GB2295987A

GB2295987A - A bevel table saw adjusting mechanism

Info

Publication number: GB2295987A
Application number: GB9425388A
Authority: GB
Inventors: Umberto Sberveglieri
Original assignee: STROMAB Srl; Black and Decker Inc
Current assignee: STROMAB Srl; Black and Decker Inc
Priority date: 1994-12-12
Filing date: 1994-12-12
Publication date: 1996-06-19
Also published as: GB9425388D0

Abstract

A locking device 100, 200 comprising a shaft 42 which, when rotated, achieves a first function, a clamp 104, 204 mounted on the shaft 42 which, when activated, achieves a second function and a knob 102, 202 slidably mounted on the shaft 42 which, in a first position, engages the shaft 42 to enable a user to rotate the shaft 42 and, in a second position, engages the clamp 104, 204 to enable the user to release the clamp. Such a locking device is used with a bevel table saw wherein the depth of cut of a saw blade 64 is adjusted by rotation of the shaft 42 and the angle of cut of the saw blade 64 is determined by movement and subsequent clamping of the rod 42 in arcuate directions. <IMAGE>

Description

A BEVEL TABLE SAW KNOB This invention relates to a locking device arrangement for a bevel table saw wherein the saw blade can be angled to make bevel cuts in a workpiece mounted on the table.

Traversing table saws incorporate a table having a long through-slot for accommodating a saw blade. A drive for the saw blade is accommodated below the table surface so that only a portion of the saw blade is exposed above the table surface. As a result, to cut a workpiece, a workpiece can be either moved past the rotating saw blade or held firmly overlying the slot in the table while the saw blade is drawn along the slot and through the workpiece. Such traversing table saws are well known. Ordinary table saws do not permit traversing and have a correspondingly shorter slot slightly longer than the diameter of the blade.

Bevel table saws, essentially the same as the table saws described above, are also known wherein the angle of the saw blade can be adjusted to allow angled or bevel cuts to be made in a workpiece positioned on the table. Further, it is often desirable to raise or lower the saw blade so that the depth of cut of the saw blade can be varied.

It is known to vary the height of a saw blade by rotating a knob on the end of a rod which activates a worm drive for raising and lowering the saw blade. Further, it is known to lock the rod to a frame of the table saw so that the orientation of the saw blade is kept constant during cutting of a workpiece. This is particularly important when bevel cuts are being made. In the past, however, a separate locking device having a handle has been utilised to lock the rod to the frame.

In view of the foregoing, the present invention aims to improve upon the prior art knob and locking device arrangement by providing a more compact locking device which is simple to use.

According to the present invention, there is provided a bevel table saw comprising a table supported by a frame, and a blade assembly mounted below the table and adapted to carry a saw blade which protrudes through a slot in the table to cut workpieces on the table, the blade assembly being pivotable about an axis parallel the slot to permit bevel cuts in the workpiece, wherein the degree of protrusion of the blade through the slot is adjsutable by rotation of a rod extending from said assembly through an arcuate slot in a front face of said frame, and pivoting of the blade assembly is effected by a user moving said rod along the arcuate slot, and wherein a knob is slidably mounted on the end of the rod and which, in a first position is non-rotatably fixed on the rod and in a second position is engaged with a clamp mounted on the rod and adapted to clamp the rod against pivoting about said axis.

By virtue of the present invention, a separate handle for the clamp is no longer required.

The shaft may carry a shaped end piece which engages a recess in the knob when the knob is in its first position. In a particular embodiment, the end piece is a plate having a plurality of sides which engages a recess in the knob when the knob is in its first position. In a preferred embodiment, the end piece is a plate having a plurality of sides which engages in a recess in the knob which is correspondingly shaped. In such an embodiment, the plate may be substantially hexagonal.

A portion of the knob is preferably shaped to mate with a first part of the clamp such that the first part of the clamp can be rotated relative to a second part of the clamp to release the clamp.

The knob and the first part of the clamp may mate via a plurality of interengaging splines. Any other suitable way of achieving mating between the knob and the first part of the clamp can, of course, alternatively be used.

Rotation of the second part of the clamp may achieve a third function. Hence, the knob may include a second portion which engages the second part of the clamp to enable the second part of the clamp to be rotated after the clamp has been released.

If release of the clamp is achieved by means of splines on the outside of the knob engaging corresponding splines on a first part of the clamp, the splines on the knob may be received in a cavity of the clamp when the knob engages the second part of the clamp. As a result, the splines on the outside of the knob do not engage the first part of the clamp when the knob engages the second part of the clamp.

Interengagement of the splines of the knob and the first part of the clamp may be facilitated by means of an alignment device acting between the knob and the shaft. The alignment device may be a biased ball which engages a recess when the splines of the knob and the first part of the clamp are engaged.

Further, rotation of the second part of the clamp may adjust the bevel angle of the saw blade. More preferably, the second part of the clamp includes a gear or cog which engages a rack on a frame of the saw to define accurately the bevel angle of the saw blade. Further, the frame may include a window through which a bevel angle scale can be viewed, thereby facilitating accurate positioning of the saw blade before cutting.

Specific embodiments of the present invention are now described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of a bevel table saw incorporating a known locking device; Figure 2 is a view in the direction II-II shown in Figure 1; Figure 3A is a side view of a first embodiment of locking device according to the present invention in a first position; Figure 3B is a view of the locking device of Figure 3A in a second position; Figure 4A is a side view of second embodiment of locking device according to the present invention in a first position; Figure 4B is a view of the locking device of Figure 4A in a second position; and Figure 4C is a view of the locking device of Figure 4A in a third position.

With reference to Figures 1 and 2 of the drawings, a bevel table saw 10 comprises a frame 12 having a table 14 in which is formed a long through-slot 16.

At each end of the table 14, at the ends of the slot 16, a half-round bracket 18 is fixed in channels 20 formed in the underside of the table 14 on either side of the slot 16. The brackets 18 each have a half-round track 22 whose centre 23 coincides with the top surface of table 14 and the line of the slot 16.

Engaged with the tracks 22 for sliding, arcuate movement thereon is a saw assembly 30. The saw assembly 30 comprises two parallel bars 32,34 secured between bar supports 33,35 mounted on end frames 36,38. The end frames 36,38 each have a short, arcuate channel section 40 for engagement with the track 22. A rod 42 extends between the two end frames 36,38 and passes through an arcuate slot 44 in the front of the frame 12. The slot 44 is centred on the line of the slot 16. The exposed end of the rod 42 carries a knob 46, as shown in Figure 1. The rod 42 is attached to each end frame 36,38 via a housing 48 which mounts a threaded shaft 50 which carries a spring holder 52 upon which a helical spring 54 is in compression.

A pinion 56 is formed towards the upper end of the threaded shaft 50. The outer surface of the pinion 56 incorporates a gear which engages a worm drive mounted on the rod 42. Rotation of the rod 42 rotates the pinion 56 and shaft 50 and drives the spring holder 52 down the threaded shaft 50. The spring holder 52 is prevented from rotating with the shaft 50 by virtue of a bolt 58 attached to the bar support 33,35.

The bar supports 33,35 carry either end of the bars 32,34 and engage guide rails 62 of the end frames 36,38 such that the bar supports 33,35, and hence the bars 32,34, are moved up and down the guide rails 62 as a result of rotation of the rod 42.

A saw blade 64 driven by a motor 66 mounted on a carriage 68 slidably carried by the bars 32,34 can, therefore, be raised or lowered simply by rotating the rod 42.

To change the angle of cut of the saw blade 64, the end frames 36,38 simply need to be moved along tracks 22. This can be achieved by holding the knob 46 and moving the rod 42 along the slot 44 in the front of the frame 12. When the new position of the saw blade 64 has been reached for angled or bevel cuts, the rod 42 is locked in position by means of a clamp 70. In a prior art embodiment similar to that shown in Figure 1, the clamp 70 comprises a plug 72 having flanges engaging the inside surface of the frame 12, a stop ring 74 mounted on the plug 72 on the outside of the frame 12 and a locking ring 76 threadedly engaging the plug 72. Hence, by rotating handle 78, the locking ring 76 may be tightened onto plug 72 such that stop ring 74 and plug 72 grip the frame 12 to prevent the rod 42 from being moved.

Conversely, the rod 42 can be released by rotating the handle 78 in the opposite direction.

Turning now to Figures 3A and 3B of the drawings, a locking device 100 according to the present invention is shown. More particularly, the locking device 100 comprises a knob 102 mounted on the rod 42 and a clamp 104. A hexagonal or toothed plate 106 is attached to the end of the rod 42 by means of a screw 108 and washer 110. The hexagonal plate 106 can be received in a recess 112 of the knob 102 such that rotation of the knob 102 causes the rod 42 to rotate.

In this way, the depth of cut of the saw blade 64 can be adjusted, as described above.

The clamp 104 comprises essentially the same components as described above, namely a plug 114, a stop ring 116 and a locking ring 118. In this embodiment, however, the locking ring 118 does not have a handle attached thereto.

In order that the locking ring 118 of the clamp 104 can be rotated, the knob 102 is slid along the rod 42 such that the hexagonal plate 106 disengages from the recess 112 and the opposite end of the knob 102 engages in a recess 120 in the locking ring 118. Within the recess 120 there are formed splines 122 which are engaged by splines 124 on the end of the knob 102. As a result, rotation of the knob 102 causes the locking ring 118 to rotate such that the clamp 104 is released. The angle of cut of the saw blade 64 can then be adjusted, as described above, without the rod 42 rotating (which would cause depth of cut of the saw blade to vary).

As a matter of interest, a pin 103 is a sliding fit in opposing bores of the stop ring 116 and plug 114. This first of all prevents one from rotating relative the other. Means (not shown) prevent either from rotating in the slot 44 so that both are therefore stationary and ring 116 has a pointer to indiciate the angle of bevel of the saw blade 64 on a scale 13 affixed to the face of frame 12. It should of course be pointed out that the pin 103 is not in the position shown in Figure 3A but is within the boundaries of the slot 44 out of the plane of the drawing in Figure 3A.

With reference to Figures 4A-4C, a second embodiment of locking device 200 according to the present invention is shown. In this embodiment, a knob 202 includes a recess 212 for receiving a hexagonal or toothed plate 206 as in the embodiment of Figures 3A and 3B. Accordingly, rotation of the rod 42 is effected in the same way as in the previous embodiment.

With regard to the clamp 204 of this second embodiment, plug 214 still incorporates flanges 215 for abutting the inside surface of the frame 12 and a threaded portion 216 for engaging a threaded portion 218 of a locking ring 220. However, in this embodiment a stop ring is not utilised, since the locking ring 220 includes an annular region 222 which abuts the outside surface of the frame 12 when the clamp 204 is gripping the frame 12.

Tightening and loosening of the locking ring 220 is still achieved by means of the knob 202 engaging the locking ring 220, but in this embodiment splines 224 on the side of the knob 202 engage corresponding splines mounted on inwardly extending flanges 226 of the locking ring 220. Hence, the locking ring 220 can be tightened onto the plug 214 to clamp the rod 42 in position, thereby fixing the angle of cut of the saw blade 64.

As seen in Figure 4B, the knob 202 can also engage the plug 214 directly. When this occurs, the external splines 224 ofthe knob 202 are received in a cavity 228 defined by the locking ring 220 so that the splines 224 do not engage any part of the locking ring 220. The knob 202 does, however, also include either a shaped end or splines 230 on its end which are received in a corresponding shaped or splined recess 231 in the plug 214, as seen in Figure 4B. By virtue of this mating of the knob 202 with the plug 214, rotation of the knob 202 causes the plug 214 to rotate. Since the plug 214 includes a gear 232 which engages a rack 233 on the frame 12, rotation of the plug 214 causes the plug 214 and hence the rod 42 to move along the slot 44 in the front wall of the frame 12. This in turn causes the angle of the saw blade 64 to vary for bevel cuts and the like.

When a desired angle of the saw blade 64 has been reached, it is simply necessary to withdraw the knob 202 from the plug 214 until the splines 224 engage the splines of the locking ring 220. The knob 202 can then be rotated to tighten the locking ring 220, thereby causing the locking ring 220 and plug 214 to clamp the frame 12 to retain the saw blade 64 at the desired angle. If desired, the knob 202 can be withdrawn further along the rod 42 until the hexagonal plate 206 engages the recess 212 in the knob 202. It is then possible to adjust the height of the saw blade 64 by simply rotating the knob 202 to rotate the rod 42.

A window 234 is provided in the frame 12 through which a scale 236 mounted on the end frame 38 can be viewed. The scale 236 indicates the angle at which the saw blade 64 is positioned. Such an arrangement facilitates accurate positioning of the saw blade 64 prior to cutting.

To facilitate alignment of the splines 224 of the knob 202 with the splines of the locking ring 220, a spring biased ball 238 is mounted in the knob 202. When the splines 224 are correctly aligned, the ball is received in a groove 240 in the rod 42. Hence, the knob 202 can simply be moved along the rod 42 until the ball 238 engages the groove 240 to achieve accurate alignment of the splines 224.

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.

Claims

1. A bevel table saw comprising a table supported by a frame, and a blade assembly mounted below the table and adapted to carry a saw blade which protrudes through a slot in the table to cut workpieces on the table, the blade assembly being pivotable about an axis parallel the slot to permit bevel cuts in the workpiece, wherein the degree of protrusion of the blade through the slot is adjsutable by rotation of a rod extending from said assembly through an arcuate slot in a front face of said frame, and pivoting of the blade assembly is effected by a user moving said rod along the arcuate slot, and wherein a knob is slidably mounted on the end of the rod and which, in a first position is non-rotatably fixed on the rod and in a second position is engaged with a clamp mounted on the rod and adapted to clamp the rod against pivoting about said axis.

2. A saw as claimed in claim 1, wherein the shaft carries a shaped end piece which engages a recess in the knob when the knob is in its first position.

3. A saw as claimed in claim 2, wherein the end piece is a plate having a plurality of sides which engages in the recess in the knob which is correspondingly shaped.

4. A saw as claimed in claim 3, wherein the plate is substantially hexagonal.

5. A saw as claimed in any preceding claim, wherein a portion of the knob is shaped to mate in its second position with a first part of the clamp such that the first part of the clamp can be rotated relative to a second part of the clamp to release the clamp.

6. A saw as claimed in claim 5, wherein the knob and the first part of the clamp mate via a plurality of interengaging splines.

7. A saw as claimed in claim 6, wherein interengagement of the splines of the knob and the first part of the clamp is facilitated by means of an alignment device acting between the knob and the shaft.

8. A saw as claimed in claim 7, wherein the alignment device is a biased ball which engages a recess on the rod when the splines of the knob and the first part of the clamp are engaged.

9. A saw as claimed in any preceding claim, wherein a second part of the clamp includes a cog engaging a rack in said arcuate slot, and wherein the knob includes a second portion which engages the second part of the clamp to enable the second part of the clamp to be rotated after the clamp has been released.

10. A saw as claimed in claim 9, wherein release of the clamp is achieved by means of splines on the outside of the knob engaging corresponding splines on a first part of the clamp, the splines on the knob being received in a cavity of the clamp when the knob engages the second part of the clamp.

11. A saw as claimed in claim 9 or 10, wherein the frame has a window through which a bevel angle scale can be viewed.

12. A bevel saw incorporating a locking device substantially as hereinbefore described with reference to and as shown in Figures 3A and 3B or Figures 4A, 4B and 4C of the accompanying drawings.