I thas been found difficult, when performing drilling or cutting threads, exactly to locate in its described position the hole to be drilled in a workpiece. It is especially troublesome when the hole to be drilled or threaded is located in a corner or when it is inclined by 45°C. The same problem arises when the workpiece has concave or convex surfaces.

The object of the present invention is to provide a device for guiding a drilling or thread-cutting operation at which the above mentioned problems have been eliminated. The features characterizng the invention are set out in the claims.

Accordingly, the drilling and thread-cutting device of the invention facilitates the work when the hole to be drilled must be oriented with an inclination angle of exactly 90° or 45 relatively a flat surface or when it is located at a corner of different types of workpieces. Furhter, the device can be provided with different kinds of adapters when the drilling is carried out through e. g. concave or convex surfaces. When the drilling operation is performed in wood, it is also possible to use an adapter particularly designed for that purpose. The drilling and thread-cutting guide device has a guide unit that can be inserted into different guide sleeves the inner dia- meters of which are matching the outer diameter of the tool used, whereby one does obtain an exact positioning of a drill or screw tap used to machine the workpiece.

As soon as the guide sleeve to be used has been placed in position in the guide unit of the drilling and thread-cutting device, the drill can be moved through the sleeve into contact with the workpiece making it possible to perform a very exact and straight working operation.

Once the guide unit has been put in place on the workpiece selection of other guide sleeves can be made. By way of example, a drill sleeve can be replaced by a thread-cutting sleeve etc, resulting in an exact working operation, since there is no need to move the guide unit in order to change the sleeve. Consequently, the end result is that the hole and the threads will be completely coaxial.

Some embodiments of the invention will now be described with reference to the drawing.

Fig. 1 is a lateral view of a drilling and threading guide unit according to the invention, equipped with a guide sleeve for a drill tool.

Fig. 2 is a top view of the unit shown in fig. 1 but without sleeve and drill.

Fig. 3 is a bottom view of a guide unit according to fig. 1 and provided with a magnet.

Fig. 4 is a lateral view of the unit in fig. 1, its guide sleeve being in a partially entered position.

Fig. 5 is a lateral view showing four guide sleeves with mutually different diameters.

Fig. 6 illustrates an alternative ambodiment of the device according to the invention, the support portion for the guide unit being adapted for a drilling operation at an angle of 45° relatively the workpiece.

Fig. 7 is a bottom view of the drilling and thread-cutting guide unit shown in fig. 6.

Fig. 8 is a top view of the device shown in fig. 6.

Fig. 9 is a lateral view showing a stage where the guide unit has just been taken away from the workpiece.

Fig. 10 shows another alternative embodiment of the device according to the invention the support portion being designed for drilling in a corner of a workpiece.

Fig. 11 illustrates the device shown in fig. 10 mounted in position on a workpiece, the guide sleeve being pushed into the guide unit.

Fig. 12 is a bottom view of the device shown in fig. 8 och 9.

Fig. 13 illustrates an adapter intended to be fixed in position in contact with the bottom surface of the device shown in fig. 1 and to be used in connection with the drilling of holes in a wooden workpiece.

Fig. 14 is a top view of the adapter shown in fig. 13.

Fig. 15 is a diagrammatic, lateral view of an adapter to be used for wooden workpieces and provided with an extension permitting it to be fixed in position with the end of a clump, not shown in the drawing.

Fig. 16 is a top view of the adapter shown in fig. 15.

Fig. 17 is a cross-sectional lateral view showing a drilling and threading guide combined with an adapter for convex surfaces.

Fig. 18 is a lateral view of an adapter for co-operation with a device according to fig. 1 and designed to be used on convex surfaces having a smaller diameter than that shown in fig. 17.

Fig. 19 is a bottom view of the device shown in fig. 17.

As appears from the drawing, especially from its figs. 1-5, there has been shown a preferred embodiment of the invention in the shape of a drilling and thread-cutting guide device 1 comprising a guide unit 3 which can be fixed in position on a workpiece 2 and exhibits a support portion 5 at its lower part 4. The guide unit 3 cooperates with a guide sleeve 6, which can be inserted into the unit and the inner diameter of which matches the machining tool, that is to be used e. g. a drill 7.

The support portion 5 is constituted by a mounting piece 8 which can be mounted on the workpiece 2 and does both support the guide unit 3 and hold it in position. In this way a working operation can be carried out in exactly the predetermined position on the workpiece 2.

The mounting piece 8, constituting the support portion 5, has at least one magnet 9, which is countersunk in its bottom surface 10 and, thanks to the shape of mounting piece 8, holds the drilling and thread-cutting guide fixed in position on the workpiece 2 which in this example consists of metal.

In order to facilitate the release of the drilling and thread- cutting guide from the workpiece 2 mounting piece 8, constituting the support portion 5, comprises means 22 for lifting the drilling and thread-cutting guide. Those means 22 are constituted by a pin 21 located at and extending through the circumpherential portion of mounting piece 8 and which, by means of a lever having an oval pressure section, can be displaced towards and into contact with the workpiece. The support 5 of the drilling and thread-cutting guide does also include a ring-shaped magnet 9 countersunk in its bottom surface 10.

In the embodiment shown in figs. 6-9 the support portion 5 consists of two support plates 14,15, oriented at an angle between them and comprising inclined contact surfaces which are to contact the workpiece 2'. The magnet is here in the shape of elongated rods 16,17 countersunk in the bottom 10'of mounting piece 8.

In the embodiment shown in figs. 10-12 the mounting piece 8 consists of three support plates 18-20 with contact surfaces mounted at angles to match the angles of a workpiece 2''. Each support plate 18-20 has its own magnet 23.

In figs. 13-16 there is shown an adapter 11 for fixation of the drilling and thread-cutting guide on a wooden workpiece. The adapter 11 consists of a support plate 24 which exhibits either pins 25 which can be pushed into the wood surface, or an extension 26 by means of which the adapter, and its mounted drilling and thread-cutting guide 1 can be fixed in position.

The adapter 11 has a metal ring 28 countersunk in a recess 27 for cooperation with that or those magnets which are located in the mounting piece 8 of the drilling and thread-cutting guide 1 (see fig. 1). In those cases when the adapter 11 is made in a metallic material, this ring can be omitted.

When the drilling and thread-cutting guide is to be used for drilling and/or thread-cutting in convex surfaces use is made of an adapter 12, shown more in detail in figs. 17-19. In fig.

17 the adapter 12 has a somewhat greater diameter than that of the adapter 13 shown in fig. 18. The adapters 12,13 have knob means 29 intended to cooperate with corresponding recesses 30 in the mounting piece 8 of the drilling and thread-cutting guide 1. When concave surfaces are to be machined use is made of an adapter having a convex shape.