Apparatus for mounting and pivoting a device on a base

Abstract: An apparatus for mounting a device, such as a saw blade, on a base (3) to enable the blade to be positioned accurately in either of two distinct positions relative to the base. The apparatus comprises a pivot member (21) for supporting the blade (not shown) pivotally mounted on a fixed member (11). The fixed member (11) includes a pair of abutments (142,144) and the pivot member has at least one asymmetric stop (160) for abutting the abutments (142,144) after rotation of the pivot member (21) relative to the fixed member to define the distinct positions of the blade. These positions are defined generally by the positions of the abutments (142,144) and accurately by the orientation of the or each asymmetric stop (160). The apparatus may further include a device (170) for adjusting accurately one of the distinct positions by a predetermined amount.

Description: This invention relates to apparatus for mounting a device on a base to enable the device to be positioned accurately in either of two distinct positions relative to the base. The invention is particularly applicable to a bevel saw or the like, wherein a saw blade must be accurately positioned relative to a surface supporting a workpiece during cutting of the workpiece. In a bevel saw, the blade is either vertical or at some angle to the vertical, usually up to 45°. It is moved in the plane of the blade to cut a workpiece oriented on a horizontal table. There are two normal positions: that is to say, the vertical position for cutting right-angle cuts in the workpiece and 45° for making mitre cuts for joining two similarly cut pieces at right angles. With such normal cuts it is desirable to arrange two limit stops, so that the saw can quickly and easily be adjusted to either position. Hitherto these have consisted simply of bolts or the like screwed into housings which bolts can be adjusted to accommodate any manufacturing tolerances in the saw parts. It is an object of the present invention to provide an apparatus which improves upon existing arrangements. With the foregoing in mind, the present invention provides an apparatus for mounting a device on a base to enable the device to be positioned accurately in either of two distinct positions relative to the base, the apparatus comprising a pivot member for supporting the device pivotally mounted on a fixed member of the base, the pivot member and the fixed member including a pair of abutments and at least one asymmetric stop for abutting the abutments after rotation of the pivot member relative to the fixed member to define the distinct positions of the device, wherein the two distinct positions are defined generally by the positions of the abutments and accurately by the orientation of the or each asymmetric stop. Hence, if the device is a circular saw or the like and the base is a base table upon which a workpiece is to be positioned, two cuts at exactly 45° (for example) to each other can be readily achieved. Preferably the abutments are defined by end walls of a segmental channel, which extends around the pivot axis of the apparatus. The segmental channel may be formed on the fixed member and the or each asymmetric stop is then mounted on the pivot member. Alternative arrangements can, of course, also be envisaged. The or each asymmetric stop may comprise a shaft and an eccentric head at one end thereof. Preferably the shaft of each asymmetric stop passes through the pivot member (or the fixed member) so that the orientation of the eccentric head can be adjusted from the side of the pivot member opposite to the head simply by rotating the shaft. Each asymmetric stop is preferably fixed to the pivot member (or the fixed member) by a locking nut on the end of the stop distal from the eccentric head. Preferably two asymmetric stops are provided, one abutting one abutment in a first of the two distinct positions and the other abutting the other abutment in the second of the two distinct positions. By including two asymmetric stops, further flexibility is provided in adjusting the positions of the two distinct positions. In one embodiment of the present invention, the distinct positions are separated by an angle of approximately 45° about the pivot axis. Clearly any other desired angle could be achieved, simply by changing the relative positions of the abutments. In any event, a saw incorporating this, or indeed any prior art arrangement is normally limited to movements between zero and 45°. If greater angles are required then the workpiece must be turned over and cut from the other direction so that the saw is then limited between 45° and a right-angle. However, it may not always be possible or easy to turn the workpiece around. Moreover, it is likely that the desired cut may be only a little more than 45°, as is typically the case when mitring workpieces to form joints to fit in older houses, where walls, floors and ceilings never seem exactly to meet at right angles. Thus it is a further object of the present invention to provide apparatus which overcomes this problem, or which at least mitigates its effects. According to another aspect of the present invention, there is provided an apparatus for mounting a device on a base to enable the device to be positioned accurately in either of two distinct positions relative to the base, the apparatus comprising a pivot member for supporting the device pivotally mounted on a fixed member of the base, an abutment on one of the pivot member or the fixed member and a camming device on the other of the pivot member or the fixed member for abutting the abutment to define the relative positions of the pivot member and the fixed member about the pivot axis, wherein the camming device includes two surfaces which, when brought into contact with the abutment, accurately define two predetermined distinct positions of the pivot member relative to the fixed member. Preferably the camming device includes means for holding the chosen surface in contact with the abutment. The holding means may comprise a pimple on the camming device for engaging a dimple in the pivot member or fixed member, as appropriate. Other holding means can, of course, also be envisaged. The two positions of the pivot member are preferably separated by an angle of approximately 3° about the pivot axis. This angle depends on the relative positions of the two surfaces of the camming device, and can be adjusted by altering the camming device accordingly. As will be appreciated, if the camming device includes more than two working surfaces, additional distinct positions of the pivot member relative to the fixed member may be provided. Preferably the camming device is mounted on the pivot member and the abutment is formed on the fixed member. The camming device may include a knob extending through a window of the pivot member to facilitate changing of the surface in contact with the abutment. The camming device is preferably mounted on a stub such that the camming device pivots about the stub axis to change the surface in contact with the abutment. In a particularly preferred embodiment of the present invention, the stub is the eccentric head of an asymmetric stop of an apparatus as herein described. Although the present invention is particularly applicable to an apparatus for mounting a circular saw on a base table to provide accurate cutting of a workpiece on the table by the saw, the invention may be applied to any other appropriate situation. The present invention is now described, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a front view of the pivot member of an apparatus according to the present invention; Figure 2 is a side view of the pivot member connected to the back of a round table of a saw, which is in section along the line II-II in Figure 3; Figure 3 is a back view of the round table showing its pivot block; Figure 4 is a section along the line IV-IV in Figure 1; Figure 5 is a more detailed, cut-away view of Figure 2; Figure 6 is a super-imposed view of the pivot member on the pivot block, from the rear; Figures 7a, b and c are an end view, a sectional side view and a view of the other end of a cam stop sleeve of the saw; and Figures 8a and b are end and side views of eccentric bevel stops. With reference to the drawings, a pivot member 21 for receiving a circular saw (not shown) is connected to a pivot block 11 of a round table 3 for relative rotation about axis 70/71. The pivot member 21 has an annular surface 73 for flush engagement with a similar face 72 on the pivot block 11. In the body of the pivot block 11 is formed a segmental part-annular channel 140, which has two end walls 142,144. In the same mating region of the pivot member 21, in a similar segmental part-annular channel 146 in its body, are formed two bosses 148, 150. The bosses 148,150 each have a central bore 152,154 respectively, each adapted to receive, in a close fit, a shaft 156 of a bevel stop 160 (see Figures 5 and 8). The shaft 156 has an eccentric cylindrical head 158 at one end and is threaded at its other end 162. The threaded end 162 has a hexagonal socket 164 formed therein. The head 158 has a bearing surface 166 formed thereon. With reference to Figure 5, a bevel stop 160 is fitted in each bore 152,154 from the front of the pivot member 21 before the pivot member 21 is mated with the pivot block 11. A nut (not shown) is screwed on the end 162 to lock the stop 160 in place. When the pivot block 11 and pivot member 21 are mated, the heads 158 of the stops 160 project into the channel 140 of the pivot block 11. The boss 150 and the wall 142 of the channel 140 are so arranged that when a stop 160a (see Figure 6) is received in the bore 154, the bearing surface 166 of the head 158 abuts the wall 142 when the pivot member 21 is vertical with respect to the pivot block 11 on the round table 3, assuming, of course, that the latter is horizontal. To allow for manufacturing tolerances, the verticality of the saw blade (not shown) needs to be adjustable and this is provided by the eccentricity of the head 158. A key inserted in hexagonal socket 164 enables the shaft 156 to be rotated, once the nut (not shown) is slackened from the threaded end 162. Rotation of the shaft 158 changes the disposition of the bearing surface 166 of the stop 160a relative to the end wall 142 so that precise verticality of the blade can be assured. The other stop 160b is essentially the same construction as stop 160a except that, before it is inserted in the bore 152 of the pivot member 21, a cam stop sleeve 170 may be slipped over the head 158 and bearing surface 166. The cam sleeve 170 has a bore 172 having diameters corresponding with the head 158 and surface 166 so that it is a close fit on the stop 160b. The pivot member 21 has an arcuate window 178 which is centred on the bore 152. A knob 174 of the cam stop sleeve 170 is arranged to project through the window 178 when the sleeve is located on the bevel stop 160b such that the knob 174 is actuable from behind the pivot member 21. A pimple 176 formed on the cam stop sleeve 170 is adapted to co- operate with one of two dimples 180in the face of the pivot member 21 on the boss 148. The cam stop sleeve 170 has two flat surfaces 182, 184 opposite the knob 174. Referring to Figure 6, the bevel stop 160b is in the position shown when the pivot member 21 is supporting the saw blade vertically relative to the table 3. When it is desired to cut bevels in a workpiece positioned on the table 3, the pivot member 21 and hence the saw blade is pivoted (clockwise in Figure 6) up to 45° relative to the pivot block 11. This brings the stop 160b to the position shown at A in Figure 6. Here one of the surfaces 182,184 of the cam sleeve 170 abuts the end wall 144 of the channel 140. The surfaces 182,184 are arranged so that there is a small angular difference B between them, in terms of the extent to which the pivot member 21 is allowed to pivot with respect to the pivot block 11. Which surface 182,184 engages the wall 144 depends on the position of knob 174 of the cam sleeve 170. As mentioned above, the cam sleeve 170 has two positions, which in Figure 6 are labelled 45° and 48°. In the 45° position, the surface 184 is positioned so that it contacts the wall 144. The boss 148 (and its bore 152) and the wall 144 are so arranged that in this position the pivot member 21 is about 45° to the table 3. However, to allow for manufacturing tolerances, the stop 160b is rotatable in its bore 152 to alter marginally the limit of movement so that 45° can be set precisely for each saw. Having set 45° with some accuracy, it is then possible to rotate the knob 174, springing the pimple 176out of engagement with the first dimple 180 (i.e. that one in the 45° position), to the second position (48°) where the pimple 176 snaps into engagement with the second dimple 180 in that position. In this position it is the surface 182 of the cam sleeve 170 which abuts the end wall 144 and, because this surface 182 is closer to the axis of the bore 152, an extra three degrees precisely of bevel pivot is provided. It will of course be understood that the present invention has been described above purely by way of example, and that modifications of detail can be made within the scope of the invention as defined by the appendant claims.

Claims: An apparatus for mounting a device on a base (3) to enable the device to be positioned accurately in either of two distinct positions relative to the base (3), the apparatus being characterised by a pivot member (21) for supporting the device pivotally mounted on a fixed member (11) of the base (3), the pivot member (21) and the fixed member (11) including a pair of abutments (142,144) and at least one asymmetric stop (160) for abutting the abutments (142,144) after rotation of the pivot member (21) relative to the fixed member (11) to define the distinct positions of the device, wherein the two distinct positions are defined generally by the positions of the abutments (142,144) and accurately by the orientation of the or each asymmetric stop (160). An apparatus according to Claim 1, characterised in that the abutments (142,144) are defined by end walls of a segmental channel (140) which extends around the pivot axis (70,71) of the apparatus. An apparatus according to Claim 2, characterised in that the segmental channel (140) is formed in the fixed member (11) and the or each asymmetric stop (160) is mounted on the pivot member (21). An apparatus according to any preceding claim, characterised in that the or each asymmetric stop (160) comprises a shaft (156) and an eccentric head (158) at one end thereof. An apparatus according to Claim 4, characterised in that the asymmetric stop (160) passes through the pivot member (21) so that the orientation of the eccentric head (158) can be adjusted from the side of the pivot member (21) opposite to the head (158) simply by rotation of the shaft (156). An apparatus according to Claim 4 or Claim 5, characterised in that the or each asymmetric stop (160) is fixed to the pivot member (21) by means of a locking nut on the end of the stop (160) distal from the eccentric head (158). An apparatus according to any preceding claim, characterised in that two asymmetric stops (160a,160b) are provided, one (160a) abutting one abutment (142) in a first of the two distinct positions and the other (160b) abutting the other abutment (144) in the second of the two distinct positions. An apparatus according to any preceding claim, characterised in that the distinct positions are separated by an angle of approximately 45° about the pivot axis (70,71). An apparatus for mounting a device on a base (3) to enable the device to be positioned accurately in either of two distinct positions relative to the base (3), the apparatus being characterised by a pivot member (21) for supporting the device pivotally mounted on a fixed member (11) of the base (3), an abutment (144) on one of the pivot member (21) or the fixed member (11) and a camming device (170) on the other of the pivot member (21) or the fixed member (11) for abutting the abutment (144) to define the relative positions of the pivot member (21) and the fixed member (11) about the pivot axis (70,71), wherein the camming device (170) includes two surfaces (182,184) which, when brought into contact with the abutment (144), accurately define two predetermined distinct positions of the pivot member (21) relative to the fixed member (11). An apparatus according to Claim 9, characterised in that the camming device (170) includes means (176) for holding the device (170) in a desired orientation to expose a chosen surface (182,184) to the abutment (144). An apparatus according to Claim 10, characterised in that the holding means comprise a pimple (176) on the camming device (170) for engaging a dimple (180) in the pivot member (21) or fixed member (11), as appropriate. An apparatus according to any one of Claims 9-11, characterised in that the two positions of the pivot member (21) are separated by an angle of approximately 3° about the pivot axis (70,71). An apparatus according to any one of Claims 9-12, characterised in that the camming device (170) is mounted on the pivot member (21) and the abutment (144) is formed on the fixed member (11). An apparatus according to Claim 13, characterised in that the camming device (170) includes a knob (174) extending through a window (178) of the pivot member (21) to facilitate changing of the surface (182,184) exposed to the abutment (144). An apparatus according to any one of Claims 9-14, characterised in that the camming device (170) is mounted on a stub such that the camming device pivots about the stub axis to change the surface (182,184) exposed to the abutment (144). An apparatus according to Claim 15, characterised in that the stub is the eccentric head (158) of an asymmetric stop (160) of an apparatus according to any one of Claims 4 to 6. An apparatus according to any one of Claims 9 to 16 and according to any one of Claims 1 to 8. A saw incorporating an apparatus according to any preceding claim, characterised in that a saw blade is positioned relative to a base table (3) via the apparatus.

Inventors: FOLCI GIOVANNI ANTONIO, FOLCI, GIOVANNI ANTONIO
Applicants: BLACK & DECKER INC, BLACK & DECKER INC.
Application year: 1993
Main classification: B27B5
IPC codes: B23D45, B23D47, B27B5