The Technique of FURNITURE MAKING

MARKING, MEASURING AND TESTING TOOLS

Traditionally the furniture-maker has relied upon the standard 2 ft (609 mm) fourfold rule, the joiner on the 3 ft (914 mm) pattern, both

marked in eighths and sixteenths of an inch, and obtainable as standard or blindman's, the latter with extra bold figurings. For long lengths the standard boxwood rule or the engineer's long one-piece rule are preferable to flexible steel tapes which should not be used for highly critical work on the bench. Finely divided semi - flexible engineers' steel rules are very useful, also the stout square-end type not finely divided which can be used as either rule or short straight-edge, for if the edge of the rule is rubbed over the wood it will immediately high­light ridges and raised spots which are not discernible to the naked eye with a black metal shine. A useful accessory is the Stanley com­bination try-mitre-square and depth-gauge incorporating a sliding-rule (Figure 43:1), while the vernier caliper gauge (43:2) is invaluable for measuring exact thicknesses. These can be obtained as engineer's precision pattern, or as a more robust pattern specially designed for

12

43 Marking, measuring and testing tools (1)

woodworking. All rules should be used with the markings actually touching the work (Figure 42).

Straight-edges are essential in any workshop and should be plentiful (43:11); they are usually made out of 1/2 in (12.5 mm) by 2 1/2 in
(63.5 mm) mild Honduras mahogany, pine or redwood, waxed or varnished, and in a range of lengths up to 6 ft (1524 mm); while at least one metal straight-edge 4 ft (1.21 m) long or more should be provided for cutting veneers, etc.

Also necessary are winding-sticks (43:4) in matched pairs, usually about 2 ft (609 mm) long by 2 in (50 mm) wide by 1/2 in (12.5 mm) thick of good mahogany or similar wood planed truly parallel, the edges bevelled as shown and small sighting insets of white wood (43:4 A) inlaid into the rear stick. Stub dowels and sockets are also provided so that the sticks can be kept together and hung from a nail, as any deviation from the straight, or uneven shrinkage across the width of either, will result in false readings. If these sticks are placed at either end of a planed-up board and sighted through from a few feet away the white wood insets will immediately confirm any slight tilt, disclosing that the board is twisted, i. e. both edges may be straight but the diagonal is curved, giving a twist or wind to the wood. Squaring-rods (43:12) of about 1 in (25 mm) by 5/16 in (8 mm) straight-grained wood in various lengths and blocked and point­ed at one end are used for checking the square­ness of carcass openings, etc., for it is never safe to rely upon the try-square alone over a large area (see Carcass construction, Chapter 21).

Note: Introduction of the metric system will

eventually necessitate changing the sizes of all standard tools now conforming to inch measurements. As this is likely to be a lengthy process, and as the conventional sizes to be adopted have not yet been established, all the tools mentioned in this and subsequent chapters are inch patterns with the approximate metric equivalents given in parentheses.