome. Post 23 up next.

Monday, December 29, 2014

Gateway (21)

Work on the kiosk continues. One of the interesting aspects to this project, I find, is that of trying to replicate the aesthetics of the previous gate, and part of that aesthetic involves the connections between parts. The old gate was fastened together primarily with threaded rod and somewhat simple (in my view at least) joinery. I won't be building the new gate with the metal fasteners or the crude connections, wanting to bring things up a notch (heh!) - however I will be seeking to duplicate the clean connection look that you get with the hidden metal fasteners. As a result, I have to keep the pegging and other overt mechanisms somewhat on the down-low - by which I mean, concealed, hidden, discrete.

In fact, I will be using few conventional pegs at all on this project.

Case in point is the junction between the kiosk's crossbeam and the repair posts. While it would be quick and expedient to fasten the post to the beam using a housing and some timber screws, I have decided to use my own variant on a joint the Japanese call hiki-dokko. Forms of this joint are going to be used in many places on this project.

These are the housings on the splice-on post sections to carry the crossbeam:

The housing is stepped, as you can see.

The mortise carries through to the inside of the scarf and there is opened up a little to form a pocket:

A closer look:

It took most of the day to complete the fabrication, and in the end it was time to see if this will all come together. Here are some of the main parts:

I made the draw-bar out of a Burmese Teak offcut. It slides in first:

Then the crosspiece fits to the post:

Once the post and crossbeam are together, the draw-bar, a variant type of yatoi-sen, is tapped in:

The sloped head of the yatoi-sen is recessed into the scarf to accommodate some shrinkage, should it occur:

On the business end, it will connect the crossbeam using a pair of tapered locking pins, or shachi-sen:

A gap is necessary at the end of the yatoi-sen to accommodate the tensioning process when the shachi-sen are driven in.

Both posts now assembled to the cross-tie:

This method of joining the parts takes the joinery mechanism and hides it by placement on the underside of the crossbeam.

It took a bit of wrangling, but a while later the post-assembly was united with the kiosk:

One side closer in:

The other:

As the shachi-sen are not installed yet, much less fabricated, the joint is not fully drawn up yet. There is enough friction between the pieces to keep everything together just fine though. I have to disassemble these connections later on when the metal shoes are complete and can be fitted.

With the help of a couple of concerned citizens, I moved the kiosk to another part of the shop and stood it upright:

Another view:

Right, onto the main gate fabrication.

First task was to start cutting the nose pieces for the main crossbeam, or kabuki:

The cuts were completed down to the mark with a handsaw.

With a little powerlifting action, the large Hitachi bandsaw was brought into play and the waste portions were removed cleanly:

After cutting I discovered that these sticks were slightly damp on the inside, so they did not get fully dried right down to the core. That was after 6 months of dehumidification, so I'm thinking that a year of dehumidification might have been best for these chunkier bits. But a year of drying time, well, that I didn't have anyhow, so it was the best that could be done. It would have been good too if the sawlogs in question hadn't been sitting on the ground in Oregon for so long....

There are things you can control, and things you can't.

All for today - thanks for coming by. On to post 22.

Friday, December 26, 2014

Gateway (Twenty)

With the post title I decided to jump away from the Roman numerals at this juncture, as I think after a while a lot of folks are going to possibly find the numbering more confusing than helpful. If not, and you are choked that the Roman numerals are no more, you have my deepest apologies. Onward we march....


Work continued today on the kiosk post splice repairs. First job was to buck the posts pieces down closer to finished size, which removed a good 20" from each piece. That made them easier to handle.

After a bit of faffing about with fitting the posts in a horizontal position, I decided that it would probably be easier to tackle the fitting with the posts vertically-oriented:

In most cases, when post rot splice repairs are undertaken, either you are working on a complete structure, which has been jacked up and you fit the repair post in from below, or the structure has been completely disassembled and you are working on the sticks individually. Here, the structure is all together yet it is sufficiently small and awkward to handle that I ended up working on it in this manner. Like I said, splicing on new to old material has its challenges.

I started getting the splice on one post engaged:

At this point, about 1/2" (13mm) shy of closure:

Another view:

Since the main portion of the joint has sloped surfaces, as the joint goes together it tightens up. It is important to judge the fit carefully, as it is inevitable that when the surfaces finally come all together you will need to make some final tweaks. If the joint was put together from too far apart with too much force, then it can be kinda hard to separate again. Conversely, you don't want to overcompensate in the direction of easing the fit either as the joint will then be a bit loose when fully up.

Second post now fitted to a partial engagement:

A closer look - about 1cm apart at this point:

Getting closer with additional fitting work:

A bit of trimming and uttering and muttering later, almost there:

Another view after another whomp with the mallet:

Purty dang close....

I chose to drive them all the way together, and then found some areas that needed further fettling, and then pulled the joints apart. A while later, adjustments complete, the connections were reassembled:

Let's see how things look:

 Front face:

Shop is looking a bit like a disaster zone at the moment, but never mind that.

The other front face:

Looking passable for sure:

Closer in yet:

You will notice that the new wood piece is a bit larger than the old. Does this imply that I will be be planing the surfaces of the new piece down until they are flush with the old one? No.

One of the lessons of Japanese temple carpentry that I am working to understand better and incorporate into my work is the attention paid in the framing process to how things will be 10 or 20 years down the line. Wood and wooden assemblies, shrink, settle, weather and distort over time. Making things when new to fit crisply is all very well, but if 10 years later the settling and shrinkage of the material causes large gaps to form in those formerly tight joints then the carpenter has failed to anticipate. So, the trick is to understand what is likely to happen (and this will vary in different parts of a structure depending upon exposure to the elements, local climate, and how much live/dead weight is involved) and design the connections so that after the settling and movement has concluded the fit is good. This may mean that new pieces will be fitted to their neighbors with slight gaps in certain areas. Looks like a mistake was made, but it isn't the case.

The old wood posts in this kiosk have shrunk and distorted and settled after 26 years outdoors. That wood has done most of its moving and weathering by now. The new piece needs to be left oversize as it is likely after 10~15 years of weathering and adjustment it will become more nearly similar to the piece to which it connects.

Further, the post will join to a metal shoe down lower, and needs to be square in section at that location. If I made the new post identical in shape to the old one, I would have to make it non-square in the spliced area as well, which would then leave me with the task of feathering out the faces from non-square to square in a run of about 20 inches. I'd rather not.

Finally, if one planed the new material down to match the old it would be difficult to do so without kissing the old wood surface with the plane somewhere. Then one would be left with applying some sort of stain to try and blend the parts, never mind the change in surface from weathered to planed, and it would be tricky to pull off the transition cleanly. As it is, I'll be looking to stain the new wood to look similar to the weathered material. I'm hoping my contacts in the finishing industry can give me some good advice as to how to accomplish that.

Funny enough, the splicing repair was likely the trickiest joinery work on the entire project, so I'm glad to have gotten through cleanly. Everything from here on out is joining new material to new material, everything straight and square, which is so much more straightforward. For the kiosk, I've marked out for the cross member location and milled up the stock for that, so tomorrow I plan to complete that portion, which will wrap up the kiosk repair work for the most part. When the metal shoe fabrication is complete in a few weeks, I will return to this portion of the job and fit the shoes, re-establish the electrical chase up the back of one post, do final planing, chamfering and so forth.

Thanks for coming by the Carpentry Way. On to post 21.

Thursday, December 25, 2014

Totally Flakey

Not much in the way of snowflakes around here right now, so I thought I'd look around elsewhere. Where else but Japan would you find such creative truss framing?:

It seems obvious to call it a snowflake truss, which would be yuki no kesshō in Japanese (雪の結晶) because that is what the form of which it reminds me. It's the new community center building in Toyooka City, located in Hyogo prefecture:

Very cleanly done framing as you would expect - also making use of local materials:

It was designed by a guy name Misaru Tahara. I'd be really interested to see the structural analysis of this truss, to see how it apportions loads.

It's beautiful in any case:

Another view:

It cleverly combines Japanese traditional framing, using nobori-bari 'ascending beam' (also termed ne-magari-zai 根曲がり材, literally 'curved root material') from the tops of the wall, and a framework that is otherwise stark and geometrical in form:

Opposites attract, and are attractive.

Another view:

I'm sure there's some metal in there somewhere, especially where the connected elements are in tension.

I imagine you saw this here first, no? The center for breaking news, 24 hours a day....

Well, not quite.

Merry Christmas from the Carpentry Way!