Saturday, November 14, 2015

A Ming-Inspired Cabinet (8)

While I started out with what was an enormous slab of bubinga, the sheer volume of wood does not correlate strictly with usability. I am preferentially using quartersawn or rift orientation throughout the cabinet(s), and that is where starting with a large bubinga slab afforded some options in grain selection. Once I had cut out the desired cants from the slab, I was left with a large remnant, namely the middle run of the slab. It is about 1/3 of the original width, and is a piece which is almost entirely flatsawn. A chunk like that is of far less general usefulness to me, though I do anticipate making use of it in this project. The flatsawn portion just does not convert in this case into wide pieces of stock however, just narrow and/or short pieces.

The two thick quartersawn cants I obtained from the slab were therefore precious, pretty much irreplaceable really, and it is from these two cants which I am intending to recover the panels for the doors on the cabinet. Those two doors are bifold in design, and therefore 4 panels are required. A 3" thick slab will re-saw into 4 pieces of about 0.75" in thickness, all being well. I say 'all being well', as this is a step carrying certain unknowns. I've had pieces of bubinga which, after having been re-sawn from a thicker cant, proceeded to become very unruly in their behavior and impossible to keep flat. It's a shame to take a board which is flat and perfectly usable, then re-saw it and end up with a bunch of scrap. It just can't be predicted what will happen, not with any certainty at least.

When re-sawing, stresses are released from the board. Some of these stresses are present as a result of the growing conditions the tree underwent, and some of these stresses may have been induced through a imperfect drying process. A piece of wood can be dead flat and look promising for re-saw, only to have boards go spriong! after cutting and you are then left with a whole bunch of nothing. Re-sawing is not a complete walk in the dark: the grain orientation of the board, along with its position in the slab, and therefore in the tree, are useful telltales as to how it might behave when sawn, and certain things can be anticipated.

In this case, having two quartersawn cants and needing to obtain 4 flat boards from each after re-sawing (given that I am making two cabinets in total) left me with no wiggle room whatsoever. No boards were permitted to move more than about 1/8" after cutting. It was verboten, and I made sure the cants were clear on this before undertaking any more work on them.

Well, in truth I did have an additional cant which was there as a back up for the panels, however I very much preferred avoiding having to cut into that spare piece since it had other vital uses on the project. I needed all the wood I can possibly convert out of the stock on hand, and as it is I had to drop another $1800 today to obtain 3 more wide quartersawn boards from Rare Earth Hardwoods in Missouri. These come on the heels of 3 long and wide bubinga boards purchased from the company last year, material which is also going into these cabinets.

These cabinets are positively going to devour material! I find it amazing how much can disappear into a piece.

In general, the safest re-saw cut is to divide a board exactly in half. This should distribute stress release equally to both pieces, and all being well, one will emerge after cutting with two flat boards. And, if the wood movement is severe after the initial division in half, then you will have a good idea of what lays ahead - i.e., more movement-  and can perhaps plan accordingly. That's a good time to head to the bar I suppose, or your wood therapist.

The initial slice and dice of the slab, detailed in the previous posting, was the first step in the process, and I let the recovered pieces sit a couple of days in my shop. No significant movement was noted, and so I proceeded to do an initial re-saw on each cant, dividing each into two boards about 1.5" thick. That also went successfully.

Today I decided, upon inspecting the re-sawn material and finding it flat, that I could tackle the next step, which was to slice each 1.5" thick piece into two boards. That process began with a pass or two on the jointer with each board:



I had meant to film the entire re-saw and the 'reveal' afterwards, however the camera ran out of battery charge.

The resulting boards, shown at the end of the above video, are worth another look:


Can you believe this stuff?! Nature is amazing!

The set of four sawn out of the other cant:


I was greatly relieved to have obtained full value from the re-sawing, and the material looks terrific. Think how it will look once there is a finish on there....

Currently, the re-sawn material is very flat and a full 1/4" over finished dimension, so I am feeling confident about having made it through this stage without incident. I was stressed but the boards were not. While in each set two of the boards appear to look really figured and two do not look quite as figured, this is simply an optical effect relating to camera position. If I shifted camera position a few inches left or right in each case, the figuring effect would shift to the other two boards in each set. It's fun to walk along and look at the boards and see the figure shimmering about as different portions of the grain reflect.

Onward and upward...thanks for visiting. Post 9 is next.

7 comments:

  1. I'm glad you made sure the cants were clear on what was expected of them. :)

    Looking forward to this build! Along the way, could you say a few words on how you decide to orient the panels to use the figure? I lean toward having the grain flow all the way across the surface, rather than book matching and having turn on and off depending on viewing angle... but I still don't appreciate all considerations that go into the decision, especially not with such gorgeous bulbinga!

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    1. Jamie,

      I've found the cants are very good listeners, and never argue with me directly.

      I look at grain orientation primarily from a few different vantage points:

      -the grain orientation with minimum propensity for movement
      -the grain orientation which will facilitate planing
      -the grain orientation of vertical pieces will match the orientation of the pieces in the standing tree

      For these panels, I sliced cants from both the left and right flanks of an enormous slab with a centered run of grain. It was clear therefore which end of the slab was the top of the tree, and which face of the cant was towards the outside of the tree. I marked the cants accordingly before slicing them out.

      Now, each cant has been cut into four boards, and each set of 4 has fairly similar figure. Each face of each board is marked so I know which face of the board is facing towards the bark, and which end of each board is towards the top of the tree.

      Next, I will take two boards from the left set, and two boards from the right set, and combine them to form two new groups. In this step I can aim for an aesthetically pleasing pattern across the four board faces as they relate to one another. I will have pairs of boards on each side of that grouping oriented in respect to one another as if they were in the tree - i.e., the two on the left will be from the left side of the slab, and the two on the right will be from the right side of the slab. I will also end up with all the boards oriented as they stood in the tree, and facing the same direction, and this should mean all the boards plane the same direction and reflect light from their figure somewhat similarly.

      ~C

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  2. I'm so glad I asked -- thank you! I can see how milling up boards from a slab makes all those design considerations possible/more straightforward. Great to see those machines in action.

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  3. Hi Chris,
    Are you able to figure out what was the top of the tree in more heavily processed boards? Or is it somewhat necessary to have the giant slab to give you a good idea. I'm turning it over in my head as to possible different heart/bark/cathedral clues but I'm getting a little lost. Any tips or tricks to determining that would be appreciated! I also saw this mentioned in a japanese joinery documentary on youtube where they said door parts might be less likely to warp if left in their natural orientation.
    Thanks,
    Owen

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    1. Owen,

      appreciate the question.

      When I started with the slab, I was able to tell from a look at the end grain and the faces of the board which end of the slab was towards the top of the tree and which was towards the bottom. It wasn't too hard to do since the tree trunk the slab came from was slightly tapered and the sapwood tapered out towards zero at the bottom of the slab. I then marked the ends of the cants I ripped and cross cut out of the slab to indicate which end of each piece was top. I keep an eye on this throughout the processing work so that when I am done the boards are oriented as is preferable.

      Japanese practice is to use material from a tree as it came from the tree itself. This is done not only in respect to top/bottom, but to even which portion of the log was south facing, north facing, or, if using material from many logs in a building, one would take logs from south facing slopes and put the timber from them similarly on the south side of a building, etc. Then there are practices for dealing with placing timbers in a building relative to which portion of the tree they came from and the effects that location in the log will likely have on reaction wood and future movement - placing timbers thus obtained in a structure in relation to one another so that the reaction wood or movement propensities of different sticks are cancelled out by one another. There's more to this topic yet, perhaps something to elaborate on in a future blog post.

      ~C

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  4. Hi Chris,
    Thanks for your response. I love learning stuff like this... so much more beautiful than chopping everything into 2x4's and building matchstick houses :-/
    I bought my first Kanna over the holidays from someone who had scooped up a bunch of old tools at a garage sale - and while I was optimistic because it seems quite old and the steel seems very, very hard... good lord it's been a can of worms. Probably not a great beginner kanna as it's a 70mm blade. (I mostly only have krenov style planes I made myself, and 2" is my largest). I pulled up the "kanna help you" articles, and started nervously correcting the twist - but got into flattening the back, needing to hollow it out more, and eventually felt a little overwhelmed and just put it down. There are a few other issues I'm not too sure about. Not giving up yet, but realising it is going to take me a lot longer than I anticipated...and I didn't even have any illusions about it being easy!
    If you are interested, I was wondering if I might send you some pictures - I fear I have made a mess of it so far, and would really like to salvage it. Or maybe you would take one look at it and tell me I have a scrub plane or wall art.
    Thanks as always for sharing your work, it's truly inspiring!
    Owen

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    Replies
    1. Owen,

      sure, send me some pictures and I'll take a look. At least it was a garage sale find and a therefore good and inexpensive tool to learn on whatever the outcome.

      ~C

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