Friday, April 8, 2011

Building Up My Library

I have been chipping away, literally, at the 'quick and dirty' bookcase project, which I am making from Canary Wood (sides, top and bottom), Black Cherry (shelves), and bubinga (frame and panel back). I thought I'd post up a few pictures of progress on this piece as at least a couple of readers had indicated interest in seeing this piece go together.

With the jointing and planing steps out of the way, I started in on the joins which put the shelves and case sides together. At a minimum, these need to be dadoed joints given the significant weight of the books. If this were truly a quick and dirty job, say a built in bookcase or other storage for the landlord, something he keeps after I move out, and he isn't willing to pay for anything beyond materials, then I would get some poplar or pine, dado the case sides and screw the shelves into place. That would be the absolute minimum grade of work. It's sound and strong, but not the sort of thing to put in a furniture gallery, if you follow.

Here, given that this is not a built-in but a free-standing piece of furniture I will take with me when time comes to move next, and given that I'm using better quality wood, I need to do a bit more than dado and screw joins. Now, that might be a case of plugging over the screw holes, but I'm not going to be using any metal fasteners. I intend to use the absolute minimum of glue, and being a case piece it will not be possible to avoid glue altogether. So, the choices narrow...

To join the shelves to the case sides, I could employ housed tapered dovetails, however this piece has sides which are on the slender side, and to use housed dovetails would mean that the dovetails would be really scant in height, like 1/4" or so, which would be weak, or the dovetails would be made taller - which would mean that the case sides would be perilously weakened by their mortises. Therefore I have chosen to use multiple mortise and tenon joints, four per shelf end. The shelves and case bottom will be housed in 1/8" and the tenons put right through the board, then double-wedged on the face side.

After marking out both case sides, I used a router to cut the housings at their target depth:


The shelf heights are graduated, with the tallest books being accommodated at the bottom of the case.

Unlike past projects, I have chosen not to draw the piece ahead of time or work out any details in advance. I'm going against my nature and working things out as I go, making decisions on the fly. I'm not setting a new pattern of work, just trying something a little different than usual.

A close up of one of the shelf dadoes:


Both case sides now roughed out:


Another view, where the rebate for the frame and panel back can now be seen more clearly:


The shelf boards were next. I trimmed them to length, checking carefully that they were squarely cut. Then I processed the four tenons on the end of the boards:


Next, you can see in the photo that I have also diminished the thickness of the tenons by rebating the board ends cross-wise, just 1/16" each side.


A look at the tenons a little closer in:


Let's see...four tenons per board end makes eight tenons/board, multiply by 6 boards receiving the tenons, and we end up with 48 mortises to cut! Funny how the math works out sometimes.

I make the cuts initially with the router, as this tool, with a spiral carbide bit, can burrow right through and out the backside of the board without any of that unpleasant tear-out.

Then it was time to clean the mortises up the usual way:


A little while later, the mortises were squared up in all 48 locations:


A closer look:


Not close enough for you? Well, how about this?:


Next, the electron-microscopy, for a truly close up view:

Just kidding!

So, next step with these mortises is to chop the end walls at a slope to accommodate the wedging. A little trigonometry determined that the end wall slope in the mortise needs to be 7.125˚. The same block I used to chop the mortises at 90˚ has that 7˚ slope processed on the other side, so I will be tackling this step next time, with a freshly sharpened chisel.

Once the mortises are done, I will have 96 saw kerfs to do in the tenons ends, and 96 wittle widdly wedges to make up. A little tedious to be sure.

I still haven't settled on which joint I will be choosing for the connection between the top board and the sides. I will continue to mull it over.

Thanks for dropping by the Carpentry Way today. Comments always welcome. --> On to post II

3 comments:

  1. Hi Chris
    Interesting projest. I wonder how the kerfs will be cut in the tennons, I'm thinking they will be Horizontal so as not to split the side pannels.

    ReplyDelete
  2. Hi Gordon,

    you are seeing it quite clearly: for the reason you mentioned, the kerfs will run horizontally.

    ~Chris

    ReplyDelete
  3. I like your quick and dirty project

    "Clean the mortises the usual way" I checked for a hollow chisel mortiser , OK there is a range problem, unlike your new drill press.

    Being cheap, I once measured a set of hole saws to see if the interior of one saw matched the exterior of another to make an even quicker and dirtier shelve with round tenons, but I had no luck yet.

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