…...bird, that is. This was an interesting project from several perspectives. It began when my son-in-law, Jordan, asked if I would help build a birdhouse to enter in a contest at his workplace. Since Jordan is a structural engineer at an architectural firm, I suspected the entries wouldn't be your run-of-the-mill back yard birdhouses. If we wanted to compete, we knew we had to take our game to the next level. We had to consider the design, material, aesthetics, usefulness from the bird's perspective, and ability to withstand weather. We both wanted something that was practical for the birds, plus had a chance of at least placing in the competition (note that a lot of the entrants are primarily interested in winning, and the poor birds be damned). Google was put to work and we found lots of interesting designs, which of course we wanted to tweak a little.
First we had to choose the material. During my last trip to the lumber yard, I had seen some kayu batu in the corner, and had picked up a few planks. I didn't have anything in mind, but it was reasonably priced for an exotic and I wanted to see how it responded to hand tools. It's commonly used for decks, and has a reputation of lasting forever out in the weather. This seemed like a perfect project for the kayu batu. The planks were almost 5/4" thick and 5 1/2" wide.
Design, construction techniques, joinery, etc, were topics at the center of a lively debate. We settled on a design that is somewhat similar to the final product (not exactly, because we ended up "winging" parts of it, har har). We purposely violated some woodworking rules in order to achieve desired looks and take advantage of the material at hand. Of course, we had to compensate for our violations in other ways.
The primary rule we violated was in regard to the dovetails. The tails and pins were not aligned with the grain, which is flagrantly breaking a rule and compromising structural integrity. We did it for three reasons: 1) we wanted the look of hand-cut dovetails, 2) we did not want the end grain to show, and 3) we could utilize the planks with the grain running up/down without cutting them down or gluing up panels.
We compensated by doing our best on the glue-up with waterproof glue, then ran a bead of epoxy paste on the inside of each joint. Result? The look of hand-cut dovetails, efficient use of materials, and a box you could run over with a truck. This is built like a brick ...uh…. Bird-house. Not that other four letter word you are thinking, get your mind out of the gutter!
To start the construction, we first re-sawed the planks and milled them to final thickness. Final wall thickness is a hair under 1/2". We did get some cupping after a day or two, but nothing the hand planes couldn't take care of. Next was hand-cut dovetails, the entry hole was drilled, and the back was shortened at the bottom to allow a sliding floor to go in/out. Then on to the glue-up with Titebond 3, the waterproof stuff.
Next, I epoxied in the four posts to support the roof and added a fillet of epoxy paste to each of the four inside corners. Mortises about 1/2" deep were chiseled into the bottom of the roof. The roof is two full-thickness pieces that are edge-glued together. It is tapered about an inch from front to back on each side, with an overhang of 2" at the front and about 1 1/2" at the back.
After dry-fitting the roof, I decided it looked to heavy and added the curve to the top, using a cambered-blade jack plane and finishing with a smoother. It looks better and will help it shed water. Gotta love design features that look good and are also practical. The roof is attached with epoxy paste.
The finish is watco oil, and I also soaked the end grain with epoxy and put epoxy on the bottom of the roof. I did not put epoxy on any areas that are exposed to the sun, as UV rays quickly destroy epoxy. The reason for the epoxy on the end grain and bottom of the roof is the wood developed several checks after final milling, and I wanted to do something to keep them from growing.
This is the guinea pig first-build, and it's one I will keep. Jordan is also building one, and finally we'll build one for the contest, which will be auctioned off to support wildlife groups.
How does kayu batu respond to hand tools? Overall, I like it. It is a bit brittle, but it doesn't really splinter. It planes well, as long as your blades are sharp. A little tearout, but it's controllable. I didn't use my toothed blade, so it's not that bad. Scrapers work wonders on it, I did not have to sand anything, see the curlies below. Grain is ruler straight. My understanding is this is a farmed, sustainable wood, so no rain forests were logged.
Here's a pic with the roof dry-fitted and no finish.