There are some jobs that must be done as you go along; they will be very difficult to do once the back frame is glued up.
Unfortunately, I am one of those people who must see results and can’t wait indefinitely to see a frame going together. Apart from the fact that I think someone said “A decision deferred is a decision well made” I have two excuses for this less than grown up behaviour.
a) Sanding every square millimetre can be pointless if it turns out that there is a final curve or detail to be removed at a later stage, when it is more appropriate, and the offending rough piece that you have just spent ages polishing up will be removed.
b) If you only do the jobs that you have to do as you go along I think there is less opportunity of making a mistake.
For example; If I was cutting out all my mortices with a mortice machine that had taken some time to set up, I would do them all at once. In this project I have to use (and set-up) another jig for cutting the angled mortices so there is no advantage in cutting them all at once.
Next I prepared the components of the back frame. Rounding over the backs of the legs from the seat up must be done before gluing up (spokeshave and sandpaper), smoothing off the back rails and carving the lower rail cannot be left either.
It was when I was carving the lower rail that I learned about the usefulness of “out-cannel chisels”. There are both “out” (bevelled on the outside) and “in” in Mr Wake’s toolchest and I found one that exactly matched the bump in the middle of the detail in the lower rail and discovered that I could get a “factory finish” with it, after bow-sawing the bump to a rough shape.
All the curves had to be brought to a pre-sanded finish before tenoning and gluing and this was when I found out that the smallest spokeshave is not just “for small jobs” as I think I said earlier. It has a very tight throat, making it perfect for finishing; it takes off very fine shavings and can be used over large curved surfaces despite the fact that it is small.
In the drawer beside it, however, was an ugly, hand-made spokeshave that I had ignored up till now because it looked so crude; I should have learned from earlier experiences. I picked it up a few days ago, sharpened it and knew within minutes of using it that it was an essential part of the spokeshave family. It is the “scrubplane” equivalent. It has a curved blade and is ideal for ripping off large amounts of material in the early stages of forming a curve. I used it a lot as I sorted out the components; getting the curved shapes right before smoothing and tenoning the ends. The roughness of these handmade spokeshaves may be intentional as they are less inclined to rotate in your hands.
I fitted the tenons making sure that the depth of the mortices was greater than the length of tenons. You may laugh but you won’t even raise a smile if you don’t check this, and when you come to gluing up, one joint will not pull in! Less fundamental, but also worth watching, I was careful to fit the tenons in such a way as to leave my 2mm margin in front of each rail; I had to shave a good bit off the back of each tenon to achieve this, and checked from time to time with the roofing square on the bench that the joints were coming in square.
Finally I gathered up some clamps and packers, put glue in the mortices and a little on the shoulders of the tenons, pushed it together and clamped the frame up. I checked that the joints came together perfectly (sometimes this was just a matter of moving the packers around to align the pressure from each clamp to the best position for pulling in each joint.)
Moving swiftly back to the desert island; the palms, the waves breaking on the shore, the monotonous sunshine and the toolchest spilling its contents provocatively on the golden sands. What if I had all this but lacked the detailed drawings to make a chair? What is crucial to this design?
I think it is three angles that make it unique;
a) The 1 degree taper on the inside of the front legs,
b) The 13 degree “inside leg” of the back legs,
c) The 7 degree splay of the seat.
The rest you could make up, but without a protractor I’m afraid you could be deviating dangerously from tradition and who knows where that might end.
The side rails are all about these angles – there are two adjustable bevels in the toolchest – I set one at 13 degrees and the other at 7.
The top rails are angled at 7 degrees and 90 degrees. I tenoned them and fitted them dry, as with the front frame, to get the best fit for the lower rails.
-- Allan Fyfe, Lethenty Mill Furniture, http://www.lethenty-mill.com