Your corner blocks must be a trifle broader than the ribs, and about as wide as them—also from corner to inner surface, about one and a half inches. Cut and fit these nicely for future glueing, and then prepare and bend your pine for linings. This pine must be about five-sixteenths of an inch broad by about three-thirty-seconds of an inch thick, cut to taper for inner dressing either before or after fixing to ribs. These are not too easily bent, but not nearly so difficult as the ribs; but do not put on too much pressure, or snap is the result.
It will be necessary to see carefully to the gradation of the depth of the ribs from one and a quarter inches to one and one-eighth of an inch, either when they spring from a whole length or from three separate ones. In any case, my advice is to mark the beginning and end of each section from the broad end to the narrow, Nos. 1 to 2, lower; 2 to 3, middle; 3 to 4, upper; so that you cannot well get wrong in bending, from which would spring the first cause of error.
Having your glue somewhat thin but firm, at the point of setting, glue and clamp well your corner blocks (your mould being in the vice) and after that, remove the fitted wood block over the centre rib (it being now fast at both ends by means of the blocks just glued), and accurately fit the two small linings there, removing each end of said lining between block and rib, at either end, and, by first forcing half-inch chisel where the lining will have to go, as a sort of slot. This you must also do at the ends of all the other linings. Now glue the two small ones for centre and carefully fit and force them end by end into slots, finally placing wood block [33] over glued linings, and clamp firmly with cramp [11]. The other four are much easier to fit and fix; small cramp [2] being used; but here you must always be sure of a perfect fit all over, or you will find when taken from the mould there will be apertures, Fig. 16.
| PLATE XVI. |
When dry next day, and before you take from the mould, remove most of the cramps (one or two being left to keep the work fixed) and very neatly cut and clean all the work, as shown in figure of open instrument, and go about it in this manner:—the heavy corner blocks must be reduced with large gouge, and the linings made to fall away from their full thickness at edge of ribs to fine union with said ribs at the extreme of their (the linings) width. After that, clean every atom of superfluous glue away, and finish off with two or even three courses of sandpaper, rough to fine.
Then remove these so far finished ribs, and take the knife [19], being made by you exceedingly keen of edge, and square both edges all over, so accurately that, when they are glued later on to the back and belly, they shall fit and well, being jointed so that no aperture whatever is apparent.
But, you will doubtless murmur, it is all very well to say all this—please show us how to do it all; for, on the face of it, this is no child's play. And you are right to speak out; for it is one of the most difficult points we have to master, and I fully intended to make it quite clear before leaving it.
Hold the rib by left hand firmly to your breast, face side to you. Then take the knife [19], and cut away the superfluous linings and corner block wood, holding the steel absolutely square with the rib, or you will be all abroad. It is this squareness that is the severe test and your great trouble just now. Try on anything and on everything before you try it on a rib you may spoil; but do it on something or other, and finally you will do it and well on these ribs.
But, after cutting, you will have still more to do—lay them flat and keep them so and rigid with left hand whilst you, with rasp [47], fine side, level from one end to the other, not from you across the rib, as the other way is safer for keeping square, and obviates the risk of tearing away part of a lining or slip from a corner block.
You will have dressed the ribs at the outset as instructed; but you will now find them anything but fit to attach to the back; so trim and make them free from any blemish or stain of dirt, and then do your best to fit one side accurately, so that, when glued afterwards, there may be no discrepancies nor goings back.