Dark Chocolate and Sponge Cake (11)

Amazingly, to me at least, the last post in this series occurred on March 29th of this year. Where did all the time go? Well, that’s easy enough to answer – most of it went into the project work at Colgate University, and then a few other things came up. I had thought I might be away from this piece for a 2~3 month stretch but somehow more water has passed under the bridge than that. That’s how it goes.

So glad to be back on this project, and ready to dig into some more of that delicious Cuban mahogany. The parts previously cut have been sitting in my shop, strewed around somewhat as I juggled other parts from various projects, and now that I dust these pieces off I am pleased to find that the mahogany, of both varieties (Cuban and Honduran) has remained perfectly stable. The joined frame joints remain tight and clean, and the panels free of warp, bow, cup, or twist. That’s a benefit of having the parts ‘season’ in the shop mid-construction. The Cuban mahogany has oxidized a degree back to a chocolate color, so I feel like there’s no need to worry about applying dye to freshly cut sections to blend parts together for color/tone -it will all look uniform after a few months so I’ll make the piece intending to celebrate the variegation, knowing it is but fleeting.

One of the lessons that has come to be clear to me in recent years, when faced with a situation where a project is interrupted for a lengthy period, is that it sure pays to be doubly cautious when re-entering the fray. One can’t always step back into full flow and take up as if there has been no interruption, for as much as there has been a time break there has also been a mental one. Caution is merited on account of the precious nature of the wood I am working with, the supply of which really does not allow for those sort of mistakes which would necessitate that a stick or panel be replaced. But the other caution flag which comes up for me now relates to that getting one’s head back into the project and not making assumptions about next steps until one is thoroughly back into the very head space which shaped where things had been taken to in the previous design and build phase.

On top of all this are the factors which come up when you look at something with fresh eyes again and may well choose to do some details differently than previously envisioned.

Assumptions can be a real drag sometimes if they do not prove to be correct. Every woodworker knows this, and I would venture to say that making erroneous assumptions is one of the most common sources of error in projects, along with plain old inattention and/or obliviousness.

When I start in on a drawing for a project, I tend to work first in big (digital) brush strokes, coming up with appropriate massing and configuration for the piece to suit the intended purpose. Once I have shared these initial ideas with a client, the direction forward hopefully becomes more established, and eventually I am rendering the piece in fairly close detail.

I say ‘fairly close’ detail rather than ‘exact’ detail because, with more complex pieces especially, certain areas of a drawing such as joinery details (if they are not a visual feature), or uncertainties about the final form of a molding profile, or any spacing/number errors which may crop up in SketchUp drawing that indicate there is a problem somewhere (a problem however which would require significant backtracking and analysis to parse out), tend to be left for later. In such cases I tend to continue forward with the sketching of the piece, the goal being to produce a drawing which conveys all of the visual detail the client needs in order to make the decision to proceed.

Others might only take their drawings as far as the concept sketch phase in their interactions with their clients, but I find that with joinery-based solid wood pieces a lot of the constructional detailing is going to be apparent in the final product, so it makes sense to define it fairly thoroughly so that the rendered drawing is very close to what will be made. The look of the piece comes partially from how it is made, not from what is applied to something otherwise to make it look like something it really isn’t.

Once I have reached the ‘go-ahead’ phase with the client, wood and other materials are sourced and I go about producing any necessary templates I might need. Once the wood is in hand and ready to be worked, I start breaking down the material as per a cut list, prioritizing the critical pieces first. When it comes time to cut joinery, I go back to my drawing and go over the component in question with a fine-toothed comb looking to correct errors, flesh out details, make minor changes as required.

So, at this phase, I grab rendered components in my drawing and duplicate them, and then in the same sketch make the duplicate white in color so that I know it is a revised and ‘final’ part.

After a while the overall sketch becomes cluttered with various components which have been dragged out, made white and revised to a detailed level. My main drawing looks like this right now, for example:

Sometimes I put things on different layers, toggling layers on and off, but I don’t always bother with that for single pieces of furniture.

I also start new sub-drawings dedicated to particular aspects like doors, back panel framing, drawers, etc., copying parts over and then going through them in detail, again rendering to white. Once the part is finalized in the drawing I print take-offs of various parts and their details, with dimensions, which I then take with me to the shop. It’s like a road map. Until recently we have not had a family laptop, so taking the drawings to the shop has become what I am used to, as opposed to keeping a computer at the shop. My shop lacks an office or dust-free space, so I tend to be averse to bringing a laptop into that – and my wife certainly is not keen on that either.

And, where I last left off in the build I had just started the fabrication process with this futon storage cabinet, having prepped most of the stock, and having constructed the frame for the top and the 4 sets of latticework which comprise the sides of the cabinet:

I could have re-started pretty much anywhere, but I chose to continue on with the fabrication of the top frame and panel. So far I have prepped the stock, cut the corner joints, cut the interior edge dado for the panel, and molded the outside. See post 6, post 7 and post 8 if your memory needs refreshing. I know mine did!

The frame of the top has the thickest section height of any stick in the cabinet, and I was only able to squeeze out the four frame members I have from the 8/4 stock I obtained. There were only two boards out of the pile which yielded material of the required thickness, so if something goes south with joinery cut out on the frame, which is a bit on the complicated side so it is rife with opportunity for errors, then I have nothing with which to replace it. It’s not like I can go and get some more Cuban mahogany at the hardwood lumber outlet. So, I’m super careful. Well, a bit paranoid too! It seems that you can’t so freely use the term ‘it’s only wood’ when what you have to work is in actuality virtually irreplaceable.

One of the tricky areas with frame and panel work is that of joining the frame outer corners together with their supporting post. The three way connection in other words. There are various solutions of course, and I’ve wrote about them extensively in the past, and I have written two joinery Monographs which deal with this topic exclusively. Yet, with a new project comes new particulars, and I sometimes need to come up with new configurations of three-way connections to satisfy the requirements. I find this a lot of fun actually and relish the challenge.

Just in case it might not be clear, here’s the connection I am using in this cabinet to join the top’s corners and posts together:

It’s a form of half lap, but one which needs to incorporate the size and position of the post tenon amid the lap’s dual locking pin mechanism, shachi-sen, plus accommodate the molded front profile, and the interior dado for the panel. Pushing the design configuration is the intended assembly sequence involving the latticed side frames and bottom frame. Also pushing on the design is the fact that the post tenon’s visual exposure means that the position of the rear post tenons need to be the same if at all possible to the front tenons, and yet the form of post used at each location is different. The rear posts accommodate the clip-in back panel assembly, while the front posts are shaped to partner with the door stiles in such a way so as to allow the doors to swing 180˚ open. Finally, there was the design decision to use a joint which showed a bit of it’s mechanism, instead, say, of a joint with a fully mitered appearance. This decision was made in light of the piece overall and wanting to walk that fine line between showcasing the material and showing the virtues of joined work too. The corner joint with shachi sen is becoming a frequent feature of my work, part of the design language.

So, there’s a lot going on in a tight space and a lot to consider. Of course I fully recognize that I do bring this on myself though the desire I have to build, insofar as possible/reasonable, without any recourse to glue or metal fasteners and using joinery which is, to whatever extent it seems sensible to push it, demountable. It would all be vastly simpler and quicker, to be sure, to join everything together with glued butt joint and miter joint connections with dowels, biscuits, dominoes, etc., and maybe even tack on a little joinery simulacra. I’ve seen in some pieces of furniture the look of through tenons simulated by simply burning rectangles on the surface for instance. How these pieces are not outright laughed at and withdrawn from consideration for sale at the furniture outlet is beyond me, but of course there are price points to consider. Anyway, I’m not tempted by those easier routes though it certainly offers what it from many sides a more pragmatic way to proceed, that is, from a manufacturing and profit/loss perspective.

Anyway, back to the top frame detailing. The relative simplicity of the core of the joint, that of half-lap pierced by single tenon, appealed to me, but wringing out the details took a while. I think that’s one of the key things to realizing a design successfully: sitting with the design until it is truly done to the last detail and not giving into the strong temptation to just get on with the cuttin’. Sometimes those little tiny details that seemed better to gloss over, the ones your choose to mentally abbreviate, can come back to bite you – this certainly has happened to me enough times.

When I got my head back into the drawing after the long break, I discovered that I had left off working on the drawing in the middle of finalizing certain details. Some things were not pencilled in fully, and some parts were annoyingly off their marks for reasons which were unclear. About three days were absorbed in straightening everything out and getting to a point of being ready to fabricate.

Back then to the cutting, I decided to mortise the lap joints for the tenons, and thought it made good sense to mill these mortises with the joints tightened and in an aligned position. In the past I have tackled such joints with chisel alone, by hollow chisel mortiser, and by router with edge guide. Now my weapon of choice, more often than not, is the Zimmermann pattern mill. I’ve gravitated, therefore, to the tool that tends to produce the most precise results, with the safest way to produce the cuts, with the cut area clearly exposed to view, the cleanest way to produce the cuts, and with the most reliable fixturing. That, in a nutshell, is the pattern mill.

I used a pair of Bessey clamps to dial each corner joint in tight and dead square, before clamping the assembly down onto the work table of the mill:

The mortises had been marked out months ago, but a last double check revealed one of the mortises was in the wrong position (!), so I’m super glad I took the time to re-check that and make the correction.

The mortise is roughed out initially with a under-size cutter and the location of the mortise defined by that cut’s position checked with a caliper in situ:

The 0.5mm pencil lines get me within a couple of hundredths of an inch (0.2mm or so) of where I want things to be, and the ‘mill an undersized hole then check with caliper’ approach allows me then to get very close to the desired position. Cutting the parts together in one fixturing assures the best chances of alignment between mortises across the lap, while cutting them separately does tend to invite greater error.

After making any required positional adjustments, I next place in the collet a slow spiral down-shear finisher bit to clean the mortise out to finish dimension, plunging down in stages until I am within a whisker of the table surface:

After the milling, I clean up the mortise ends with some chisel work:

Two separate set ups on the mill were used to do the four corners of the frame, and those four little mortises took me close to 5 hours to do. That’s a crazy long time for mortises to be sure, but I couldn’t mess around when the material doesn’t provide spare parts and the exposure of the tenons right at perfect viewing height means the mortise openings cannot have any defects.

Here’s one pair of connections:

Long frame rails on the bottom, the short sides stacked on top.

Here’s the other end of the pieces:

The outcome of these joints, I think, presents good example of the advantages to be gained by thoroughly working a given drawing through to a more refined level of detail. That will become more apparent later on when you see how the post connections are detailed.

While there is more cut out work to do on these four top frame members, I will set them aside and keep the train going in regards to the corner lap joints overall, four more of which are employed on the cabinet’s bottom frame. As it is, the remaining work to be dealt with on the upper frame (mortising for the cross-pieces) is also required on the lower frame, so it makes sense to do that work later on on both frames at the same time. The corner joints themselves are not completely the same on the bottom (given differences in assembly requirement, molded profile, and sectional size), so that cut out work was not tackled at the same time as the cut out of the corner joints on the upper frame. It all makes vague sense to me at least! When you’re not producing in quantity and you tackle all the parts yourself, I tell myself is okay to jump around a bit, even if that same voice inside me questions if I am tackling production in as logical a manner as possible. Probably not, but most important is to get through the step without mishap.

All for this round, and thanks for visiting the Carpentry Way! Post 12 follows.