Adjustable featherboard

Abstract

The present invention relates to improvements in a magnetic featherboard, the featherboard having an elongate main body with opposite lateral faces, a bottom face and front and rear faces; a plurality of resiliently deformable feathers arranged at one or both lateral faces of the main body, and at least two, on-off switchable permanent magnets respectively received in one of at least two spaced apart recesses of the main body such that a working face of the respective switchable permanent magnet is present at the bottom face of the main body. One improvement comprises (i) providing a resiliently deformable friction gasket adjacent the working face of each of the switchable permanent magnets and protruding, in an non-deformed state, a predetermined amount from the bottom face of the main body and the working faces, the gaskets deformable through magnetic clamping of the featherboard to a table. The other improvement resides in providing at least two adjustable stops at one or both of the front and the rear face of the main body, each said stop comprising an abutment piece displaceable in longitudinal direction relative to the front/rear face, wherein a distance of each of the abutment pieces from the front/rear face is settable independently of each other, the stops operational to provide at least two abutments against which stock material to be machined can be placed when the featherboard is magnetically secured to the table.

Claims

1. An improvement in a magnetic featherboard, the featherboard having: an elongate main body with opposite lateral faces, a bottom face and front and rear faces; a plurality of resiliently deformable feathers arranged at one or both lateral faces of the main body, the feathers extending parallel to each other and angularly with respect to a longitudinal axis of the main body; and at least two, on-off switchable permanent magnets respectively received in one of at least two spaced apart recesses of the main body such that a working face of the respective switchable permanent magnet is present at the bottom face of the main body, the switchable permanent magnets being operative in an on-state to magnetically clamp the featherboard to a support table or a fence of a machine for cutting, routing or performing similar material-removing operations on stock material, the support table/fence having at least one groove formed in a stock-facing surface thereof, the improvement comprising: (i) providing a resiliently deformable friction gasket adjacent the working face of each of the switchable permanent magnets and protruding, in an non-deformed state, a predetermined amount from the bottom face of the main body and the working faces to stand the featherboard on the stock-facing surface of the table/fence, the gaskets deformable through magnetic clamping of the featherboard to the table/fence to an extent wherein abutment of the working faces of the switchable permanent magnets on the stock-facing surface of the table or fence is achieved whilst maintaining gasket engagement at the stock-facing surface, and (ii) selecting a shape and dimensions of the working face of the switchable permanent magnets to have a surface area that is larger by a predetermined amount than the square value of a width of the at least one groove formed in the stock-supporting surface of the support table/fence.

2. An improvement in a magnetic featherboard, the featherboard having: an elongate main body with opposite lateral faces, a bottom face and front and rear faces; a plurality of resiliently deformable feathers arranged at one or both lateral faces of the main body, the feathers extending parallel to each other and angularly with respect to a longitudinal axis of the main body; and at least two, on-off switchable permanent magnets respectively received in one of at least two spaced apart recesses of the main body such that a working face of the respective switchable permanent magnet is present at the bottom face of the main body, the switchable permanent magnets being operative in an on-state to magnetically clamp the featherboard to a support table of a machine for cutting, routing or performing similar material-removing operations on stock material, the improvement comprising at least two adjustable stops at one or both of the front and the rear face of the main body, each said stop comprising an abutment piece displaceable in longitudinal direction relative to the front/rear face, wherein a distance of each of the abutment pieces from the front/rear face is settable independently of each other, the stops operational to provide at least two abutments against which stock material to be machined can be placed when the featherboard is magnetically secured to the table.

3. The improved featherboard of claim 2, wherein each of the at least two adjustable stops comprise a spindle member at one terminal end of which the associated abutment piece is carried.

4. The improved featherboard of claim 3, wherein the spindle member has an externally threaded distal portion and a non-threaded proximal portion with a guide element, the spindle member being received in a respective passageway at the main body with the guide block disposed to allow to and fro movement whilst restraining rotation of the spindle member during said to and fro movement.

5. The improved featherboard of claim 4, wherein each of the at least two adjustable stops further comprise an adjustment member threaded to the threaded distal portion of the spindle and secured in a manner which allows rotation of the adjustment member about an axis of the spindle member but prevents axial displacement along the spindle axis and with respect to the front/rear face of the main body, wherein selective rotation of the adjustment member is operative to change a distance by which the abutment piece stands proud from the front/rear face.

6. The improved featherboard of claim 4, wherein the spindle member comprises a square-head bolt, with the head providing the guide element, and a bearing element securing axially-unrestricted movement and support of the bolt's proximal portion at the main body.

7. The improved featherboard of claim 6, wherein a helical compression spring locates between the bearing sleeve and a rearward facing face of the adjustment member so as to restrict axial movement of the adjustment member as it is rotated.

8. The improved featherboard of claim 5, wherein the adjustment member is one of a knurled thumb nut and a hexagonal nut.

9. The improved featherboard of claim 1, wherein the friction gaskets are devised to partially or fully surround the working faces of the switchable permanent magnets.

10. The improved featherboard of claim 1, wherein the working faces of the switchable permanent magnets have one of a circular, oval or rectangular configuration.

11. The improved featherboard of claim 1, wherein the friction gaskets comprise discrete tubular compressible gasket rods which locate and are respectively fixed in a respective one of four grooves in the bottom face, one said groove respectively adjoining a front and a rear side edge of each of the two cavities in which the switchable permanent magnets are received.

12. The improved featherboard of claim 10, wherein the friction gaskets comprise discrete tubular compressible gasket rods, and the discrete tubular compressible gasket rods have a diameter that ensures, when snuggly fitted into the respective grooves, the rods protrude and stand proud of the plane defined at the bottom face of the main body part, and wherein the gasket rods are made of a friction-enhancing, compressible rubber material and are compressible to an extent that when fully compressed into the respective grooves, they no longer stand proud, but create a substantially continuous planar surface with the working face of the switchable permanent magnets when the latter are turned into an on (magnetized) state when the featherboard is received on the table.

13. The improved featherboard of claim 1, wherein the shape and/or specific dimensions of the working face of the switchable permanent magnets is chosen such that the working face area is one of at least 50% and at least 100% larger than the square of the width of the miter slot of the machine table/fence on which the featherboard is intended to be used.

14. A magnetic featherboard comprising: a main body with opposite lateral faces, a bottom face, a front face, and a rear face; a plurality of resiliently deformable feathers arranged on at least one of the lateral faces, the feathers extending nominally parallel to each other and angled relative to a longitudinal axis of the main body; at least one recess positioned within the bottom face; at least one switchable permanent magnet received within the at least one recess, and a working face of the permanent magnet is adjacent the bottom face; a resiliently deformable friction gasket adjacent the working face of each of the at least one switchable permanent magnets, the resiliently deformable friction gasket configured to protrude, in a non-deformed state, a predetermined amount from the bottom face of the main body, and the resiliently deformable gasket further configured to deform through magnetic clamping of the featherboard; and at least two adjustable stops positioned on at least one of the front and the rear face of the main body, the adjustable stops each comprising an abutment piece longitudinally displaceable.

15. The improved featherboard of claim 6, wherein the bearing element is a bearing sleeve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic and perspective view of a featherboard, as per the prior art, illustrated in use on a table saw;

(2) FIG. 2 is a perspective view from above a featherboard embodying various improvements proposed by the present invention;

(3) FIG. 3 is a perspective view, from below, of the featherboard of FIG. 2;

(4) FIG. 4 is a perspective exploded view of the featherboard of FIG. 2 showing its constituent components; and

(5) FIG. 5 is a schematic illustration showing how a groove can be formed in a single square-section wood beam using the featherboard of FIG. 2 by virtue of the two adjustable stops provided on a front face of the featherboard.

DESCRIPTION OF PREFERRED EMBODIMENT

(6) The present invention is concerned with improvements to existing featherboard designs, in particular featherboards with a magnetic clamping mechanism. Noting that FIG. 1 has already been referred to in the introductory part of this specification in describing nature and use of featherboards generally, the skilled person can notionally exchange the prior art featherboard 22 illustrated in FIG. 1 with the featherboard 30 described below with reference to FIGS. 2 to 5, in performing timber stock machining/cutting operation as previously described, with the added benefits which the use of magnetic featherboards entail as regards of freedom of positional placement on the machine table 12 and fixing of such position without the need to cooperate with existing miter slots 16/17.

(7) Referring then to FIGS. 2 to 4, the improved featherboard 30 includes a main elongate body 32 cast from a suitable hard/wear-resistant plastic material, such as ABS or reinforced nylon or similar polymer, defining a rigid box-like, preferably partially hollow structure with internal webs joining external front, rear, side and top body walls. Body 32 has parallel opposite lateral faces 34, 36, a discontinuous bottom face 38, planar front and rear faces 40 and 42 and a substantially closed top face 44 on which two, rotatable actuator knobs 62 stand proud on longitudinally opposite ends of the featherboard 30.

(8) Twelve resiliently flexible fingers (ie feathers 46, 48) are integral with and cantilevered on both lateral faces 34, 36 of elongate body 32, the plurality of feathers 46 and 48 on each lateral face 34, 36 and extending parallel to each other with small spacing between them. It will be seen that the feathers 46 on side face 34 are angularly inclined (counting counter-clockwise along a longitudinal axis X of elongate body 32 in direction from rear to front face) at between 45 and 80 degrees (typically 65 to 75 degrees) with respect to longitudinal axis X, and the feathers 48 on side face 36 are inclined by the same angular value but counted clockwise. In other words, a featherboard 30 design is provided which enables it to be deployed on both sides of a saw blade in performing its feathering function as was described with reference to FIG. 1.

(9) For example, the featherboard may comprise an elongate main (or central) body portion 32 with a length of 175 mm between front and rear terminal faces 40, 42, a width of 40 mm between opposite lateral faces 34, 36 (ie excluding the plurality of elastically deformable feathers/fingers 46, 48 which would be typically angled 60° with respect the longitudinal axis X of the featherboard and protrude another 30-35 mm from both side faces), and have a height of 55 mm.

(10) As best seen in FIGS. 3 and 4, featherboard 30 has two, on-off switchable permanent magnet units 50, 52 fittingly locating in rectangular cavities 57, 58 respectively formed near the front and rear longitudinal ends of central body portion 32, the cavities 57, 58 being open towards the bottom face 38. The on-off switchable permanent magnets 50, 52 are, the illustrated embodiment, modified AR20-type switchable permanent magnet units as manufactured and sold by the applicant; for more information about magnetic specifications please access http://www.magswitch.com. One modification associated with the proposed improvement resides in a modified, T-stepped housing 54 which is comprised of two, opposite polarizable, appropriately machined pole shoes which provide an enlarged magnetic pole footprint area (ie at the working gap face 56 of a magnet unit 50, 52; see FIG. 3) as compared with a traditional rectangular box-shaped, non-stepped housing. As will be noted, the footprint area here substantially takes up the entire width (minus sidewall thickness) of the central body 32 of featherboard 30, ie approximately 36 mm using the dimensions noted above. Each magnet unit 50, 52 has an extension (in longitudinal axis direction) of around 15 mm. These dimensions are exemplary only. One improvement vs Magswitch's existing Magnetic Universal Featherboard Model 8110015 resides in the substantially enlarged working face area 56 provided by and at the terminal ends of the pole pieces of the housing 54, without reducing magnet holding force to any detrimental extent.

(11) Each magnet unit 50, 52 is secured inside the respective cavity 58 using four M3x05x12 BHSCS screws 59 which extend through respective through holes in the top face wall of central body part 32 and locate in threaded bores 55 on an upper face of T-shaped housing 54. A rotatable torque plunger 60 is rotationally fixed to actuator knob 62 and extends through another through hole 64 in the top face of elongate main body 32 to engage and mechanically couple with an upper, rotatable cylindrical, permanent magnet 66 of magnet unit 50, 52, thereby allowing torque transmission to rotatable magnet 66 upon rotation of knob 62 to turn-on and turn-off the magnet units 50, 52, and thereby magnetically fix/attach/clamp (and release the engagement of) the featherboard 30 to/from the table of the table saw (as per FIG. 5).

(12) Referring again to FIGS. 3 and 4, it will be noted that a respective tubular (cylindrical) compressible gasket rod 68, 70 locates and is fixed (eg glued) in a respective one of four grooves (not illustrated in detail) extending between the side faces 34, 36 in the bottom face 38 adjacent a front and rear edge of each cavity 58 in which the magnet units 50, 52 are received. The rods 68, 70 have a diameter that ensures, when snuggly fitted into the respective grooves, the rods 68, 70 protrude and stand proud of the plane defined at the bottom face 38 of central main body part 32. On the other hand, the rods are made of a friction-enhancing, compressible rubber material, and are compressible to an extent that when fully compressed into the respective grooves, they no longer stand proud, but create a substantially continuous planar surface with the working face 56 of magnet units 50, 52 when the latter are turned into the on (magnetized) state when the featherboard 30 is received on a saw table 12, thereby enabling magnetic coupling/clamping of the featherboard 30 to the support table 12 of the saw table 12. The gasket rods 68, 70 provide friction enhanced grip between featherboard 30 and the surface of the support table 12, beyond the magnetically induced Normal force securing the magnets (at working gap face 56) to the saw table 12.

(13) Turning next to FIGS. 2 to 5, a further functional improvement is made to featherboard 30 by providing at its front face 40 two independently adjustable abutment stops 72, 74 that are constructionally identical to one another and which telescope in retractable manner parallel to one another along the longitudinal axis X of the main body part 32. The stops 72, 74 provide separate abutments/distance stops against which stock material 20 to be machined can be placed when the featherboard 30 is magnetically secured to the surface s of the saw table 12, as may be gleaned from the schematic illustration of FIG. 5, when performing cross-cut operations on timber (or plastic/aluminum) stock material, eg when cutting a notch or groove in the stock material 20. A cross-cut is normally defined as a cut wherein the plane of a cut is perpendicular or inclined with respect to a main extension of a stock material when pushed as per arrow B against a stop, as compared to eg rip cut, where the cut plane is parallel with a guide fence along which stock material is fed, as illustrated in FIG. 1 by arrow A.

(14) Each stop 72, 74 includes an abutment piece 76 comprised of a peripherally knurled disc portion and a central hub portion having an internal thread. Each abutment piece 76 is held displaceable in longitudinal direction relative to the front face 40. The spacing (axial distance d1, d2) of each abutment piece 76 from the front face 40 is settable independently of each other using a respective drive spindle arrangement. 78. The latter comprises a spindle member 80 (see FIG. 4) having an externally threaded distal portion 82 and a non-threaded proximal portion 84 with a rotation-inhibiting guide element 85. The abutment piece 76 is threaded onto the terminal end of threaded spindle portion 82.

(15) The spindle member 80 is received through opening 87 in front face 40 in a respective passageway at the main elongate body 32, with the guide element 85 cooperating with a counterpart guide structure within main body part 32 to allow to and fro movement whilst restraining rotation of the spindle member 80 during said to and fro movement.

(16) Each drive spindle arrangement. 78 further comprises a rotatable distance adjustment member in form of a knurled thumb nut 90 threaded onto the threaded distal portion 82 of the spindle 80, and secured in a manner which allows rotation of the thumb nut 90 about the spindle but prevents axial displacement along the spindle axis and with respect to the front face 40. To this end, a collard bearing sleeve 86 is secured in through hole 87 and provides support of the spindle's proximal (smooth) portion 84 at the main elongate body 32, whilst a helical compression spring 88 locates about the distal, threaded portion 82 between the bearing 86 and a rearward facing side of the adjustment thumb nut 90 in order to restrict axial movement of the adjustment member 90 during manual rotation to change a distance d1, d2 by which the abutment piece 76 stands proud from the front face 40.

(17) In the embodiment illustrated, the spindle 80 is provided by a square-head bolt, with the head providing the rotation restricting guide element 85 of the spindle.

(18) The cooperating threaded portion 82 of the spindle 80 and adjustment member 90 are chosen in a manner whereby one full 360° turn of the adjustment member 90 equates with a specific linear distance travelled by the associated abutment piece, eg one full rotation equates with 0.4 mm displacement, but any suitable thread pitch may be chosen. This allows the two stops 72, 74 to be individually micro-adjusted to provide separate stops for repeatable cross-cut sawing operations on stock material and precise cutting of slots of a desired width in a same and additional stock materials, without a need to separately measure for correct slot-width and location, and re-adjustment of a single stop element.

(19) Such operation is illustrated schematically in FIG. 5, where the circular saw disc 10 of the table saw is shown in top plan view and extending through slot 14 in the surface s of table 12. The featherboard 30 is (incorrectly) shown in perspective view rather than plan view, but this is not relevant in this context. Relevantly though, featherboard 30 is magnetically clamped to the saw table surface s, with the stops 72/74 (or rather, the front face 40 of the featherboard 30) at a desired lateral spacing from saw blade 10, dictated by the approximate location of where a cross-cut is to be effected in the stock material 20 which is to be fed positionally held in direction c towards blade 10 using a not-illustrated pushing block. Stop 72 is shown with its abutment piece 76 protruding a distance d2 from the front face 40 of featherboard 30, whereas stop 74 has its abutment piece 76 spaced a smaller distance d1 than that of stop 72. For present purposes it is assumed that lower stop 74 distance d1 has been adjusted so that abutment of stock material against its abutment piece 76 is intended to provide a left-hand edge Le of an intended wider slot to be cut into the stock material 20. Distance d2 can then be set to correspond with the right hand edge Re by adjustment of the abutment piece 76 of upper stop 72 and thus define a gap distance dg. Timber stock material 20 is then first abutted against the lower stop 74 as illustrated in the phantom outline, then moved along direction c whilst maintaining its stop-defined position (the featherboard 30 remains stationary), to make the first cross-cut, then retracted from the saw to be placed with its terminal end against upper stop 72 and then pushed again against the saw 10 to make a second notch parallel with a spacing of dg with respect to the first notch cut; subsequent passes to remove material between the cut notches then creates a groove located between the two axial cut edges Le and Re of the notches.

(20) If for whatever reason the machined groove is undersized for its intended purpose, adjustment of d1, d2 or both can be carried out to widen dg.

(21) While the form of apparatus herein described constitutes a preferred embodiment of this invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention.

REFERENCE SYMBOLS USED IN THE DRAWINGS

(22) 10 saw blade 12 saw table 14 blade slot 16 miter slot in support surface s of saw table 12 17 guide/fastening groove in support surface s of saw table 12 18 rip/guide fence 19 rip fence T-groove 20 stock material 22 prior art featherboard 24 fingers/feathers of prior art featherboard 22 26 fastening/clamping screws of prior art featherboard 22 28 adjustment slots in body of prior art featherboard 22 30 improved magnetic featherboard 32 elongate main body part X its being longitudinal axis 34, 36 opposite (width-ward) side faces 38 bottom face 40 axially front face 42 axially rear face 44 top face 46 feathers on side 34 48 feathers on side 36 50, 52 on-off switchable permanent magnet units 54 T-shaped housing of 50/52 55 threaded fastening bores in upper face of 54 56 working (gap) face of magnet unit 50/56 57, 58 cavity in main body part 32 opening towards bottom face 38 59 fastening bolts attaching magnets 50/52 to main body part 32 60 rotatable torque plunger of 50/52 62 actuator knob rotationally fixed to plunger 60 64 through hole for 60 66 rotatable magnet of 50/52 68 axially rear magnet gasket rods 70 axially front magnet gasket rods 72, 74 abutment stops 76 abutment piece of 72/74 78 spindle drive mechanism 80 spindle 82 threaded distal spindle end 84 non-threaded proximal spindle end 85 guide element 86 bearing sleeve 87 through hole in wall at front face 40 of block 32 88 helical compression spring 90 adjustment member/thumb nut