GB2203690A - Improvements in or relating to thicknessers - Google Patents

Abstract

A thicknesser guide assembly retains a planar mechanism 228 to allow the planer mechanism to be used to reduce accurately the thickness of a length of wood (or other suitable material). The assembly comprises a pair of side plates 2/2 which define a guide channel for the wood and also define vertical stops 230 for the planer mechanism which is retained between the guide plates in a manner to permit vertical movement only. Said vertical movement is limited by the stops 230 in one direction but is permitted in the other vertical direction by means of an elastic cord 223. The wood to be worked slides over the upper surface of an adjustable bottom member 218. The bottom member 218 is adjusted vertically by jacking screws 220 driven by internally threaded wheels interconnected by a belt (224, Fig. 6). The planer mechanism 228 may be an electrically powered portable hand tool. <IMAGE>

Description

"Improvements In Or Relating To Thicknessers This invention relates to thicknessers, and more particularly to guide assemblies facilitating the reduction in thickness of a length of wood (or other suitable material) to a predetermined value.

According to the present invention there is provided a thicknesser guide assembly comprising means for retaining a planer mechanism, guide means adapted to guide material to be planed into operative contact with the planer mechanism, said retaining means permitting vertical movement of the planer assembly relative to said guide means.

Further according to the present invention there is provided a thicknesser guide assembly comprising an opposed pair of side members whose inner faces are substantially planar and at a substantially fixed separation, an adjustable bottom member whose upper face is substantially planar and can be selectively adjusted to a predetermined position in a direction at right angles to said upper face, and a planer guide in the upper part of said guide assembly, said planer guide being shaped and dimensioned to accommodate a planer mechanism with lateral restraint but with limited freedom of vertical movement towards and away from said bottom member, movement of said planer mechanism towards said bottom member being ultimately limited in use by stops in the guide assembly while movement of said planer mechanism away from said bottom member is restrained in use by a resilient clamp which biases the mechanism within its guide in a vertical direction towards said bottom member, whereby the guide assembly in combination with a planer mechanism accommodated as aforesaid provides a longitudinal passage therethrough such that a length of wood or other appropriate material may be passed through the guide assembly to have its thickness reduced by the operating planer mechanism.

The planer mechanism preferably comprises a rotary cutter assembly rotating in use about an axis substantially parallel to the upper face of the bottom member and at right angles to the direction of movement of the wood (or other material) through the guide assembly. The cutter assembly is preferably driven by a suitable motor.

The rotary planer mechanism is conveniently in the form of an electrically powered portable hand tool temporarily incorporated into the guide mechanism to form an operating thicknesser. By way of example, the tool may be a Model DN 710 rotary plane as sold under the trade name "Black and Decker".

The planer guide may take the form of slots cut in the upper edges of the side members and each of a size just sufficient to allow the planer mechanism to be vertically inserted into the slots but without allowing significant horizontal movement. The stops which prevent movement of the planer mechanism down past a predetermined limit may take the form of ledges near the upper edges of the side members and upon which the planer mechanism sits in its lowest position. The resilient clamp which biases the planer mechanism vertically downwards within its guide may comprise one or more elastic cords tensioned over the planer mechanism to tether the mechanism with sufficient resilience to allow the mechanism to be lifted off the bottom stops by upward pressure from a length of wood whose current thickness exceeds the required final value of its thickness.

The adjustable bottom member is preferably coupled to the remainder of the thicknesser guide assembly by a coupling mechanism which automatically maintains the upper face of the bottom member substantially parallel to a nominal datum plane throughout the range of adjustment. Such a coupling mechanism may comprise a plurality of threaded jacking screws rotatably mounted on mutually parallel axes between the bottom member and the remainder of the guide assembly, with a mechanical drive linking each jacking screw for conjoint rotation such that rotation of one said screw produces substantially equal rotation of each said screw to cause equal adjustment of the adjustable bottom member at the connection points of each screw and thus to maintain the parallelism of the upper face of the adjustable bottom member.The mechanical drive may comprise a toothed belt linking a toothed pulley on each jacking screw.

The plurality of jacking screws may number two, a jacking screw being provided at each end of the bottom member. In an alternative embodiment, the plurality of jacking screws may number three and have non-colinear mounting points to give triangulated attachment of the adjustable bottom member to the remainder of the guide assembly.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is an end view of a thicknesser guide assembly in accordance with a first embodiment of the invention; Fig. 2 is a side view (partly cut away) of the assembly of Fig. 1; Figs. 3 and 4 are views, corresponding to Figs. 1 and 2, of a second embodiment of the invention; Fig. 5 is a perspective view of a further embodiment of the present invention; and Fig. 6 is a side sectional view of the embodiment of Fig. 5.

Referring first to Figs. 1 and 2, a thicknesser guide assembly consists of a elongated U-shaped channel 10 with two parallel side members 12 joined by an integral base 14.

The opposed inner faces 16 of the side members 12 are planar and at a fixed separation which define the sides of a longitudinal passage through the guide assembly. An adjustable bottom member in the form of an elongated strip 18 is mounted on the base 14 by means of jacking screws 20.

The screws 20, and hence the strip 18, are raised and lowered by nuts 22 whose exteriors are formed as toothed pulleys and linked by a toothed drive belt 24. The belt 24 ensures that rotation of one of the nuts 22 equally turns all of the nuts 22 and hence equally raises or lowers all of the screws 20. Thus, the strip 18 can be selectively raised or lowered relative to the base 14 while maintaining the upper surface of the strip 18 at all times parallel to the base 14.

The upper edges of the side members 12 have vertically-sided longitudinal cut-outs 26 (Fig. 2) which allow a planer mechanism schematically denoted in dashed outline 28 (Fig. 1 only; omitted from Fig. 2) to fit vertically into the guide formed by these cut-outs 26. The vertical edges of the cutouts 26 inhibit longitudinal movement of the planer mechanism 28 in the guide assembly 10 while forward and rear projections (not illustrated) on the planer mechanism 28 engage the inner faces of the side members 12 to prevent lateral movement of the planer mechanism 28. Ledges 30 formed on the inner faces 16 of the side members 12 function as stops to limit downward movement of the planer mechanism 28 to the position schematically denoted in Fig. 1.An elongated elastic cord 32 wrapped under suitable tension around the guide assembly channel 10 and over the planer mechanism 28 retains the mechanism 28 within the guide formed by the cut-outs 26 while permitting the mechanism 28 to rise off the bottom stops 30 under elastic restraint.

A keel strip 34 is fastened to the underside of the base 14 to facilitate securing of the channel 10 in a bench vice or other suitable clamp during use.

In operation of the thicknesser guide assembly shown in Figs. 1 and 2, the screws 20 are turned to bring the upper surface of the adjustable strip 18 to a distance below the stops 30 which is the intended final thickness of a strip of wood which is to be planed to size. The underside of the planer mechanism 28 (facing the upper surface of the strip 18) carries a high-speed rotary cutter which shaves off the upper surface of a piece of wood pressed against and passed along the underside of the cutter. Since the amount of wood that can be shaved off in a single pass is limited, the strip of wood to be thicknessed is passed repeatedly under the cutter until reduced to the required final thickness.

Unlike conventional thicknessers, no re-adjustment is required between each such pass, since the elastic cord 32 allows the cutter mechanism 28 to rise up each time the wood being presented to the cutter exceeds the cutting capacity.

A modified version of the embodiment of Figs. 1 and 2 is shown in Figs. 3 and 4.

In this embodiment the thicknesser guide assembly comprises two side plates 112 which are bolted onto a base member 114 which is in the form of a wooden block.

The upper ends of the side plates 112 are provided with respective flanges 113 which define the longitudinal passage through the guide assembly which receives the planer mechanism. The flanges 113 are maintained at a fixed separation by cross-ties 115. An adjustable bottom member 118 is adapted to be moved vertically between the side plates 112 by means of a jacking mechanism which comprises a number, in this case three, of internally threaded toothed wheels 122 interconnected by a toothed drive belt 124 and which may be rotated by means of a knurled wheel 125.

Rotation of the knurled wheel 125 effects rotation of all three of the toothed wheels 122 which in turn raise and lower jacking screws 120 which support the bottom member 118.

The embodiment of Figs. 5 and 6 is similar to the abovedescribed embodiments and comprises a U-shaped extrusion 210 which has a pair of side plates 212 and a bottom plate 214, the upper portions 213 of the side plates 212 define, in conjunction with ledges 230, vertical stops to limit downward movement of the planer mechanism 228 which is shown in dotted line.

An adjustable bottom member 218 is fixed on jacking screws 220 which are driven vertically by internally threaded, externally toothed wheels 222 which are interconnected by a toothed belt 224. The front wheel 222 may be rotated by a knurled hand wheel 225 to effect adjustment of the bottom plate 218.

Bottom portions 217 of the side plates 212 engage a support block 219. The bottom portions 217 are provided with retaining screws 221 which engage a shock cord 223 which retains the planer 228 against the ledges 230 whilst permitting vertical movement away from the ledges 230 during thicknessing.

Modifications and improvements may be incorporated without departing from the scope of the invention. For example, a shavings collection unit may be provided in the form of ducting from the planer into a shavings collection bag.

Such a unit may be desirable insofar as the thicknesser is adapted for fitment to a work bench.

Claims (11)

1. A thicknesser guide assembly comprising means for retaining a planer mechanism, guide means adapted to guide material to be planed into operative contact with the planer mechanism, said retaining means permitting vertical movement of the planer assembly relative to said guide means.

2. A thicknesser guide assembly comprising an opposed pair of side members whose inner faces are substantially planar and at a substantially fixed separation, an adjustable bottom member whose upper face is substantially planar and can be selectively adjusted to a predetermined position in a direction at right angles to said upper face, and a planer guide in the upper part of said guide assembly, said planer guide being shaped and dimensioned to accommodate a planer mechanism with lateral restraint but with limited freedom of vertical movement towards and away from said bottom member, movement of said planer mechanism towards said bottom member being ultimately limited in use by stops in the guide assembly while movement of said planer mechanism away from said bottom member is restrained in use by a resilient clamp which biases the mechanism within its guide in a vertical direction towards said bottom member, whereby the guide assembly in combination with a planer mechanism accommodated as aforesaid provides a longitudinal passage therethrough such that a length of wood or other appropriate material may be passed through the guide assembly to have its thickness reduced by the operating planer mechanism.

3. A thicknesser guide assembly as claimed in either Claiml or Claim 2, wherein said planer mechanism comprises a rotary cutter assembly rotating in use about an axis substantially parallel to the upper face of the bottom member and at right angles to the direction of movement of the wood (or other material) through the guide assembly.

4. A thicknesser guide assembly as claimed in any preceding claim, wherein said planer guide is in the form of slots cut in the upper edges of the side members and each of a size just sufficient to allow the planer mechanism to be vertically inserted into the slots but without allowing significant horizontal movement.

5. A thicknesser guide assembly as claimed in any preceding claim, wherein the stops which prevent movement of the planer mechanism down past a predetermined limit are the form of ledges near the upper edges of the side members and upon which the planer mechanism sits in its lowest position.

6. A thicknesser guide assembly as claimed in any preceding claim, wherein the resilient clamp which biases the planer mechanism vertically downwards within its guide comprises one or more elastic cords tensioned over the planer mechanism to tether the mechanism with sufficient resilience to allow the mechanism to be lifted off the bottom stops by upward pressure from a length of wood whose current thickness exceeds the required final value of its thickness.

7. A thicknesser guide assembly as claimed in any preceding claim, wherein the adjustable bottom member is coupled to the remainder of the thicknesser guide assembly by a coupling mechanism which automatically maintains the upper face of the bottom member substantially parallel to a nominal datum plane throughout the range of adjustment.

8. A thicknesser guide assembly as claimed in Claim 7, wherein a coupling mechanism comprises a plurality of threaded jacking screws rotatably mounted on mutually parallel axes between the bottom member and the remainder of the guide assembly.

9. A thicknesser guide assembly as claimed in Claim 8, wherein there is included a mechanical drive linking each jacking screw for conjoint rotation such that rotation of one said screw produces substantially equal rotation of each said screw to cause equal adjustment of the adjustable bottom member at the connection points of each screw and thus to maintain the parallelism of the upper face of the adjustable bottom member.

10. A thicknesser guide assembly as claimed in Claim 9, wherein the mechanical drive comprises a toothed belt linking a toothed pulley on each jacking screw.

11. A thicknesser guide assembly substantially as hereinbefore described with reference to the accompanying drawings.