Saturday, September 5, 2015

A Ming-Inspired Cabinet (6)

In the last post in this thread I mentioned that I had obtained some 'Honduran' Mahogany for the secondary wood on the cabinet. It was good quality stuff, but truth be told I wasn't entirely pleased with the material I received. I had wanted quartersawn mahogany, while 7 out of the 10 boards received did not fitting that description even remotely.

I realize now that quartersawn mahogany is not generally what was being cut at the mills- mahogany saw logs are invariably sawn through and through - and thus QS stock is less available than I had thought. Sawing through a log like that, you would likely only obtain a couple of quartersawn boards per log. I felt that trying to obtain more of that material (in bulk) in the hope of scoring some more quartersawn boards was not looking promising. None of the retailers I spoke with seemed even willing to do a sort for a few boards, and fair enough - though none of them seemed too interested when I wanted 150 board feet either.

After further rumination on the matter, I decided it would be best to choose a different species for the secondary wood, a species which was ideally cut for quartersawn from the get-go and which would be a good match for the bubinga used for the rest of the cabinet.

I've already considered woods such as mahogany, black cherry, and Swiss pear wood for the secondary wood. None of those were likely to fit the requirements I had in terms of grain orientation, so I kept looking.

I finally came across a suitable material, and it is botanically related to bubinga (which is guibortia tessmanii OR guibortia pellagriniana OR guibortia demeusei).

This is a wood called Shedua, aka Ovangkol, which comes from the species guibortia ehie. This is a somewhat smaller tree than those species from which bubinga is obtained. The wood comes from West African countries like Gabon and Cameroon, and the tree is more commonly utilized for its gum resin, called Congo copal, than its timber. The timber is not very commonly available, and it does seem to find a certain favor among the guitar-making community from the research I have done. Shedua should be a good match texturally for the bubinga, and that is an important consideration when matching a couple of woods together in a piece.

Here's a guitar with a shedua back:


(From: http://www.guitarbench.com/2012/01/04/shedua-tonewood-profile/)

As you can see, it has a more brownish cast than bubinga, but shares the black streaks. Comparing Shedua's mechanical properties with bubinga, it is very close indeed, being very slightly lighter and less dense, a little lower in volumetric change due to moisture content change, a slight bit softer in terms of crushing strength and a hair stiffer in bending strength (modulus of elasticity). I imagine, therefore, that it should have fairly similar working qualities to bubinga.

This image from Hearne Hardwoods shows the varied appearance of Shedua based on the grain orientation:


As it so happens, Hearne was one of the few places in the US which had any stock of Shedua at all, let alone QS and/or figured stock.

In fact, they had a decently sized stack of 12/4 material, 6~12" wide, 16' long or longer, and some of it was quartersawn. Considering few other retailers have any of this material, it was amazing to come across such nice stock. They also took time to reply to my emails, and send pictures, once I had demonstrated solid interest in the material - - and had given them my credit card info! Hearne seems to be a retailer specializing in high quality and rare woods.

They sent me some pictures of a couple of boards which matched the requirements I gave them, swabbed with alcohol to make the figure a bit clearer though not showing the tone which will be obtained with a proper finish:


They were wondering if I was so determined to have quartersawn because I was a luthier, however I let them know they were guessing wrong. I do have some specific reasons for wanting quartersawn material of course.


The guy who sent me the pictures stated that these two boards might be the nicest in the entire pile.




I asked for a follow-up pic of the end grain of the two boards, to confirm they were what I wanted in terms of grain orientation:


And the other board, about 12" wide:


The sticks are hard to scale until you notice that a forklift is doing the lifting....

The stock looked good to me. The price was steep, at $35/board foot, so each of those boards was $1400.00, however I was able to offset some of the cost somewhat by selling a portion of the previously-acquired mahogany off to another woodworker in my building.

I ordered those two boards and they should be at my shop in another 3~4 days. I think this wood will go very nicely with the bubinga used for the bulk of the cabinet:


I think the CAD representation of the Shedua is approximate at best. Definitely a bit greener than brown, however not a concern at this juncture and easy enough to correct.

In recent days I have revised the horizontal and vertical dividers on the lower bank of drawers, making them straight instead of having them match the drawer curves, and I also recessed them back slightly - this for among other reasons, to increase the shadow interplay between the curved drawers and the surrounding framework:


The divider's outer arrises will additionally be chamfered.

The drawers themselves will have a beaded perimeter detail, and have the drawer sidewall through- tenons poking out, neither of which is illustrated yet, and the handle design for the drawers remains an open question. Likewise, the upper set of drawers and doors remains just a frontal plane at the moment with no allowance for set back, chamfering, etc.. Getting there!

Thanks for visiting the Carpentry Way. Got some machine's coming soon so I am working on getting my shop ready for that - this will likely be the subject of the next post, #7.

2 comments:

  1. Coming along nicely Chris, nice choice on the Shedua stock, it is gorgeous. I'm looking forward to seeing this cabinet come to life.

    ReplyDelete
    Replies
    1. Brian,

      thanks! I anticipate getting going full tilt on the construction after the Japanese carpentry classes are over in October.

      ~C

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