The Handyman's Book of Tools, Materials, and Processes Employed in Woodworking. Paul N. Hasluck
Fig. 423.—Wrong Method of Forming Burr Edge.
Fig. 424.—Using Badly Sharpened Scraper.
GLASSPAPER.
Glasspaper is the chief abrading material used in woodworking, and consists of strong paper coated with powdered glass. In the manufacture of glasspaper, first the glass is washed and sorted, and then broken very fine by stamps or other machinery. The glass chiefly used for best glasspaper is that from old port wine and stout bottles; this, when pulverised, is of a golden colour. The different grades of glasspaper are numbered from 3 to 0 (and even finer), and there are corresponding sieves to divide the various grades, or to “size,” as it is technically called. These sieves are numbered from 140 to 30, the numbers representing the number of meshes per lineal inch; the finer sieves are covered with Swiss silk, the remainder with woven wire. In this part of the process considerable care must be exercised, as one large particle of glass on a sheet of fine paper would scratch the work upon which it was used, and would produce an uneven surface. The placing of the glass on paper requires considerable skill and experience. The workman has delivered to him plain paper in reams of 120 sheets, each sheet making four sheets of ordinary size. The appliances used are a copper holding 56 lb. of glue, a table, a bench on which the sheets are laid to cover them with glass, a hot plate for firing the sheets, a drying room, a cutting machine, and a press for packing and tying up. A ream or two of paper is placed on the table, and the top sheet is coated with glue by means of a brush resembling a boot-brush, but with longer hair. The sheet is lifted by two corners and laid on the bench, glue side uppermost; the bench has a border standing up some 7 in. or 8 in. high on three sides, with a narrow fillet in front. Powdered glass is simply thrown or scraped over the sheet, which then is raised from one side so that the superfluous glass runs off on to the bench and is used again. The sheet is then placed on the hot plate, a hollow, flat iron bench heated with steam; this causes the glue to boil up and thus securely fix the particles of glass on the paper. All this is done much more quickly than it can be described. After drying, the sheets are cut up and arranged in quires and reams ready for the market. Glasspaper has entirely replaced the old-fashioned sandpaper; this was made in the same way as glasspaper except that sharp, fine sand instead of glass was used.
Fig. 425.—Wrong Method of Forming Burr Edge.
Figs. 426 and 427.—Badly Sharpened Scrapers.
Fig. 428.—Special Steel Scraper.
Fig. 429.—Special Steel Scraper.
HOW TO USE GLASSPAPER.
For properly using glasspaper a rubber is needed. A piece of mahogany or clean pine, 5 3/4 in. by 3 in. by 1 in., shaped as in Fig. 430, answers well if a piece of sheet cork is glued on the face as shown. Fold a piece of glasspaper, 6 in. wide and about 10 in. long, into three, place it glass side downwards, and put the face of the rubber on the middle division. Grasp the rubber so that the ends of the glasspaper are held firmly on its back and sides (see Fig. 431), and work then can be commenced.
RASPS.
The woodworker occasionally uses rasps, and these generally are half-round, though sometimes flat. The wood rasp (Fig. 432) is coarser than the cabinet rasp (Fig. 433). Cabinet and wood rasps range from 4 in. to 14 in. in length, and at 12 in. and less the price is about 1d. per inch. The extra 2 in. in a 14-in. rasp adds nearly 50 per cent. to the price. Files also are used, but principally for keeping saws in order, and those necessary are mentioned on p. 73.
Fig. 430.—Glasspaper Rubber.
Fig. 431.—Using Glasspaper Rubber.
THE USE OF GRINDSTONES.
When a plane iron, chisel, or other edge tool has been sharpened on the oilstone a number of times, the edge becomes thick. There is too much metal for the oilstone to remove, so the grindstone has to be employed. The grindstone is not a tool for producing a cutting edge, but one for removing a superfluous thickness of metal, yet in nine cases out of ten tools are ground right up to the edge, and often there is 1/16 in, of wire edge to be removed by the oilstone, this being entirely waste. The grindstone should never be allowed to work quite up to the cutting edge of the tool unless it is to remove a gap.
SELECTING GRINDSTONES.
The grindstone, as a rule, is neglected except just when it is wanted for use; consequently, it is only with difficulty that tools can be ground on it at all. A good grindstone kept in proper order will save its own cost in twelve months. It should be selected of a light grey colour, even throughout. A dark streak through the centre, or a dark patch on one place, indicates that the stone is much harder at those places than elsewhere; consequently, it will wear away faster at the softer parts, and will never be truly round for long together. It will-wear lumpy, and at the dark places the tool that is being ground will glide over easily, and directly afterwards catch hold of the softer stone suddenly, and most likely “dig in.” A stone that shows flaws on the sides, such as little smooth places running into it with fine cracks showing away from the ends, should be rejected, as such a stone will not stand frosty weather; a thick stone, also, is undesirable—one 3 1/2-in. or 4 in. wide on the face being ample—as it will tend to wear hollow, and from that cause always be faulty. A smooth stone with a bluish tint should be avoided, as it will work harder and smoother till it becomes like a glass bottle, and of no use at all for proper work. Choose a stone of from 30 in. to 36 in. in diameter and 3 1/2 in. to 4 in. thick, of an even light grey colour, with a rough, gritty surface. Test it with the thumb-nail, and the stone should wear the nail down with a few rubs backwards and forwards and leave straight furrows on the nail; this shows a good free-cutting stone.
Fig. 432.—Half-round Wood Rasp.
Fig. 433.—Half-round Cabinet Rasp.
MOUNTING AND CARE OF GRINDSTONES.
A grindstone mounted in a dwarf iron stand is shown by Fig. 434; this is one of the cheapest forms for the worker’s use, but. of course, one mounted on a high iron or wooden stand with treadle, as in