A Japanese timber framed garden shed

[GRadice]

Getting maybe a little off track but while I'm working on the ridge beam to barge board joinery I'm considering adding a gegyo, 懸魚, which is a decorative pendant that covers the end grain of a ridge beam or purlin and hangs beneath the barge boards. The feature is called, for interesting historical and etymological reasons, a"hanging fish."

August 2009 – Page 12 – The Carpentry Way

The gegyo can be either simple or elaborately carved. Generally they have a hexagonal central feature but the surround can be pretty wild. There are many variations.

:<<>>: JAANUS :<<>>: Terminology of Japanese Architecture & Art History

Since I'm making a humble garden shed, I'm leaning toward a simple gegyo, maybe something like one of these from the internet:

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[GRadice]

I decided to make a sample/template of the barge board joinery to make sure I really understand the layout. I did a smaller scale version of this last summer but of course since then I forgot how I did it. When I do it for real it is serious since the clear vertical grain cedar I'm using for barge boards is spendy for me and I'd really like to not make mistakes. So I glued up some scraps and milled the composite to real life dimensions to make some trial barge boards. Here is the joinery from the back partially assembled.

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And from the front partially assembled. I have not tapped in the tapered locking key since once it is in, it is really difficult to remove and I'm not done yet.
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I got the angles spot on but I made a couple of mistakes. One is that I missed that the groove for one of the tongues should stop short of the edge. Otherwise it leaves an ugly gap. Fixing it makes more work on sawing out, but do-able.
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The other is that somehow on layout I underestimated or mishandled pencil line on the upper/closer edge.

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But overall the roof angles are spot on so I can use this sample to help lay out the rest of the roof.

[woodPixel]

I've seen this joint. Its diabolical.

When modelling it in Sketchup and thinking how it might be made, it seemed to be easier to make the main joint first, ensuring it fits perfectly THEN making the locking key.

Overall I then thought that draw-boring it would be SO MUCH easier

[GRadice]

I've seen this joint. Its diabolical.

When modelling it in Sketchup and thinking how it might be made, it seemed to be easier to make the main joint first, ensuring it fits perfectly THEN making the locking key.

Exactly right. That is the best way, because that's how I did it!

I wasn't exactly sure what dimensions to use for the stub tenon(s) so I just went ahead and layed out a guess on the back of a barge board and started chopping. I quickly decided that those little vertical wings were going to be a problem and probably not necessary so I didn't finish chopping them out. And I decided that my 10 mm stub tenon would be better at 15 mm, which meant I had to raise the location of the slot for the sliding dovetail by 5 mm as shown by the pencil lines.

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After making those executive decisions I took a deep breath and layed out then cut the corresponding joinery on the end of the ridge beam.

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I'll do the other end tomorrow.

[anc001]

My only requirement was that I over-do it.

I never knew I had a twin brother!

[GRadice]

I never knew I had a twin brother!

Fist bump.

I've been working on another project (Japanese timber framed bird house) for a friend so not much to report on the shed. But here is an update on the pups:

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Willa is now 17 weeks and Stella just turned 9 yrs. Amazing to get them both smiling for the camera. They are another reason I don't have much progress on the shed.

[GRadice]

Well, it is still timber framing, with joinery similar to the shed.

Port Orford cedar frame and panels, black locust barge boards and Osage orange ridge cap. All are rot resistant. Plus a few brass bits.
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[GRadice]

And I'll add that the birdhouse was bartered with a friend for more black locust wood (Robinia pseudoacacia) to use for wedges and pegs for the garden shed because it is hard and rot resistant. Seems a fair trade whatever the birds think.

[GRadice]

Back to the shed. I have the ridge beam pockets for the rafters almost all chopped out. Hand saw, chisels, and a little router cleanup. I made a rafter template to check the angles and fit. My new shop dog is not impressed. I'm hurt but but she's cute so I'll let it go.

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[GRadice]

Back to the shed. I have the ridge beam pockets for the rafters almost all chopped out. Hand saw, chisels, and a little router cleanup. I made a rafter template to check the angles and fit. My new shop dog is not impressed. I'm hurt but she's cute so I'll let it go. For scale, the rafters are on 1 ft centers because of my roofing materials available over here (OK, 304.8 mm) and are 50 x 65 mm in section.

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[GRadice]

Got the king posts done. Although these "king" posts measure a whopping 445 mm shoulder to shoulder. Nothing complicated but I did have to make sure that I got the tenons on the two ends of each post sorted into top and bottom since they face in different directions. And the shoulder to shoulder distance had to be right on to elevate the ridge beam to a pre-determined pitch. This is all basic stuff to an experienced carpenter, which I am not. So it took me a long time to check and double and triple check my measurements. But I'm happy to report that I think I got it right.

I laid them out here with the tools I used to make the tenons once I had milled the stock square. Gratuitous inclusion of the other shop dog, Stella. She also is not impressed with my efforts. Man's best friend, ha!

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I will add that one of the very simple but handy tools for this work, which I learned from a friend who studied carpentry in Japan is that little plain rectangular block milled precisely flat and square in three dimensions. Used as a gauge for the fit of tenon cheeks and shoulders. If it rocks or tips or doesn't touch at all points you quickly know where to adjust. Good for furniture sized work, too.

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[GRadice]

One of the post step tenons done. Not perfect but good enough. I test for tenon fit with a mortise template complementary to testing the mortise fit with a tenon template. Much easier than trying to test fit the joints themselves on 10 foot long beams.

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[GRadice]

Last June I ordered some more rough sawn Port Orford cedar, from the same sawmill that supplied the frame beams, for the rafters, floor joists, doors and a few other parts. The sawyer said he could get it done by mid September. Thinking then that I might be able to use it this fall I asked about getting it kiln dried instead of waiting for it to air dry. He recommended a company about 120 km south of me, we agreed, and he delivered my wood there. It took them a while to get it into their kiln because of some technical problems, but then it took only a week or 10 days in the kiln. That seems really fast to me but they said POC dries fast and stable. But then it took me a while to get down to pick it up. Anyway, I borrowed a trailer from a friend this week, rented a full sized pickup truck (Ute to you folks?) to haul it, and here it is.



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It was worth the wait. I sprung for some what is known here as "clear vertical grain" (CVG) boards, essentially quarter/rift sawn with no knots, for the doors that turned out really nice. These are twelve inches wide, 8 ft long, and 1 inch thick. (Sorry: 300 mm, 2450 mm, 25 mm). I have five of them. They will make lovely door and window shutter panels.



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And some CVG stock for the door rails and stiles. I hand planed a little spot to show the grain.



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The rest is a grade called "small tight knot", STK, which is what I've been using for the frame. Now I have to figure out where and how to store everything before it starts raining again. Gloriously dry and sunny but cool this week. It won't last. Here in Oregon it rains from November to May most days. Not a lot of rain at one time, but often.

[GRadice]

While I'm working on the tenons for the tops of the posts (three done, three to do) I thought I'd mention how I'm thinking of installing the door or doors. Probably one sliding door but it could be two sliding bypass doors.

Since I've never done this before my original thought was to follow Len Brackett's design described in Peggy Rao Sander's book Building the Japanese House Today (written for a North American audience). Here is the plan section from the book showing how the glass panel door(s) fit between the frame posts.

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And an elevation showing how the sliding tracks and sill would work:

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When I showed this design to my American guru/adviser on Japanese carpentry he said it would work but perhaps would not be as weather resistant as a design he prefers that moves the doors to an applied exterior jamb. Exterior jambs are used in traditional Japanese construction to mount amado or what we might call in America "shutters." In Japan these are usually solid, windowless or louvered panels that cover and protect the more delicate shoji panels.

Here is a video that shows how amado move on tracks and can elegantly negotiate an interior corner.


https://www.youtube.com/watch?v=XwH8-0aghgQ

My friend suggested that for my shed, I could apply an exterior jamb for the doors as is done for amado. That would help protect the shed frame and be both more more weather resistant and more readily repairable years ahead. Here is my rough elevation sketch of what he suggested.
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And how it might look in 3D

Amado shed.jpg

I'm at the stage where I have to work out the details since that will require some further joinery on the posts. i welcome suggestions and advise.

[GRadice]

All of the stepped tenons are done.

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