GB2138742A

GB2138742A - A circular saw

Info

Publication number: GB2138742A
Application number: GB08411047A
Authority: GB
Inventors: Karl-Heinz Hoffman; Dietrich Marx; Helmut Ulm
Original assignee: Black and Decker Inc
Current assignee: Black and Decker Inc
Priority date: 1983-04-29
Filing date: 1984-04-30
Publication date: 1984-10-31
Also published as: GB2138742B; FR2547763A1; DE8312668U1; FR2547763B1; GB8411047D0

Abstract

A circular saw has a gap wedge 22 to project from the saw casing 10 parallel with the saw blade 20. An adjusting member 26 is so arranged relative to the casing 10 and the gap wedge 22 as to be operable to adjust the position of the gap wedge 22 such that, in use, it is aligned to follow in the incision made by the saw blade 20 in the workpiece. A bearing surface 25 is inclined relative to the plane of the saw blade 20 so as to require the adjusting member 26 to bear on the gap wedge 22 to align the same. <IMAGE>

Description

SPECIFICATION A circular saw This invention relates to a circular saw.

A known circular saw comprises a casing adapted to receive a saw blade, said saw blade (when present) being mounted for rotation about an axis of rotation and projecting from the casing for engagement with a workpiece, a gap wedge intended to project in use from the casing in substantially the same direction and substantially the same plane as the saw blade.

Such circular saws exist in various constructions. The purpose of the gap wedge is to enter the gap resulting from an incision in a workpiece in order to prevent the gap from closing behind the saw blade and thereby jamming the saw blade.

Prior art gap wedges are made of hardened steel plate. They are so attached to the saw casing during the assembly of the circular saw that they lie in the same plane as the saw blade. Lying in this plane they may enter the gap produced in the workpiece by the saw blade. However, after attachment to the casing, the gap wedge may not lie precisely in the plane of the saw blade. It has been found that, for similar machines the deviations in the alignment of the gap wedge usually occur in the same direction. Thus, after mounting, the gap wedge must then be bent manually into alignment with the saw blade, thus substantially increasing manufacturing costs.

The user of the circular saw may also accidentally bend the gap wedge to one side. In this event the user must also attempt to remedy this mis-alignment by bending the gap wedge back. Such bending of the gap wedge, especially one made of hardened steel plate, is difficult and frequently leads to the kinking of the gap wedge.

The present invention seeks to provide an improved circular saw in which the gap wedge may be very simply aligned to lie in the plane of the saw blade.

According to the present invention there is provided a circular saw comprising a casing adapted to receive a saw blade, said saw blade (when present) being mounted for rotation about an axis of rotation and projecting from the casing for engagement with a workpiece, a gap wedge intended to project in use from the casing in substantially the same direction and substantially the same plane as the saw blade, wherein there is provided an adjusting member so arranged with respect to the casing and the gap wedge as to be operable to adjust the position of the gap wedge such that, in use, said gap wedge is aligned to follow in the incision made by the saw blade in the workpiece.

In an embodiment of the circular saw according to the invention, therefore, an adjusting member is provided by means of which the position of the gap wedge may be altered in a very simple manner. The gap wedge may be "bent" by means of the adjusting member and brought into the plane of the saw blade.

In order to ensure that, irrespective of the post assembly attitude of the gap wedge, the adjusting member is operable to adjust the alignment of the gap wedge, provision is made for a bearing surface for securing the gap wedge against the casing, said bearing surface being inclined relative to the plane of the saw blade so as to require said adjusting member to bear on the gap wedge to align same. The gap wedge may then be displaced into the plane of the saw blade by displacing the adjusting member in the required manner.

In an embodiment the adjusting member comprises an adjusting screw which extends parallel with the axis of rotation and whose free end is movable into engagement with the gap wedge in a zone lying between said bearing surface and the free end of the gap wedge.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a plan view of a portable, electrically driven circular saw whose casing is partly opened up to show the attachment of the gap wedge and the adjusting member, and Figure 2 shows a side elevation of the circular saw illustrated in Figure 1, showing the position of the adjusting member in the casing and the attachment points for the gap wedge.

The circular saw illustrated has a casing 10 which encloses the upper portion of a saw blade 20 (shown in chain lines in Figure 2) and has a motor casing part 11 for receiving an electric motor and a handle casing part 12. The casing 10, including the parts 11 and 12, may be made up of parts moulded from plastics material.

A connecting lead 1 3 extends from the handle casing part 12 and is provided with a plug, via which the power supply is connected to the electric motor. A saw shoe 1 5 is attached to the casing 10. In use, the saw shoe 1 5 of the circular saw bears against the workpiece. This saw shoe 1 5 may be turned relative to the saw blade 20 by releasing an adjusting head 1 4 whereby it is possible to effect and adjustment for mitring. A stop 17, which is disposed adjustably on the saw shoe 15, may be locked by means of a clamping device 1 8.

The saw blade 20 is mounted on a shaft (not shown) whose longitudinal axis 21 (the axis of rotation) is indicated in Figure 2. As viewed in Figure 2, the saw blade 20 extends downwardly beyond the saw shoe 1 5. The depending portion of saw blade 20, when the blade is inoperative, is covered by a pendulum hood 16 which is biased into the position illustrated in Figure 2, for 'example, by the force of a spring (not shown). The pendulum hood 1 6 is slotted in the plane of the saw blade and comprises two halves, each of which covers an area of the saw blade. The pendulum hood 1 6 is displaced by the engagement of its lug 1 6' with a workpiece and the corresponding advancing movement of the circular saw, whereby the rotating saw blade 20 is released and cuts into the workpiece.

A gap wedge 22 is attached to wall 25 (Figure 1) of the casing 10 by means of two screws 23 and check or locking nuts 24. Gap wedge 22 is situated relative to the direction of advance of the saw, behind the saw blade 20. The gap wedge 22 extends in the same manner as the saw blade 20 downwardly through the saw shoe 1 5 (Figure 2).

In operation, the gap wedge 22 must lie precisely in the plane of the saw blade 20, to be able to enter the incision produced thereby in the workpiece.

When the gap wedge 22 is mounted on the casing by means of the screws 23, it bears via its immediate attachment zone against the wall 25.

However, its portion lying below the attachment zone and below the wall 25 may so extend that the wedge 22 is not precisely in the plane of the saw blade. To compensate for this deviation of the gap wedge 22 from its correct position, an adjusting member 26 is provided in the casing 10.

The adjusting member in this embodiment takes the form of screw 26, which is disposed beneath the attachment zone formed by the screws 23 and beneath the portion of wall 25 forming the bearing for the gap wedge 22. Adjusting screw 26 therefore lies nearer to the free end of the gap wedge 22 than the two screws 23 (Figure 2).

When therefore adjusting screw 26 is displaced relative to nut 27 in the direction of the gap wedge 22, inserted non-rotatably, its free end comes into engagement with the gap wedge 22.

The nut 27 is non-rotatably mounted in the casing 10 and retained by means of a cover plate 28.

When the adjusting member 26 is so displaced it forces the gap wedge 22 downwards, as viewed in Figure 1, so that the wedge arrives in the plane of the saw blade 20. In order to ensure that the adjusting member 26 enables the gap wedge 22 to be aligned in any case, an inclined bearing surface is provided for the gap wedge. This bearing surface, which is formed by the wall 25, is downwardly inclined (although not shown in Figure 1) so that the top end of the gap wedge 22 (as viewed in Figure 2) is somewhat further from the opposite casing wall. It is the opposite casing wall through which the adjusting screw 26 extends. In contrast the gap wedge in a zone in the area of the bottom screw 23 is nearer to said opposite casing wall. This is due to the inclination of the bearing surface in the direction of the adjusting member 26. In consequence the gap wedge 22, when mounted, is inclined relative to the plane of the saw blade 20. The inclination of the bearing surface is so selected that the gap wedge 22 is inclined out of the plane of the saw plate 20 over the whole range of tolerance. If necessary the extent of inclination may be to a varying extent.

During final assembly of the circular saw, the inclination of the gap wedge 22 is eliminated by correspondingly displacing the adjusting member 26 causing the gap wedge 22 to be forced by means of the adjusting member 26 into the plane of the saw blade 20.

Claims

1. A circular saw comprising a casing adapted to receive a saw blade, said saw blade (when present) being mounted for rotation about an axis of rotation and projecting from the casing for engagement with a workpiece, a gap wedge intended to project in use from the casing in substantially the same direction and substantially the same plane as the saw blade, wherein there is provided an adjusting member so arranged with respect to the casing and the gap wedge as to be operable to adjust the position of the gap wedge such that, in use, said gap wedge is aligned to follow in the incision made by the saw blade in the workpiece.

2. A circular saw as claimed in Claim 1, wherein the casing is provided with a bearing surface for securing the gap wedge against the casing, said bearing surface being inclined relative to the plane of the saw blade so as to require said adjusting member to bear on the gap wedge to align same.

3. A circular saw as claimed in Claim 2, wherein the adjusting member comprises an adjusting screw which extends parallel with the axis of rotation and whose free end is movable into engagement with the gap wedge in a zone lying between said bearing surface and the free end of the gap wedge.

4. A circular saw arranged, constructed and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.

5. A circular saw having a saw blade which can rotate around an axis of rotation and which is mounted in a casing from which it partially projects for engagement with a workpiece; and a gap wedge which is attached to the casing, projects from the saw blade in the same direction as the saw blade, and lies in the same plane as the saw blade, characterised by an adjusting screw which is provided in the casing and which extends parallel with the axis of rotation and whose free end can be moved into engagement with the gap wedge in a zone lying between the bearing surface of the gap wedge against the casing and the free end of the gap wedge.

6. A circular saw according to Claim 5, characterized in that in the absence of engagement with the adjusting screw, the gap wedge is bent out of the plane of the saw blade in the direction of the adjusting screw.