Monday, January 19, 2015

Gateway (36)

Post 36 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.

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I think I could have been a bit clearer in regards to the mortising work seen in yesterday's post. While I can explain that I am mortising for the stretchers, or nuki, that doesn't mean of course that all readers will immediately realize to which components I am referring.

Nothing like a picture then to clarify the matter. The nuki, in red:


Given that the rear posts are wider apart, the nuki angle outward from the front posts; furthermore, the upper nuki are compound angled as they also slope down from the front posts. Those pieces will be processed into a parallelogram shape in the next while.

Today, among other things, I completed work on the lower mortises - the joints here are a wedged half dovetail:


A wedged half dovetail joint like this goes by a couple of different names in Japanese. One term is otoshi-ari-hozo-shiguchi, another is sa-ge-kama tsugi. and another is kata-sa-ge-ari-tsugi. I'll spare you a terminology overload and just call it a wedged half-dovetail, okay?

I was an insomniac last night, not dropping off until 3:00am or so, and while I lay there thinking over the myriad details of this project, it occurred to me to re-check how these joints would fit together on the drawing as I suspected I might have some interference issues, and as a result this morning I discovered a slight adjustment to dimensions was in order. The mortises needed to elongate by 1/8" and the upper wedge needed to get 1/16" taller. Minor changes, but good to figure out now rather than later.I love CAD drawing for this very reason - it helps you see things that otherwise would be easily overlooked or misconstrued.

When I got to the shop I set to work completing the end wall chop out on these lower nuki mortises:


 I took a couple of videos while I was at it and this is the result:


I'm glad so many have shared with me that they are enjoying these videos, however it's not likely I will manage to provide them with every posting. It takes a lot of work and time to edit the content and put together a video, then hours for it to finalize and load to YouTube. I'm starting to get a bit better hang of it now, so definitely expect to see video clips more often, just not every post.

In other news...I noticed my narrow ō-tsuki-nomi had a chunk out of the edge, right into the ura:


Not sure how that happened, but it was from paring - perhaps I ran it into a knot.

Normally I do not bother tapping out chisels, however in this case I will:


Will flatten that out and refresh the bevel tomorrow morning and see how it looks.

In other news...I machined the kerfs open on the inside faces of the main posts and fitted umeki:


Then out came the heating blanket:


Today it was a balmy 4˚C in my shop, which really didn't seem too bad at all.

Also sliced up some of that recently-received 2"x4" POC stock to make the infill strips for the front faces of the posts:


I anticipate completing all of the remaining infill work tomorrow. It's just those two main post faces to take care of now. I hope the detailed explanations of the process and the explanation about how one deals with various situations through these past few posts has been helpful. There remains a little umeki work to do, not involving the stress relief kerfs however.

All for today - thanks for visiting the Carpentry Way. Post 37 anyone?

4 comments:

  1. You 'normally don't bother with tapping out'? What do you do, take it off the back?
    I'm a carpenter who has been using Japanese chisels for 20 years or so, and have tapped out a few as they shorten.

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    Replies
    1. Jonny,

      in case it wasn't clear, I meant that specifically in regards to chisels. Plane blades are another matter and must always be tapped out at the edge gets down to the ura-suki line. Chisels do not fit into a wedged slot, like a plane blade, so the simplest way of dealing with the edge getting down to the ura is to re-flatten the back. The penalty for this is that the hollow gets smaller, which means that the amount of cutting steel to be worked flat gradually increases over time. For smaller chisels this is not of much consequence. Larger chisels, especially ones with a long blade portion, like the slick, should be tapped out I think.

      Thanks for your comment.

      ~C

      Delete
  2. Hi Chris

    Just wanted to join those saying thanks for the videos. It really adds another dimension (no pun intended) to your explanations.

    Glad to hear it's getting warmer over there. Are the mortises for the nuki angled or are you shaping the tenon? I cannot tell from the drawings.

    Cheers
    Sebastian

    ReplyDelete
    Replies
    1. Sebastian,

      thanks for the comment.

      As noted in the text above, "Given that the rear posts are wider apart, the nuki angle outward from the front posts; furthermore, the upper nuki are compound angled as they also slope down from the front posts."

      Hope that clarified the matter.

      ~C

      Delete

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