WO2011104538A1

WO2011104538A1 - Guard means for a saw and method of use thereof

Info

Publication number: WO2011104538A1
Application number: PCT/GB2011/050347
Authority: WO
Inventors: Marcus Nicholson; Robert Firth
Original assignee: 7Rdd Limited
Priority date: 2010-02-26
Filing date: 2011-02-23
Publication date: 2011-09-01
Also published as: CN102811845B; GB201003262D0; CN102811845A

Abstract

Guard means are provided for a saw. A first part (16) of the guard means is movable relative to a body of the saw (4) and/or a saw blade (6) in use between a first position (figure 1), wherein at least a portion of the saw blade is substantially covered by the guard means, and at least a second position (figure 2), wherein at least a portion of the saw blade becomes exposed. The guard means further includes at least a second part (18) that is movable relative to said saw body and/or saw blade in use.

Description

Guard Means for a Saw and Method of use Thereof

The present invention relates to guard means for a saw, a saw including guard means and methods o f use thereof.

Although the following description relates predominantly to an electrically powered circular saw, whereby the circular saw blade rotates relative to a saw housing using an electrically powered motor in use, a person skilled in the art will appreciate that the features of the present invention can be used for other types of saw, such as a chain saw, manual saw, hand saw and/or the like.

The provision of a guard for a saw blade is known, and in particular the provision of a guard for a hand held electrically powered circular saw. A conventional guard is typically designed so that at least part of the guard can move between first and second positions in use. In the first po sition the guard typically covers, or provides a barrier around part of the cutting edge of the saw blade, thus preventing a user from accidentally contacting the blade. The guard typically remains in the first position covering at least part of the saw blade until the guard is brought into contact with a workpiece that is to be cut by the saw blade. On contact of the guard with a workpiece, at least part of the guard is moved, pushed, withdrawn, or otherwise retracted towards the rear of the saw blade, thereby exposing a larger portion of the saw blade to allow deeper and/or longer cuts to be made in the workpiece. The moving part of the guard is often resiliently biased towards the first position so that the blade is automatically covered by the guard when the blade and/or guard are removed from contact with the workpiece.

An example of a conventional circular saw with a movable guard is disclosed in US2008/0244910. The saw includes a body and a cutting head. A circular saw blade is coupled to the body and is arranged to be driven in a rotating manner by a motor in use. The cutting head includes an upper guard that covers an upper surface of the saw blade and a lower base plate. The cutting head and upper guard are pivotably j oined to the base plate. A lower guard portion is fixed to the lower base plate. As a user moves the tool body in a downwardly direction towards the workpiece in use, the cutting head and upper guard portion are pivoted towards the base plate. The lower guard portion moves upwardly within the upper guard portion until a depth of cut latch is engaged by the lower guard portion. When the tool is not in use, the combination of the upper and lower guard portions fully encloses the saw blade to prevent a user from accidentally coming into contact with the blade. The guard also functions to control dust and debris propelled from the workpiece by the saw blade in use. A vacuum or suction unit can be associated with the guard to aid dust extraction.

Whilst the above arrangement is generally satisfactory when the saw is brought into contact with the workpiece in the horizontal plane towards the workpiece, a number of problems are found with this arrangement when the saw is advanced towards the workpiece in a direction sub stantially out of the horizontal plane, and/or the first contact between the saw and the workpiece is at a location other than the front of the saw. This often occurs when the user wishes to perform a 'plunge cut' and/or a cut using the lower portion of the blade relative to the longitudinal axis of the saw. In order to do this, the guard must first be retracted manually by the user to expose the lower portion of the blade and then the saw blade is brought into contact with the workpiece. This is potentially a dangerous operation because a relatively large portion of the blade is exposed to the user before and during use, thereby increasing the likelihood of accidental contact between the blade and the user. In addition, the dust and debris created by this cutting process can be propelled from the saw blade in an uncontrolled manner.

It is therefore an aim of the present invention to provide guard means which addresses the abovementioned problems.

It is a further aim of the present invention to provide a saw with guard means which addresses the abovementioned problems.

It is a yet further aim of the invention to provide a method of use of guard means which addresses the abovementioned problems.

It is a yet further aim of the invention to provide a method of cutting a workpiece using a saw with guard means which addresses the abovementioned problems.

In a first aspect of the invention there is provided guard means for a saw, a first part of the guard means movable relative to a body of the saw and/or a saw blade in use between a first position, wherein at least a portion of the saw blade is sub stantially covered by the guard means, and at least a second position, wherein at least a portion of the saw blade becomes exposed, characterised in that the guard means includes at least a second part that is movable relative to said saw body and/or saw blade in use.

By providing the guard means with at least a second movable part, this allows the guard means to cover a greater proportion of the saw blade prior to or during use of the saw in a sub stantially downwardly direction relative to the workpiece, thereby allowing cuts sub stantially in the vertical axis and/or plunge cuts to be performed on the workpiece more safely. This is in contrast to the prior art guard disclosed in US2008/0244910 which has an upper guard portion fixed with respect to the saw body and blade and a lower guard portion that is movable relative to the upper guard portion, and thus movable relative to the saw body and/or blade (i.e. the prior art tool only has one guard portion that is movable with respect to the saw body and/or saw blade in use) .

Preferably the at least second movable part is movable with respect to the first movable part.

Preferably a sub stantial part of the saw blade is covered by the guard means in the first position and a covered part of the saw blade becomes exposed in the at least second position.

Preferably the first and at least second parts of the guard means form a substantially continuous housing or cover, such as for example a circular housing or cover when viewed from the side to house or cover a saw blade therein in the first position, and a gap is formed in the housing or cover on movement of the guard parts to the at least second position.

In the second position, the first and at least second guard parts are movable relative to one or more fixed parts of the saw body, the saw blade and/or a base plate of the saw and/or relative to one or more parts of the guard means that are fixed relative to the saw body, the saw blade and/or a base plate of the saw. This allows exposure or greater expo sure of a saw blade to a workpeice in use.

In a preferred embodiment the guard means includes at least four parts. Preferably two of the parts are fixed relative to the saw body, a base plate of the saw and/or a saw blade and preferably two of the parts are movable relative to the saw body, a base plate of the saw, fixed guard parts and/or to each other. In one embodiment the guard means and/or one or more parts of the guard means sub stantially surround, encircle and/or encase at least a cutting edge of a saw blade when in the first position. The cutting edge is typically provided along a peripheral or circumferential edge of the saw blade and preferably along a circumferential edge of a circular saw blade.

When the saw is being used to cut a workpiece and/or when the guard means is moved between the first and at least second positions, typically the entire cutting edge or at least part of the cutting edge of the blade above the workpiece is substantially covered, surrounded, encircled and/or encased by the guard means and/or one or more parts of the same.

In one embodiment the saw is of the type wherein the blade is rotatably mounted in respect of the saw body. Typically the saw is a powered saw, and preferably a powered hand held saw, such as a circular saw, mini-circular saw, plunge saw and/or the like. Reference to a mini-circular saw herein is a type of saw that is relatively light, thus making it portable and operable by a user using a single hand.

Typically the first position of the guard means corresponds to a storage position, out of use po sition, safety position and/or the like. In this first position at least part of, and preferably the entire cutting edge of the saw blade is prevented from contacting an object, workpiece or user.

Typically one or more of the movable parts of the guard means are slidably, rotatably, pivotally and/or retractably movable in relation to the saw body, saw blade a base plate of the saw body and/or one or more other parts of the guard means, such as a fixed part of the guard means in moving from the first position to the at least second position.

In one embodiment the guard means includes at least one fixed or non-movable part. Preferably the guard means includes at least two fixed or non-movable parts with respect to the saw body, a base plate and/or saw blade. The movable parts of the guard means are typically movable relative to the fixed part or parts of the guard means.

In one embodiment as the guard means is moved from the first position towards the at least second position a gap or space opens between at least two adjacent parts of the guard means. Preferably the gap or space opens between the second part of the guard means and a fixed part of the guard means. The gap or space allows part of the cutting edge of the blade to make contact with a workpiece in use.

In one embodiment the second part of the guard means is moved in a direction away from a fixed part of the guard means in moving from the first position to the second position. Preferably an edge or end of the movable part abuts, overlaps with or is adjacent to an edge or end of the fixed part in the first position and moves away or a spaced distance apart from said edge or end of the fixed point in the second position.

In one embodiment the first part of the guard means is moved towards or within a fixed part of the guard means, and/or within a part of the guard means that is fixed relative to the saw body, the saw blade and/or a base plate of the saw.

In one embodiment at least one movable part of the guard means is moved to overlap with or overlaps to a greater extent with a further movable part or fixed part of the guard means as the guard means moves from the first position to the second position.

In one embodiment the second movable part is slidably mounted to a base plate of the saw and movable with respect of the first movable part on movement of the guard means between the first and second positions in use. Preferably the second guard part is pivotably attached to the first guard part.

Preferably a protrusion or pin is provided on one of the base plate or second guard part that is slidably mounted in a slot provided on the other of the base plate or second guard part.

Preferably the second movable part is moved in a substantially radial direction with respect to the circular saw blade and/or along an axis substantially parallel to a longitudinal axis of a support, base or sole plate of the saw which is locatable on a surface of the workpiece in use.

In one embodiment the guard means is moved from the first position towards the at least second position by moving the saw body and/or the saw blade associated with the saw body towards a workpiece, base plate of the saw body or against an object in use. The saw body and/or the saw blade can be slidably, linearly, rotatably, and/or pivotally moved relative to the workpiece in use.

In one embodiment the guard means is moved from the first position towards the at least second position by bringing at least part of the guard means into contact with the workpiece or against an object in use.

In one embodiment the guard means and/or one or more parts thereof is resiliently biased towards the first position. In one embodiment one or more of the parts of the guard means create a channel or groove sub stantially within which the saw blade can move in use. Typically the channel or groove is sub stantially U-shaped. Preferably the saw blade can move within the channel or groove when the guard means is in any position. In this arrangement the saw can be started, wherein the saw blade begins to move relative to the saw body, whilst the guard means covers at least the cutting edge of the saw blade in the first position.

In one embodiment the saw includes a saw body and a base plate means, support means or sole plate. Typically the base plate means sits, or is located on, a surface of a workpiece in use. Further typically at least part of the base plate means is located sub stantially between at least one part of the guard means and the workpiece in use.

Preferably the saw includes an upper guard part that is fixed with respect to the saw body, an upper guard part that is movable with respect to the saw body, a lower guard part that is fixed with respect to the base plate and a lower guard part that is movable with respect to the base plate.

The at least second part of the guard means typically moves relative to the support means, base support means or sole plate in moving between the first and second positions.

In one embodiment the support means, base support means or sole plate provides a location to which the saw body can be movably attached and/or mounted to. The saw body can be slidingly, pivotally and/or rotatably attached to the support means, base support means or sole plate. Thus, in one embodiment a part of the guard means that is fixed relative to the saw body can be movably mounted on the support means, base support means or sole plate.

In one embodiment a part of the guard means that is fixed relative to the saw body is movably mounted to a rear end of the support means, base support means or sole plate. Preferably said fixed part of the guard means is pivotably mounted to the rear end of the support means. Thus, part of the guard means can be fixed relative to the saw body but movable relative to the support means, base support means or sole plate.

In one embodiment the support means, base support means or sole plate includes a slot, channel, notch and/or the like, which defines a window through which, at least part of the saw blade can pass to cut a workpiece in use.

In one embodiment the saw body is pivoted and/or rotated about a point to bring the saw blade into contact with a workpiece in use. Typically the point about which the saw is pivoted is the point at which the saw body and/or at least one part of the guard means is attached to the support means, base support means or sole plate.

Further typically the point about which the saw body is pivoted and/or rotated is located substantially towards the rear of the support means, base support means or sole plate.

In one embodiment at least a portion of the support means, base support means or sole plate forms part of the guard means, and preferably a lower part of the guard means.

In one embodiment at least one of the movable parts of the guard means is slidingly mounted on a portion of the support means, base support means or sole plate in use. In a preferred embodiment, as the saw body is moved towards an in-use po sition with respect to a workpiece, at least two adjacent parts of the guard means substantially slide apart. Typically at least one of the two parts slides away from the other part on the workpiece in use, and/or is slidably mounted to the support means, base support means or sole plate.

In one embodiment the guard means includes depth of cut indication means. Typically at least one of the fixed or stationary parts of the guard means includes the depth of cut indication means. Further typically the depth of cut indication means prevents, limits and/or restricts the movement of at least one of the movable parts of the guard means in relation to the saw blade, saw body, fixed guard part and/or adjacent part of the guard means.

Typically the depth of cut indication means regulates and/or determines the depth of cut of the saw blade in the workpiece by restricting the movement of the one or more movable parts of the guard means towards at least the second position.

Typically the depth of cut means prevents or limits one part of the guard means sliding in relation to an adjacent part.

In one embodiment the saw body includes a handle portion, gripping means and/or the like to allow a user to grip or hold the saw.

In one embodiment the saw and/ or guard means includes locking means. Typically the locking means sub stantially prevents the guard means being moved from the first position to the second position. Preferably resilient biasing means are provided to bias the guard means and/or the saw body from the second position to the first position.

In one embodiment the guard means includes dust extraction means. Typically the dust extraction means includes an aperture which is defined in one or more of the parts of the guard means. The aperture is preferably located substantially adjacent to a leading, front or cutting edge of the saw blade and/or guard means in at least the first and/or second po sitions. Further typically dust and/or debris are extracted though the aperture using hose means, a vacuum unit and/ or the like.

Preferably the dust extraction means are associated with the second movable guard part.

The leading edge of the saw blade is the point at which the edge of the saw blade contacts the workpiece in use and is the location wherein the most amount of dust and debris is generated in use of the saw blade on a workpiece. As this location is typically at the front of the blade and/or tangential to the same, conventional circular saw guards do not cover this location, particularly when moving towards at least the second position. Thus, the arrangement of the parts of the guard means as disclo sed herein allow for more efficient dust and/or debris extraction.

Preferably the inwardly facing edges of the guard parts are sub stantially curved or arced in shape, to form a substantially circular edge of a housing or cover when the guard means is in the first position. Further preferably the outwardly facing edges of the upper movable guard part and the lower fixed guard part are substantially complementary in shape, such as for example curved or arced in shape, to the upper fixed guard part so as to allow movement of the upper movable guard part and lower fixed guard part within the fixed upper guard part in use.

In a further aspect of the invention there is provided a powered saw with guard means. The powered saw has power means for powering drive means. The drive means drives rotation of a saw blade in use. For example the power means can include a mains power supply, battery power, rechargeable battery power, solar power and/or the like. The drive means can include a motor and/or the like. Suitable gearing, mechanical linkage and/or the like can be provided between the power means, drive means and the saw blade.

In a second aspect of the invention there is provided guard means for a saw, wherein the guard means includes at least three parts which cover at least a portion of the saw blade in a first position, at least one part of said guard means movable between a first position and at least a second position relative to the saw body and/or saw blade, thereby exposing a greater portion o f the saw blade than when in the first position.

In a third aspect of the invention there is provided a saw including guard means.

In a further aspect of the invention there is provided a method of using guard means for a saw, said method including the steps of locating the guard means in a first position adjacent a workpiece in use; and moving the guard means from the first position to a second po sition, thereby causing first and at least second movable parts of the guard means to move relative to the workpiece, a saw body and/or saw blade associated with the guard means in use. According to an independent aspect of the present invention there is provided a saw including a body portion, a handle portion arranged to allow gripping of the same by a user in use, and a base plate locatable on a surface of a workpiece for supporting the saw in use, said body portion movably mounted to said base plate to allow movement of the body portion relative to the base plate between a first non-cutting position and a second cutting position, and wherein and said base plate, body portion and handle portion are arranged such that a longitudinal axis of the handle portion is sub stantially parallel to a longitudinal axis of the base plate in the first non-cutting position, and the longitudinal axis of the handle portion is raised to a sub stantially upwardly or transverse position or sub stantially non-parallel axis with respect to the longitudinal axis of the base plate in the second cutting position.

Movement of the handle portion from a lower or parallel position to an upper or substantially angled position with respect to the base plate when moving from a start or non- cutting position to a cutting position is substantially opposite to the handle movement of prior art tools and allows maintenance of a neutral position of a user's wrist when gripping the handle portion. Thus, the arrangement of the handle portion with respect to the base plate and tool body of the present invention provides an improved ergonomic effect and allows the tool to be operated by a single hand of the user. The po sition of the actuation switches for the tool on the handle portion also allows the tool to be operated by the digits of a single hand of the user (i.e. the same hand that grips the handle portion) .

Preferably the tool body is pivotably mounted to a rear end o f the base plate (i.e. and end closest to the handle portion of the tool) . This reduces the likelihood of "kickback" of the tool in use. Specific embodiments of the invention are now described with reference to the following figures wherein:

Figure 1 shows a perspective view o f the right hand side of a saw in accordance with one aspect of the invention;

Figure 2 shows a side view of the guard means and saw blade in accordance with one embodiment of the invention;

Figure 3 shows a side view of the saw and guard means with the guard means in a second cutting po sition.

Figures 4a-4d show side views of the saw and guard means in moving from a first non-cutting po sition in figure 4a to a second cutting position in figure 4d respectively;

Figure 5 shows a perspective view o f the left hand side of the saw and guard means respectively; and

Figure 6 shows a perspective view o f the left hand side of the guard means.

The following embodiment illustrates an example of a guard for a power saw, and specifically a hand held electrically powered circular saw, according to the present invention. The guard is arranged to cover at least the cutting edge of a saw blade attached to the saw in a storage or first position, and the guard is provided with at least two movable parts to limit the area o f the blade exposed to a user during a cutting or second position.

The two movable guard parts move relative to fixed guard parts of the guard to allow the cutting edge of the saw blade to make contact with a workpiece in the second position. This arrangement is particularly advantageous when using the saw in a substantially downward direction relative to the workpiece as it allows cuts to be made in the workpiece in sub stantially the vertical axis and/or plunge cuts to be performed on the workpiece more safely.

Turning firstly to figure 1 , there is shown a perspective view of a hand held circular power saw 2. The saw includes a body or housing 4 which encases drive means in the form of an electrically powered motor (not shown) . The saw 2 in this embodiment is typically powered by mains electricity but the person skilled in the art will appreciate that the saw could equally be battery powered or powered by any other suitable electrical means. The motor drives rotation of a circular saw blade 6 in use.

The saw shown in figure 1 is in a first 'safety' position wherein the cutting edge of the blade 6 is encircled by a guard 8 preventing side access to the cutting edge of the blade. This arrangement ensures that the cutting edge of the blade 6 cannot accidentally come into contact with part of an object or user.

In the arrangement shown, the blade 6 can be actuated (i.e. the saw can be switched to an "on" condition to allow rotation of the blade relative to the housing 4) whilst the cutting edge of the blade remains completely encircled by the guard means 8 in the first position.

The saw is typically actuated by a user gripping a handle portion 10 of the housing 4 with one hand and pressing/pulling the on/off switch or trigger 12, typically with the index finger of the same hand. In this embodiment, the trigger 12 is located on a lower surface of the handle portion. The saw 2 in this example is also equipped with a base or sole plate 22. The base plate 22 is locatable on a surface of the workpiece to be cut in use and provides support for the saw during the sawing process. The base plate can be optionally equipped with one or more meters, rules, graduations and/or the like in order to assist in more accurate cutting and/or measuring angles, depths and/or lengths of cut. The base plate 22 can also be engaged with a track (not shown) on which the saw can be movably or fixedly mounted to increase the accuracy of sawing. The housing 4 of the saw is typically pivotably movable with respect to base plate 22 to allow the housing 4 and saw blade 6 to be moved from a first non-cutting position to a second cutting position, as will be described in more detail below

The guard 8 in this embodiment is divided into four sections or parts 14, 16, 18, 20. In the description two of the guard parts are referred to as major or upper guard parts 14, 16 in that they cover a substantial part of the saw blade 6, and typically an upper part of the saw blade, in use; two of the guard parts are referred to as minor or lower guard parts 1 8, 20 in that they cover less of the saw blade 6 relative to the major or upper parts 14, 16, and typically are provided to cover a lower part of the saw blade in use.

Upper guard part 14 is joined to and fixed with respect to housing 4 and handle 12 during use (i.e. remains stationary with respect to housing 4 and handle 12) . A base end 9 of upper guard part 14 is pivotably mounted to a rear end 1 1 (i.e. an end closest to handle 12) of base plate 22 via a pivot pin 24 to allow the housing 4, upper guard part 14 and handle 12 to be pivotably moved towards base plate 22, and thus a workpiece on which the base plate 22 is located on, in use. Upper guard part 14 is referred to a fixed guard part since it is fixed with respect to the tool/ saw body. Lower guard part 20 is joined to and fixed to base plate 22 (i. e. remains stationary with respect to the base plate), and typically is fixed adjacent to rear end 1 1 of the base plate. The lower guard part 20 protrudes upwardly from the base plate 22 towards housing 4. The longitudinal axis of guard part 20 in this embodiment is sub stantially parallel to the longitudinal axis of base plate 22. Lower guard part 20 is referred to as a fixed guard part since it is fixed with respect to the base plate. As upper guard part 14 is moved towards base plate 22, lower guard part 20 slidingly moves up inside guard part 14.

Upper guard part 1 6 is pivotably mounted to lower guard part 1 8 adjacent a front end 13 of upper guard part 16, and adjacent a front end 1 5 of lower guard part 18, via a pivot pin 17 (the front ends are typically the ends furthest from housing 4) . Thus, upper guard part 16 is movable relative to upper guard part 14 and housing 4, to lower guard part 18, and to base plate 22. Upper guard part 16, in this example, is arranged to slide inside the upper guard part 14 in use as the housing 4 and guard part 14 are moved towards the base plate 22, as discussed in more detail below. Upper guard part 1 6 is referred to as a movable guard part since it is movable with respect to the tool/ saw body, the lower guard part 1 8 and to the base plate 22.

Lower guard part 18 is slidably mounted to base plate 22 and is movable in a direction sub stantially parallel to the longitudinal axis of base plate 22. More particularly, when lower guard part 18 is moved from a first non-cutting position to a second cutting position, lower guard part 1 8 is moved away from rear end 1 1 of base plate 22 towards a front end 19 of base plate 22. Base plate 22 has a flange portion 21 protruding upwardly from an upper surface thereof towards housing 4. An elongate slot 36 is defined in flange portion 21 such that the longitudinal axis o f slot 36 is substantially parallel to the longitudinal axis of base plate 22. A part of pivot pin 1 7 or a further protrusion member is slidably mounted in slot 36 to guide sliding movement of lower guard part 1 8 between the first and second positions. Lower guard part 18 is referred to as a movable guard part since it is movable with respect to the tool/ saw body, to upper guard part 16 and to the base plate 22.

In use, when a user moves the saw from the first safety or non- cutting position shown in figure 1 , to a second cutting or sawing position as shown in figures 3 and 4d, the saw housing 4 and upper guard part 14 are pivoted about pin 24 towards base plate 22. This movement is achieved by a user gripping and raising the handle 10 relative to the workpiece and base plate 22. This causes upper guard part 1 6 to slide upwardly inside upper guard part 14, and causes lower guard part 1 8 to slide away from lower guard part 20 (i. e. lower guard part 18 moves towards a front end 1 9 of base plate 22) . In the first non-cutting po sition, a rear end 23 of lower guard part 1 8 abuts a front end 25 of lower guard part 20, thereby substantially enclosing circular saw blade 6. As the lower guard part 1 8 is moved to the second cutting position, a gap forms between ends 23 and 25 of lower guard parts 1 8, 20, thereby allowing the cutting blade to cut into the workpiece. A user has a good line of sight of the saw blade on separation of the guard parts 1 8, 20 whilst the cutting edge o f the saw blade is substantially protected from side access from above the base plate 22. In addition, movement of the lower guard part 20 and upper guard part 16 within upper guard part 14 in moving to the second position provides a compact guard structure, which has a smaller outer surface area visible to a user to that of the guard structure in the first position.

Further detail of how the guard 8 moves towards the second cutting or in-use po sition is shown in figure 2. In figure 2 the guard 8 is shown in a partially open position, with the cutting portion or edge of the blade 26 extending through an aperture in the base plate 22 and into a workpiece (not shown) . Partially open refers to the fact that the lower guard part 1 8 has slid forwards in direction A away from the lower guard part 20, which allows the upper guard part 1 6 to slide inside upper guard part 14, substantially in direction B. These movements are due to the turning force exerted by the user when the handle 10 (not shown in figure 2) is lifted and the guard part 14 pivots about pin 24 towards the base plate 22 substantially in direction C. Base end 25 of lower guard part 20 remains fixed on the base plate but an upper end (not shown) of the guard part 20 moves inside upper guard part 14, as the same moves down towards the base plate 22. In this arrangement the cutting edge 26 of the blade 8 above the base plate 22 remains covered by the guard at all positions moving from the first position towards the second in use position, where the blade 8 is exposed the maximum amount in this example.

The second in use or cutting position of the saw 2 is shown in figure 3. Here it can be seen that the handle 10 has been lifted away from base plate 22 to the fullest extent, wherein the upper guard part 14 has been pivoted about pin 24 and a lower edge 31 thereof abuts an upper surface of base plate 22. Upper guard part 1 6, and both lower guard parts 1 8, 20 lie substantially within the interior of upper guard part 14 and the saw blade 8 protrudes to the maximum extent though the base plate 22 and into the workpiece (not shown) .

Moving the handle 10 from the first non cutting position, wherein the longitudinal axis of the handle is positioned sub stantially parallel to the longitudinal axis of the base plate 22 in a sub stantially lowermo st position (the handle is in a position closest to base plate 22), to the second cutting position, wherein the longitudinal axis of the handle is positioned in an upwardly or upper most position (the handle is in a position furthest from base plate 22), moves the position of the handle to a more ergonomically favourable orientation for operation of the saw 2 as the user is able to exert more force, if required, and thus more control over the saw, particularly when pushing the same along the workpiece in a substantially horizontal direction and/or selecting the depth of cut. This is an advantage over traditional circular saws where a pivot point of the saw is located towards the front of the base plate and thereby the user has to pull the handle down from an upper position to a lower position in order to operate the saw.

The depth of cut (i.e. the depth at which the saw blade protrudes below the base plate 22), can be selected using depth means 28. A restricting bar (not shown) can be set by the depth means 28 which restricts the amount which the upper guard part 16 can move inside the upper guard part 14, thereby limiting the movement of the guard 8 and thus the depth to which the saw blade 6 can protrude below the base plate 22. Such a depth means restriction could also be placed on the sliding mechanism of the lower guard part 1 8 with respect to the base plate 22 to have the same effect. Movement of the guard, and thus the saw as a whole can be controlled by an interlock switch 30. The interlock switch 30 in this example is located towards the top of housing 4, between the housing and the upper guard part 14. The interlock switch is usually actuated by the users thumb and allows movement of the guard in the first instance. If the user is not ready to cut and does not have the interlock switch depressed, the saw 2 and the saw guard 8 remain in the first safety position, even if the saw blade 6 has been actuated by the trigger 12. Figures 4a-4d show the various positions of the guard 8 moving between the first safety position shown in 4a to the second full cutting po sition shown in 4d. It can be seen in figure 4a that the blade 6 is fully protected, even if the same is actuated, until the interlock switch 30 (not shown here) is pressed and the movable guard parts can move. Figure 4a-4d show how the guard parts 14-20 are moved relative to each other as the housing 4 and guard part 14 are rotated towards base plate 22 by the user about pin 24. Figures 4b-4c show how lower guard parts 18, 20 slide apart and how upper guard part 16 moves inside upper guard part 14, thereby exposing a part of the blade to cut the workpiece below the base plate 22. Figures 4a and 4d show how the section of the blade above the base plate 22 is covered throughout the range of motion right up to the full depth of cut. In this example the guard 8 is resiliently biased by a spring from the second position to the first position so that if the user releases the handle the movable guard parts springs back to the first safety position wherein the blade is completely encircled by the guard 8.

Figure 5 shows the right hand side of the saw 2 in the first safety po sition with the handle 10 orientated generally parallel to the base plate 22. A dust extraction aperture 32 can be seen in this view. The aperture 32 is located adjacent a front end 13 of upper guard part 16 and is optimally placed in this example by being adjacent at all times to a portion of the blade which first makes contact with the workpiece, thereby generating most of the dust during a cutting process. Whichever position the guard part 1 6 is in, dust and debris is continuously being extracted adjacent or substantially tangential to the point of the saw blade from which it is being generated. The walls of the aperture 32 and/or the inside surface of the upper guard part 1 6 can have one or more grooves and/or channels defined therein to control the flow of air to the upper guard part 16 and thereby optimise the extraction of dust and debris in the vicinity thereof. Typically a vacuum unit equipped with a hose is attached to the aperture 32 to provide suction to remove the dust and/or debris to a position remote from the saw blade.

Figure 6 shows the left hand side or rear of the guard 8 in more detail. It can be seen that the dust extraction aperture 32 is a sub stantially lozenge shape. The location and shape of aperture 32 is optimised to maximise dust collection irrespective of the various blade types and sizes that can be interchangeably used with the saw. The upper guard part 16 also has a protruding feature 34 forward of the pivot point 17 of the upper guard part 16 and lower guard part 1 8. The protruding feature ensures the upper guard part 16 remains parallel to the base plate 22 during movement thereof and prevents it from binding up. In this example there is one torsion springs (not shown) which biases the guard 8 to the first closed position. This figure also shows that an additional retaining quadrant or plate 38 has been added adjacent the rear end of guard 8 to ensure that the cutting head (housing 4, blade 6 and guard parts 14, 20) has stability and accuracy throughout the range of movement and cutting operation and throughout movement of the saw from the second cutting position to the first safety position.

It is to be noted that pivotal or rotational movement of one or the upper guard part 14 drives the linear movement of a further or lower guard part 18. This is because lower guard part 18 is in front of the direction of rotational movement of upper guard part 14 with respect to pivot pin 24.

Claims

1. Guard means for a saw, a first part of the guard means movable relative to a body of the saw and/or a saw blade in use between a first position, wherein at least a portion of the saw blade is sub stantially covered by the guard means, and at least a second position, wherein at least a portion of the saw blade becomes exposed, characterised in that the guard means includes at least a second part that is movable relative to said saw body and/or saw blade in use.

2. Guard means according to claim 1 characterised in that the at least second guard part is movable with respect to the first guard part in use.

3. Guard means according to claim 1 characterised in that the first and at least second guard parts form a substantially continuous housing or cover in the first position, and a gap is created in the housing or cover on moving the guard parts to the at least second position.

4. Guard means according to claim 1 characterised in that the first and at least second guard parts are movable relative to one or more fixed parts of the saw body, the saw blade and/or a base plate of the saw and/ or relative to one or more parts of the guard means that are fixed relative to the saw body, the saw blade and/or a base plate of the saw in use.

5. Guard means according to claim 1 characterised in that the guard means includes at least four parts; two of the parts are fixed relative to the saw body, saw blade and/or a base plate of the saw, and two of the parts are movable relative to the saw body, saw blade, base plate of the saw, fixed guard parts and/or to each other.

6. Guard means according to claim 1 characterised in that in the first position, an end or edge of a fixed guard part is in abutment with, adjacent to or in overlapping relationship with a movable guard part, and the ends or edges of the fixed guard part and the movable guard part are moved apart to form a gap therebetween in the at least second position.

7. Guard means according to claim 1 characterised in that the first and/or at least second movable guard parts are slidably, rotatably, pivotably and/or retractably movable relative to the saw body, saw blade, a base plate of the saw body and/or one or more other parts of the guard in moving from the first position to the at least second position.

8. Guard means according to claim 1 characterised in that the first and/or at least second movable guard parts are moved towards, within or in an increased overlapping relationship with respect to a fixed part of the guard means and/or towards, within or in an increased overlapping relationship with respect to a part of the guard means that is fixed relative to the saw body, the saw blade and/or a base plate of the saw in use in moving from the first position to the at least second position.

9. Guard means according to claim 1 characterised in that rotational movement of the first guard part drives sub stantially linear movement of the at least second guard part in moving from the first position to the second position in use.

10. Guard means according to claim 9 characterised in that the second guard part is slidably mountable to a base plate of a saw in use, and said second guard part is pivotably attached to the first guard part.

1 1. Guard means according to claim 10 characterised in that a protrusion or pin is provided on one of the base plate or second guard part that is slidably mounted in a slot provided on the other of the base plate or second guard part.

12. Guard means according to claim 1 characterised in that the guard means is provided on a saw, said saw including a saw body and a base plate for supporting the saw on a workpiece in use.

13. Guard means according to claim 12 characterised in that the saw includes an upper guard part that is fixed with respect to the saw body, an upper guard part that is movable with respect to the saw body, a lower guard part that is fixed with respect to the base plate and a lower guard part that is movable with respect to the base plate.

14. Guard means according to claim 12 characterised in that the saw body is pivotably movable with respect to the base plate via pivot means associated with one of the guard parts.

15. Guard means according to claim 14 characterised in that the saw body is pivotably mounted to a rear end of the base plate.

16. Guard means according to claim 12 characterised in that the guard means is moved from the first position to the at least second po sition by pivotably moving a part of the saw body and/or saw blade associated with the saw body towards the base plate and/or workpiece in use.

17. Guard means according to claim 1 6 characterised in that the saw body includes a handle portion and the handle portion is arranged to move in an upwardly direction away from the base plate on moving the saw from the first position to the second position.

18. Guard means according to claim 1 7 characterised in that the base plate, body portion and handle portion are arranged such that a longitudinal axis of the handle portion is substantially parallel to a longitudinal axis of the base plate in the first position, and the longitudinal axis of the handle portion is raised to a sub stantially upwardly, transverse position or non-parallel position with respect to the longitudinal axis of the base plate in the second position.

19. Guard means according to claim 1 characterised in that the guard means includes depth of cut indication means.

20. Guard means according to claim 1 9 characterised in that one of the fixed parts of the guard means includes the depth of cut indication means and said depth of cut indication means prevents, limits and/or restricts the movement of at least one of the movable parts of the guard means in relation to the saw blade, saw body, fixed guard part and/or adjacent part of the guard means in use.

21. Guard means according to claim 1 characterised in that the saw and/or guard means includes locking means for preventing movement of the guard means from the first position to the second position in use.

22. Guard means according to claim 1 characterised in that resilient biasing means are provided to bias the guard means from the second position to the first position in use.

23. Guard means according to claim 1 characterised in that the guard means includes dust extraction means.

24. Guard means according to claim 23 characterised in that the dust extraction means includes an aperture defined on a guard part adjacent a leading, front or cutting edge o f the saw blade and/or guard means in use.

25. Guard means according to claim 24 characterised in that the dust extraction means are provided on an upper movable guard part of the guard means.

26. A method of using guard means for a saw, said method including the steps of locating the guard means in a first position adjacent a workpiece in use; and moving the guard means from the first po sition to a second position, thereby causing first and at least second movable parts of the guard means to move relative to the workpiece, a saw body and/or saw blade associated with the guard means in use.