Saturday, May 18, 2013

Tower of Power

My wife and I decided we wanted to grow peas and beans on a trellis. I figured I could come up with something that could mount on one of the locust beds I completed recently. After considering a few different designs, and wanting to make something fairly 'quick' and 'simple'  - those terms being, of course, relative - I settled on a pyramidal design. This meant making posts which were non-square in section, so that when on a compound slope they present surfaces which conform to the prism.

So, the trellis, made of Teak and Spanish Cedar scraps, took a few hours to construct in my shop, and fit nicely upon the planter box when installed. I nearly considered mortising stretchers in at one point, however decided to content myself with stainless screws to mount the battens to the legs, thereby forming the climbing surface:


You can see I've got a couple of pole beans started in two of the corners.

Backing the legs into the correct shape means that the battens lie flat on the leg faces - otherwise, with an un-backed leg, the shape would require the battens to bow outward to conform to the legs, or you'd have to bevel the inside face of the batten where it met the leg. The techniques of changing the legs shapes and finding the correct compound bevel angles with a framing square are standard apprentice-level projects in Japanese carpentry. One of the things I like about Japanese carpentry relative to what is practiced in other places, is how sophisticated techniques can be used to create structures which look simple in appearance. Simple lines, clean assemblies, elegance - a winning formula I would say. Not saying I achieve that, but I like the design sense and underlying methodology and strive to emulate it in what I make. That requires study and practice of course.

I was glad to revisit the geometry of the compound splayed leg arrangement with this quickie project, as I try to make something in that form every year. By now I can solve all the geometry involved without recourse to looking in books or having to scratch my head too much, which feels empowering. 'Use it or lose it' seems to hold true.

I chose the pyramidal form as it is inherently self-stable. The garden is a windy site. Before the battens were installed I was able to hang with my full body weight from the upper framework, with the feet secured from any lateral slippage, so I think it should support climbing plants well enough. The battens have their ends trimmed to be in plane with the pyramid.

The upper frame is made of teak, and uses Ipé pins. I painted the end grain to retard moisture loss:


I'm interested to see how these various materials in the garden, Black Locust, Teak, Spanish Cedar and Ipé, stand up over time and relative to one another. All of these woods are highly rot resistant and durable outdoors.

Another look:


A glimpse of the top - first time I have pinned post tenons on compound-sloped legs. I left the pins proud as trimming them was unnecessary labor in this case:


I have a couple of planter beds prepared, this one will be the 'hot' one, and has some eggplant and tomatoes now in place:


The bed with the agribon fabric cover has the leafy greens in it.

I'm in a lull between projects right now, which I'm enjoying, and now that the garden stuff is mostly done (well, I do have another smaller trellis to build yet) I'm looking forward to putting some time into developing a better website, constructing a large wood rack in my shop, moving a Carpentry Study Group project along, playing some disc golf, and maybe getting out on my bike once in a while. While 'work makes free' in this culture, a break is to be savored.

Thanks for dropping by the Carpentry Way.

9 comments:

  1. Very nice mate.

    I made some climbing frames for our garden but not as elegant as yours. I used rebar mesh painted for the infill and the same crappy cabot stain for the frames.

    The frames will be treated with the blow torch when I redo the planter.

    ReplyDelete
    Replies
    1. Pat,

      thanks for sharing and hope your sheds are selling well these days.

      ~C

      Delete
  2. I wish they were mate. Trouble is I don't have a means to build them on the West Coast (which is where all the enquiries come from) so I'm probably going to pack it in.

    On the bright side though, hopefully I'll have more time to devote to Japanese carpentry.

    ReplyDelete
    Replies
    1. Pat,

      just a suggestion: why not configure the sheds as a kit so that the buyer has to install the foundation and then you come and install or provide the kit so that they put it together?

      ~C

      Delete
  3. That was the original idea. The problem being that I have to ship out to the West Coast and that adds a considerable amount to the cost.

    The solution would be to move west and I can't afford/don't want, to do so.

    ReplyDelete
  4. I wish I could solve the geometry of the backing so quickly. I always have to go back to a book. Do you have any suggested reading for the Japanese solution? I always go back to old American or British carpentry or roof framing books...

    ReplyDelete
    Replies
    1. Steve,

      Thanks for your comment and question. I own or have looked in most of the old American or British carpentry texts and the topic of backing a tower or spire post is very poorly covered. In all cases, they only deal with backing the front surfaces and not the inner ones, which makes adding stretchers with through tenons more of a PITA. And then one finds that they don't seem to make much mention of doing joinery with such backed posts.

      Any basic Japanese text on carpentry layout covers the topic, however if you want to read about the methods with the convenience of the English language, then I would suggest you consider my series of layout books, The Art of Japanese Carpentry Drawing. Volume IV covers splay-legged post work, however if you are unfamiliar with Japanese method generally, you will need to start with volume I and II, which introduce the topic by way of the hopper. Drop me an email if you are interested in these Volumes. There is nothing else remotely as detailed on the topic outside of Japanese-language materials.

      ~C

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    2. I would be interested in your volumes, I will email to follow up.

      I can remember now finding the backing angle for hip rafters by making a level cut on a scrap of wood and sliding it over the edge of the top plate at 45 degrees. Draw a line on the bottom side of the level cut where it hangs over the plate and this was the backing cut....the rip that was removed from the top was nailed to the under side of the hip for drywall backing.... but no understanding of the math here, just fast framing.

      Delete

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