GB890022A - Improvements in or relating to jigs primarily for use by wood workers - Google Patents

Abstract

890,022. Dovetailing. ROBINSON & CO. Ltd., A., and WAITE, J. L. Sept. 1, 1958 [July 9, 1958], No. 21944/58. Class 145. A jig for producing dovetail joints with the aid of a portable manual or power-driven tool comprises a pair of workpiece supports 10, 11 at right angles to each other and a guide member having at least one slot 17c, 33 or 55 for receiving a sleeve 22 in which a tool holder 23 is journalled, the sleeve having a pair of slots 22a which engage front and rear guide surfaces at the edges of the slots in the guide member. The support 10 is vertically adjustable on the support 11 and the two supports are clamped together by wing nuts 15, the adjusted position being indicated by a scale 10d, Fig. 1. Studs 18 and wing nuts 19 secure the guide member 17 to the support 11 and two different transverse locations are provided by a pin 21a engaging in one of two holes 21 in the support 11. The centres of the holes 21 are at half the pitch of the slots 17c in the member 17 and work locating studs 12 and 31 on the supports 10 and 11 are spaced apart a lateral distance equal to the spacing of the holes 21. The workpiece B is thus offset from the workpiece A and by passing the sleeve 22 with the rotating tool 25 down the series of slots 17c in turn and then repeating the operation with the pin 21a located in the other hole 21 complementary dovetail tongues and grooves can be cut in the two workpieces. The work supports may be provided with holes through which G-clamps can be passed, as shown in Fig. 1, or spring-loaded clamping bars 42, Fig. 10, on screw studs 43 may be provided. The guide member 17 may abut fixed lugs 11b on the support 11 or may have horizontal adjustment provided by a slotted member 34, Fig. 10, a spacing bar 41 being clamped between abutments 34a and the face of the workpiece A to ensure that workpieces of varying thickness can be cut to the same extent by the tool 25. As shown in Fig. 16, the guide member 54 has a single guiding slot 55 and is slidable along a bar 57 which can be mounted on the studs and four sets of teeth at different pitches. By turning the bar upside down or end for end, a particular set of teeth can be selected and a projection 64 on the member is engaged in turn between the teeth of that set. For disengaging the projection from a tooth, a cam 67 is turned until a flat 67a is uppermost and a plate spring 69 then raises the projection. For cutting a single dovetail tongue and a corresponding groove in two workpieces, as in the construction of shelving, the guide member 32 of Fig. 11 is secured on the studs 18. A groove can be cut across a workpiece on the support 11 by traversing the sleeve 22 along the slot 33 and a corresponding tongue can be formed on a workpiece on the support 10 by two passes at different heights, the height adjustment being obtained by moving the support 10 vertically or by providing vertical adjustment for the member 32. The open end of the slot 33 may be closed by a screwed stud and a distance piece or by an E-shaped clip 53.