Thursday, June 9, 2011

Coffee Anyone? (7)

Post 7 in a series describing the design and construction of a coffee table, the frame and legs of which will be make of bubinga, along with the shelf frame. The shelf panel is to be wenge, and the main table top will be glass. Previous posts in this thread can be found in the 'blog archive' to the right of the page (not visible to you if you are using a mobile device or Google reader).

I've been making steady progress over the past while, though this project has been somewhat on slow mode in the past two weeks as I have been waiting for the CNC work to be done. That was scheduled to happen on the 16th~24th of last month, but there have been delays for a variety of reasons - I'll not get into that here. Today I received a message from the sub-contractor that the cut out has commenced on the table top frame members, which are of semi-elliptical plan. Here's a sneak peak of a test piece - the piece's front face now profiled (it's upside-down in the picture):


The cut quality looks excellent from the picture at least. Hopefully, these frame pieces will be done tomorrow, and the legs are scheduled to be done about a week later.

In the last post, I had moved the locking miter joint joinery along for the table shelf. The next order of work on those parts was to mortise some of the pieces for pins which will secure drawbars connecting the frame to the legs:



Pin mortises cut on a couple of frame pieces now:



With all four complete, I moved on to mortising for the drawbars:



As a general rule, I always mortise for pins first.

The draw bar mortises roughed out:


 
I then used a router to dimension the mortises for width. This was followed by cleaning the mortise end walls to the line with a chisel and guide block:



A cleaned out mortise, albeit with some kuzu in the bottom:



Next step was to use gauge blocks, 0.5"x 0.75" (the exact size required) to test the fit, followed by cleaning out and trimming as necessary:



Once the fit of the gauge block was decent, I tried the fit of the drawbars, which are just slightly fat for the hole, by about 0.002" or so:



That made for a decent fit for those parts.

A short while later, all 4 were done:



These drawbars will be fitted into corresponding pinned mortises on the legs, and that is how the shelf and leg lock to one another.  Housings have yet to be cut on the above-illustrated pieces. The connections will be done without recourse to glue, as has become my habit of late.

Another task on the list was to mortise the long side frame rails of the stretched octagonal shelf unit for the shelf batten's male half-dovetail tenons. Again, the hollow chisel mortiser got the ball rolling, this time with the aid of the machine's table being tilted:



The roughed out dovetail mortises:



Again, I used my router to clean the mortise side walls to required point.

Then, out come the chisels, along with an angled paring guide:

 

That's those two out of the way, though I can see they still a little loving yet in a couple of places with a paring chisel:



 Next it was time to move the Wenge panel along a bit, working the top surface over with my plane:



Then I made up a jig and routed the backside of the panel for the sliding dovetail female - starting with a first set of passes to rough out the trench:


 Then the trench was trimmed down to the right depth, and brought into the dovetail shape:



The tongue is still a little thick in the above picture, so...

...then I completed the trimming of the tongue around the perimeter of the panel, first working on the router table and then some final clean-up to dimension using a shoulder plane :


I've been doing some tests on wood samples with Vermont Coatings whey-based finishes, and so far the results look pretty good. It dries quickly, in about 2 hours, is virtually non-toxic and odor-free, and doesn't darken the wood as much as Tung Oil does. I'm not sure though whether I want to have the bubinga kept light or not. I might prefer a darker overtone to the bubinga, and use the whey-based finish on the shelf panel. I can also use a mix of the two (I've done tests and they seem compatible), strating with the Tung Oil and finishing with the whey. I'm not quite done with the testing yet.

All for today.  Comments always welcome. Thanks for coming by!  On to post 8

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