Saturday, May 14, 2011

Coffee Anyone? (5)

Post 5 in a build thread describing the design and construction of a coffee table having a bubinga frame and legs, a glass top, and a frame and panel shelf below. Previous posts are located in the archive section to the right of the page. If you're new here, or haven't visited in a while, here's a link to -> post 1 <- in the series to bring you up to speed.

In the last post I showed the first set of steps in processing the cuts for the joins on the table's shelf frame. Those cuts then finished out with a bunch of chisel work. First the stub tenon trenches get their sidewalls pared:


Then some clean out with the 5mm bench chisel:


Finishing with some work with the 5mm paring chisel:


Here are a couple of frame members, set down so you can see the male and female halves of the joint in relation to one another:


Note that the female half in the above photo is turned upside-down in relation to it's partner.

These two sections are then slid together, and the following few photos show the actual assembly right after the cut out work has been completed, with no adjustments to fit yet undertaken:



Here's a look at the underside of the connection as it comes closer to full engagement:


The fit was tight and my pecs got a bit of a workout sliding the parts together!

Top side again, joint halves now together fully:


There's a residual pencil line on the miter which may make it look like there's a gap at the back corner, however I think the miter will draw perfectly tight. I spot a light gap at the front corner in the above photo, but I think that will go away once the wedge clamps it together. If not, then I'll need to do a very slight paring cut with a plane. The joint halves connect so as to leave a flush top and bottom face to one another, which means I don't have to make any adjustments in that regard.

Front face - note the slight apace allowances at the end-points of the stub tenons, a gap of about 0.005":


The gap allows the miter faces to be drawn tight without bottoming out on those stub tenons.

The underside:


Then a check with the combo square to see if the joint is aligned at 45˚:


It was looking satisfactory at that point, and my somewhat fussy work in the jointing and cut out stages had produced a result that went together with no further adjustment required. That's the ideal at least, and I can't always say it works out so well, but it did this time!

This success in the miter fitting continued a while later, as I had a couple of the sub-assemblies, the end portions of the shelf frames, assembled up with the same fit quality as the first two pieces:


A few more sessions of chisel work and I had the long frame members ready to attach, and did so, forming the stretched octagonal framework of the table shelf:


Another view:


Overall, the assembly went together very well, with perhaps a very slight amount of paring needed down the line to get the cumulative miter joints to form a 'perfect' 360˚ when all together. I imagine the miters at the moment are within a tenth or two of a degree out of 45˚, so there are only a few minor pares required. That will happen when I complete the cut out of these joints - there are wedges yet to be fitted, and those will mechanically squeeze the joints up tight. I'm thinking I'll wedge up the pair of joints on each end assembly and then fit the long frame rails on, checking them for parallelism, and making any needed adjustments only on those miters between the long rails and the end sub-assemblies.

I snapped a few more photos of the frame after I had it all assembled up, so I may as well put them on the page, even if I risk a certain amount of repetition. Here's the underside of one joint:


Another view:


Front face and miter of the same joint just shown:


You can see my pencil lines are sometimes a bit off the actual cut lines. I set the pieces in jigs for the table saw and routing cuts, and this exposed some irregularities in the location of my pencil lines. I hadn't overly fussed that pencil layout, as I knew in the layout stage that I would be processing most of the primary cuts using fixing jigs - still, I was a little surprised at how far away some of the lines were from the actual cuts. It all boiled down to the first crosscut on the table saw which established a reference surface on the joint- the location of that cut, which was sighted by eye, led to the variance, along with the inevitable slight variances in the layout itself. I didn't really need to layout each stick's joinery to such an extent, but I wanted to be totally clear on which end was which and which was up and down, so I just laid them all out. In the end, the use of fixturing jigs meant that each piece was produced so as to be identical in length and location of abutment surfaces, so that is what counted, not the location of the pencil marks.

At this point the shelf frame members are mostly complete. Next, I have to make the dovetailed batten that connects the middle of the long rails to one another, and I'll be using a wedged dovetail for that connection (a slight change from what was drawn). The locking mechanisms - shachi-sen - have to be fitted to the corner miters yet, and then the dado for the panel will be cut all around. Finally, there are the housed joints where the table legs connect, and the moulding of the front faces of the frame to be dealt with. I now have the custom shaper cutters on hand for that step.

I've obtained a new finishing product to test out on some samples. I've been looking for an alternative finish to the Tung Oil and Waterlox finishes, something with low or non-existent VOC's which dries in a fairly timely manner and forms a tough surface. I have found such a product from a relatively local firm, Vermont Coatings. They make a finish based on a cheese-processing by-product: whey. It looks promising and judging from the photo gallery I've seen on their site, it appears to be an attractive finish which doesn't build up any kind of a plastic-like coat. It's absolutely non-toxic. So, I'll make some tests on some Wenge and bubinga samples in various combinations, and see what happens. The company sent me free trial samples in satin, semi-gloss, and gloss to experiment with. I'm looking forward to seeing how this goes.

All for today - thanks for dropping by the Carpentry Way. Comments always welcome.

9 comments:

  1. Fantastic work & joinery Chris. Looking forward to the report and photos of the new finish.

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  2. Thanks Dale! Hopefully I'll manage to take photos of the different finishes that will be reasonably informative and show the differences clearly.

    ~Chris

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  3. You always use such interesting and neatly executed joints. Fabulous!

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  4. Julie,

    you words are most kind! I can only claim to be following the examples set forth in Chinese and Japanese joinery practice, and there is always more to learn in those areas.

    ~Chris

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  5. Nice work, Chris, bordering on sashimono. You are a real perfectionist, it is a admirable quality when just about the whole world is telling us, "faster and faster". The top looks like a nice proportion, as well.

    Curious about your contemplation on something however. The visual consideration of having the degree of end grain exposed, along with the likelihood that wood movement is going to give some changing discrepancy in the elevation between the end grain and where it meets the sides of the top, any thoughts?

    As you know, sashimono pretty much regards exposing end grain as an undesirable, hence the hidden joints that are utilized. Pretty darn subtle and exciting, like zen in the wonderment of not knowing, i.e., the beauty of 'nothingness'. It is very quiet. You seem capable of that approach as well.

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  6. Dennis,

    good to hear from you. The question of whether to expose end grain or not is, I find, a tricky one to handle. Unlike in Japan and China, there is scant awareness in the West, it seems, of the higher-class nature of pieces which are joined so as to expose little or no end grain. That said, I'm not so sure many in Japan or China, these days, have much of a clue about such matters either, though there certainly was much appreciation for it at one point in time.

    And, the consideration for whether people 'get it', or not, should not really inform my decision about how to make the piece, as that should come from a decision about what makes sense structurally and aesthetically, in terms of assembly method, and in terms of the budget.

    Undoubtedly though, higher class work means concealed joinery in so far as possible, and the understated elegance that inheres to that approach. I'm in total agreement with that.

    I will make one comment about sashimono work - for all it's elegance and sophistication in concealing the principal joinery, there is the counterpoint to be observed, more often than not, of the exposed wooden pegs holding the drawer sides to the fronts and securing the drawer bottoms and cabinet backs in place. Not the most elegant work in those areas, and I've always found that a little odd frankly.

    Here where I live, virtually every client I have had, when given the choice between a joint where the mechanism is completely concealed, and one in which it is more obvious, chooses the joint where the mechanism of connection is more obvious. So, that is one thing I keep in mind.

    In this culture, joinery sophistication is generally lost on most people, and even most woodworkers, I would suspect, if they saw a plain mitered joint would naturally assume a biscuit, dowel or similar was glued in and holding things together. People would almost never suspect ingenious joinery concealed within, and a significant portion would be puzzled at why anyone would do that anyway. So, the sense you have of the hidden joint being "subtle and exciting' - - while I also feel the same way, that is not how most others are feeling when viewing such a construction. What's the value of conveying a subtle message if virtually no one picks up on it? Sure, for my own satisfaction as a maker, but is that all?

    part 2 to follow...

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  7. Continued...

    In this case, the client did not direct me in regards to the joinery specifics - they were more interested in form and function issues and other decorative details. So, it's up to me to decide how to detail the joinery, a freedom I do enjoy, but which is a point of much careful consideration too.

    In most of the framework of this piece, such as the upper frame, the miters joining the frame members will reveal nothing about the joinery mechanism. It could be doweled or biscuited together for all anyone knows (which, of course, it most certainly will not be!). The connection of leg to upper table is concealed using, well... you'll see later on in a subsequent post. The connection of leg to table shelf reveals two small pegs, one of which is fairly discretely tucked in behind the leg's rear face. I could have done those connections with hell tenons (fox-tailing, for those readers who might wonder what I mean), or a glued-up housed cogged joint, but I like something which is demountable (= easily repaired) if need be, and pegging makes that quite straightforward to realize.

    And then there's the shelf. I have a middle batten which could have been pegged and through-tenoned into the surrounding frame, or through-tenoned and then wedged on the outside, however it will be done blind, and wedged from the inside. So that joint is concealed.

    For the shelf's corner miter joints, as described above, and as you observed, I have decided to reveal a bit of end grain. The wedging mechanism will also be visible. Yes, I could have chosen to join it without showing any end grain or mechanism, but I didn't. If nothing else, the choice I have made on the shelf frame corners clearly shows, or at least hints at, that this coffee table is a piece of joined furniture. Further, the exposed joinery on the polygonal shelf serves, along with it's shape, as a sort of counterpoint to the ellipsoidal upper table frame with concealed joints.

    Everywhere else on the table except for the shelf and I have restrained myself in terms of the joinery, letting the form and the material take center stage. That's a risk I take - hopefully the form and finish on the wood will shine through enough.

    I hope the reasons for my decision make good sense to you.

    ~Chris

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  8. Very informative reply, thanks. You always seem very conscious of your decisions as how to construct things, though you usually don't mention the degree of contemplation that goes into it. i suspected that you had your reasons for the type of joinery after weighing some options, so I was curious about it.

    I think that 'restraint' in design is a quality that has been much more completely realized in the east, and it gets pretty complex when you undertake a study of why that is, with the distinct cultural differences that cause people to minimize their personality in their work, or be more inclined to want to exert it. With woodworking, either way you go presents challenges, and there is the element of the public's taste, that you mention. Oddly enough in Japan, I would say that the more concealed type of joinery is less dictated by the public's appreciation for such, than the craftsmen's own ideology having grown to that point, a sense of fashion of a high order, so to speak, much influenced by teachers and peers. Long apprenticeships tend to make for a somewhat stricter approach.

    There was a period when sahimono really outdid itself, some phenomenal work, Koda Himi being one craftsman in particular that seems almost to have been beyond human. Even in what had been the rather private world of the craftsman artisan in Japan, exhibitions few and far in-between, no doubt that people were somewhat influenced by what was going on in other shops, certain standards of the day. You see that even in the work of the 'Living treasures', now deceased. Considering their clientele, patrons really, they were much working for a very select few.

    For some reason, in particular, subtlety in woodwork is one of the more obscure motivations for woodworkers in the west. I believe that you tend see it more in some other fields of endeavor, such as weaving and glass work, a few potters around that have been influenced by the eastern aesthetic. Jim Krenov, having known him, a man not short on having a rather strong personality himself, i thought did make a great contribution to broadening the awareness of subtlety, by pointing out that the wood has a voice in the matter of design, and one need become sensitive to that. Probably few if any had said that before in the neck of the woods where he ended up. It seems to have been a message that was quite well received.

    End grain can be quite beautiful, and that is generally how the scientists tell with exactitude what species they are looking at, if there is otherwise indecision about it. How much to utilize it when designing? It seems that every craftsman is entitled to their owen ruminations about it, and sometimes also being aware of a few guidelines from the way people have looked at things in the past, is a helpful little tool to have in your kit as well.

    I bet that you are enjoying working on the coffee table.

    Regards.

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  9. Dennis,

    I very much appreciate your input and engagement on this topic!

    I think you're right that Krenov's message was quite well received - I know I was definitely influenced by "A Cabinetmaker's Notebook".

    ~Chris

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