Serrated blades and bladed tools

Abstract

A tool blade (100) comprises an exposed serrated cutting edge (101) and a first line of weakness (102) behind the exposed serrated cutting edge (101) and spaced from the exposed serrated cutting edge, the line of weakness (102) being shaped to provide a second serrated cutting edge when the blade (100) is snapped along the line of weakness. The tool blade (100) may be a saw blade (100), and / or the spacing between a forward-most point of the exposed serrated cutting edge (101) and a forward-most point of the second serrated cutting edge (102) may be at least 2 mm. Tools including such blades 100, and tools for snapping such blades (100) along a line of weakness (102), are also provided.

Description

[0001] SERRATED BLADES AND BLADED TOOLS

[0002] The present invention relates to serrated blades for use in cutting tools, and to tools incorporating such blades, for example, jig saws, hand tools (i.e. tools held in the hand and operated without electricity or other power), and oscillating cutting tools (such as powered tools often referred to as multi-tools). In particular, the invention relates to blades with multiple available cutting edges such that a worn or blunt cutting edge can be snapped off the blade to reveal a new cutting edge for use. A tool for snapping off a blade portion so as to reveal a new cutting edge is also disclosed.

[0003] Blades inevitably wear and become blunt with use. A worn or otherwise damaged blade will be thrown away, and, although it might be recycled, a lot of material and cost is wasted. For multi-tools in particular, typically the tool comprises a blade assembly in two parts - an attachment section which includes an attachment formation to mate with the oscillating tool, and a blade section which includes the cutting blade. The two parts are welded together and when the blade section is worn, the whole assembly is discarded. Similarly, blades in many kinds of tool have an attachment portion integral with, or permanently connected to, the blade, such that it is not just the sharpened part which is disposed of once worn. A large volume of waste is therefore generated.

[0004] It is an object of the present invention to provide a blade for a cutting tool which can be used for longer to reduce waste.

[0005] According to a first aspect, there is provided a blade comprising an exposed serrated cutting edge and at least one line of weakness behind, and spaced from, the exposed serrated cutting edge, the line of weakness being shaped to provide a second serrated cutting edge, the second serrated cutting edge being provided / made available for use when the blade is snapped along the line of weakness.

[0006] The blade may not be a straight-edged blade for an oscillating tool (also referred to as a multi-tool). For example, the blade may be a blade of any shape for a hand tool, or may be a round oscillating blade for a multi-tool.

[0007] According to a second aspect, there is provided a tool blade comprising an exposed serrated cutting edge and a first line of weakness behind the exposed serrated cutting edge and spaced from the exposed serrated cutting edge, the line of weakness being shaped to provide a second serrated cutting edge when the blade is snapped along the line of weakness, and wherein the spacing between a forward-most point of the exposed serrated cutting edge and a forward-most point of the second serrated cutting edge is at least 2 mm.

[0008] The tool blade may be a (non-powered) hand tool blade.

[0009] The tool blade may be a saw blade. The blade may be as described with respect to the first aspect.

[0010] According to a third aspect, there is provided a saw blade comprising an exposed serrated cutting edge and at least one line of weakness behind, and spaced from, the exposed serrated cutting edge, the line of weakness being shaped to provide a second serrated cutting edge when the blade is snapped along the line of weakness.

[0011] The blade may be as described with respect to the first or second aspect.

[0012] For any preceding aspect:

[0013] The blade has a serrated front edge for use in cutting. After a period of use, the serrated front edge will become worn / blunt. At that point, a front portion of the blade can be snapped off along a / the line of weakness. A new serrated edge will then be revealed at what is then the front of a slightly smaller blade. Forward-facing points along the line of weakness form the serrations of the new serrated edge. The line of weakness definiens multiple at least substantially forward-facing points, along the length of the cutting edge.

[0014] Different designs of serrations are useful to effectively cut through different materials, e.g. metal, dry wood, green wood, plastics, etc., and the shapes, sizes, spacings, and angles of serrations may be chosen accordingly.

[0015] The line of weakness may be weaker at and around the forward-facing cutting point of each serration, and stronger in troughs between adjacent serrations. This may facilitate providing sharp cutting points.

[0016] The line of weakness may comprise a series of alternating weakened portions arranged to facilitate snapping of the blade along the line of weakness, and stronger connecting portions arranged to keep the parts of the blade connected until it is desired o snap one off. The connecting portions may be in the trough between teeth (serrations). Every tooth tip may have a weakened portion - optionally in the form of a gap / cut-away portion of the blade - around it, to ensure the tips remain sharp and keep their shape. The weakened portion may extend around at least the forward-most 10%, 20%, 30%, 40%, or 50% of the tooth’s height. Additionally or alternatively, a weakened portion may extend to a forward-facing point at one end of the line of weakness, which may be at a lateral edge of the blade. This may ensure a clean break, and optionally a sharp corner, at the end of the line of weakness. The same may apply to each end of the line of weakness.

[0017] An average thickness of material forming the blade along the or each line of weakness may be lower than an average thickness of the material forming the blade adjacent to the or each line of weakness. The tool blade may further comprise additional lines of weakness behind the first line of weakness. Each additional line of weakness may be shaped to provide a further serrated cutting edge when the blade is snapped along the line of weakness.

[0018] In embodiments with multiple lines of weakness, spaced out along the blade’s surface, blade longevity may be further increased. For example, there could be ten lines of weakness, each one spaced behind the other and extending along the length of the blade. This provides eleven serrated cutting edges (including the original serrated cutting edge which is at the front of the blade before anything is snapped off) and therefore a blade which can last eleven times longer than a standard blade with the same characteristics, whilst still using only minimal extra material (the blade may be slightly wider than a standard blade to allow space for all the lines of weakness parallel to the length of the cutting edge in some cases, but nevertheless the total amount of material used is likely to be lower, e.g. less than twice as much material for a blade which lasts eleven times as long, noting that an attachment portion of a blade often contributes a significant portion of the total amount of blade material).

[0019] In some embodiments, each serrated cutting edge (both the originally exposed edge, and those edges provided by the lines of weakness on snapping) may be arranged to provide an at least substantially identical sizing, shaping, and optionally also spacing, of serrations. In some embodiments, all lines of weakness may be identical to each other. The original cutting edge may also be identical in shape of he cutting edge provided, or may differ.

[0020] In other embodiments with multiple lines of weakness, different serration design may be used for different lines of weakness. For example, a blade might comprise nine lines of weakness, divided into three sets of three. Each set of three may comprise three different serration designs, e.g. (i) one serrated edge suited for cutting dry wood, (ii) one serrated edge suited for green wood, and (iii) one serrated edge suited for plastics. A user may therefore snap off one or more blade portions to expose a blade with a desired cutting edge. This may improve utility, and avoid a user having to buy or carry multiple blades, e.g. for a DIY project. Size, spacing, and / or shape of the serrations may be constant along a line of weakness but different between lines of weakness in such embodiments.

[0021] In some embodiment, each serrated cutting edge (both the initial, original, cutting edge and those exposed by snapping the blade along a line of weakness) may take the form of an at least substantially straight line, with serrations therealong. The or each line of weakness may be at least substantially parallel to the exposed serrated cutting edge, and to any other line of weakness.

[0022] In other embodiments, each serrated cutting edge may take the form of a circle or arc of a circle, with serrations therealong. The curve of the or each line of weakness may be concentric with, and optionally locally parallel to, the curve of the exposed serrated cutting edge.

[0023] The or each line of weakness may be or comprise a gap in the material forming the blade at the point of each serration of the serrated cutting edge the line of weakness forms, the shape of the gap defining the shape of the cutting point of the serration. The gap may have an at least substantially constant width. Each gap may have at least substantially the same width. Optionally, the gap width may be between 0.05 mm and 0.40 mm, or from 0.1 mm to 0.3 mm, and optionally may be 0.2 mm.

[0024] The or each line of weakness may comprise:

[0025] (i) gaps in the material forming the blade in a region of a point of each serration; and

[0026] (ii) solid portions of the material forming the blade in a region of a trough between adjacent pairs of serrations.

[0027] In some embodiments, the gaps may extend around the whole serration and the solid portions may extend across the whole trough. In other embodiments, the gaps may extend around a peak or tip of a serration and the solid portion may extend out of the trough and onto a part of the serration. In other embodiments, the gaps may extend around the whole serration and along at least a part of the trough. The higher the proportion of the line of weakness made by the gaps, the easier the blade may be to snap. A minimum of 25% to 30% of the length of the line of weakness may be composed of solid portions.

[0028] The or each line of weakness may be or comprise a line of solid material with a thickness less than the thickness of the blade between the lines of weakness. Optionally the thickness of the material forming the line of weakness varies along the line of weakness, being thinnest in the region of serration cutting points and thickest in troughs between serration cutting points.

[0029] Gaps (i.e. regions of a thickness of zero) may be present in addition to regions of two or more different non-zero thicknesses along the or each line of weakness. In embodiments with gaps (i.e. regions of zero thickness along the line of weakness) the blade may have a thickness, T, between the lines of weakness, and the solid portions along the lines of weakness (between the points of the serrations / in the troughs) may be thinner than the thickness, T.

[0030] The or each line of weakness may be or comprise a row of perforations through the blade. Optionally the perforations are larger and / or more closely-spaced in the region of serration cutting points.

[0031] In embodiments with one or more gaps along the line of weakness, one of the gaps forming part of the line of weakness may extend to an edge of the blade at one end (or at each end) of the cutting edge, such that the gap forms an extreme point of the blade. This may help to ensure that the blade can snap, and cut, neatly right to its end.

[0032] In embodiments with one or more gaps along the line of weakness:

[0033] (i) at least one of the gaps may be substantially V-shaped, with the point of the V facing forwards; and / or

[0034] (ii) at least one of the gaps may be substantially W-shaped, with two points facing forward and one point facing backwards (or vice versa). Each trough along the line of weakness may take the form of a straight line parallel to the cutting edge between forward-facing serrations.

[0035] Each gap along the line of weakness may be a continuous gap extending between a pair of adjacent troughs and defining the shape of a forward-facing serration. The gap may have an at least substantially constant width.

[0036] Each gap may have a width along the blade’s surface (perpendicular to the general direction of the line of weakness) of at least 0.1 mm, and optionally of 0.1 mm to 0.5 mm.

[0037] The spacing between a forward-most point of the exposed serrated cutting edge and a forward-most point of the second serrated cutting edge may be at least 2 mm, optionally at least 3 mm or 4 mm, and optionally in the range from 4 mm to 6 mm.

[0038] The or each line of weakness may comprise solid material of the same thickness as the rest of the blade along at least 20%, 25%, 30%, or 35% of the length of the line of weakness.

[0039] The or each line of weakness may comprise solid material of the same thickness as the rest of the blade along at least 25%, 30%, 35%, 45% or 50% of the length of cutting edge, parallel to blade length. It will be appreciated that the serrations make the total length of the line of weakness greater than the total blade length.

[0040] A cutting point of a serration may be located at one extreme end of the serrated cutting edge. A cutting point of a serration may be located at each extreme end of the serrated cutting edge such that there is a forward-facing point at each lateral end of the blade. This may help to ensure that the blade can snap, and cut, neatly right to its end.

[0041] According to a fourth aspect, there is provided a tool comprising a blade as described in any preceding aspect.

[0042] The tool may be a (non-powered) hand tool. Additionally or alternatively, the tool may be a saw.

[0043] According to a fifth aspect, there is provided a blade-snapping tool for snapping off an exposed edge of a serrated blade as described in any of the first to third aspects, wherein the blade-snapping tool comprises a channel sized and shaped to receive the exposed serrated cutting edge and a front part of the blade extending therefrom, and having a depth corresponding to the spacing between the exposed serrated cutting edge and the (first) line of weakness therebehind such that only a first portion of the blade is received within the channel.

[0044] The channel depth may be at least 2 mm. The blade-snapping tool may be straight or curved, to match a blade with which it is intended to be used.

[0045] A tool may therefore be provided for snapping off a worn edge along the next / closest, or only, line of weakness. The tool comprises a body having a slit or channel therein for receiving a front edge of the blade - i.e. the cutting edge and a portion of the blade immediately behind the exposed cutting edge. In some cases, the tool may be long enough to receive the full length of the cutting edge. In other cases, the blade’s cutting edge may be longer than the tool such that only a portion of the cutting edge can be inserted into the tool at a given time.

[0046] The exposed cutting edge (or at least the forward-most points thereof) generally rests on the base of the channel in use.

[0047] The depth of the channel is preferably just less than the spacing between the exposed cutting edge and the adjacent line of weakness, the spacing being measured along the blade’s surface and generally at least locally perpendicular to the cutting edge / blade length.

[0048] For blades with multiple lines of weakness, the spacing between all adjacent pairs of lines of weakness is preferably at least substantially equal to the spacing between the first line of weakness and the original exposed cutting edge, such that the same tool can easily be used for each portion to be snapped off. The depth of the channel is therefore preferably just less than the spacing between lines of weakness.

[0049] The control of channel depth helps to ensure that the blade snaps only along the line of weakness closest to the front / closest to the exposed cutting edge so that serrated edges are not wasted by snapping off two or more blade portions at once.

[0050] According to a sixth aspect, there is provided a kit of parts comprising: a blade as described in any of the first to third aspects; and a blade-snapping tool as described in the fifth aspect, wherein the channel of the tool is sized and shaped to fit the blade.

[0051] According to a seventh aspect, there is provided a method of exposing a new cutting edge of a serrated blade for use, the method comprising: inserting a forwardmost portion of the blade according to any of the first to third aspects into the channel of a tool according to the fifth aspect such that at least a portion of the exposed cutting edge of the blade rests on a base of the channel; and moving the tool relative to the blade in a direction at least substantially perpendicular to the blade so as to snap off the portion of the blade between the exposed cutting edge and the line of weakness behind it.

[0052] According to a further aspect, there is provided a blade comprising an exposed serrated cutting edge and at least one line of weakness behind, and spaced from, the exposed serrated cutting edge, the line of weakness being shaped to provide a second serrated cutting edge when the blade is snapped along the line of weakness.

[0053] The blade may have any of the features as described with respect to the first, second, and / or third aspects. A blade-snapping tool according to the fifth aspect may be provided for the blade of this aspect.

[0054] According to a further aspect, there is provided a blade assembly for an oscillating tool, the blade assembly including: an attachment section having an attachment formation for mating with an oscillating tool; and a blade section, the blade section having a serrated front edge, in which at least one line of weakness is provided along the width of the blade section, behind the serrated front edge, each line of weakness defining at least one substantially forward-facing point.

[0055] The blade section may be made from carbide steel. The blade section may have any of the features as described with respect to the blade of the first, second, and / or third aspects.

[0056] Each line of weakness may be formed by a plurality of cut-outs. The cut-outs may be spaced apart along the width of the blade section, a front part of the blade section forward of the cut-outs being attached to a rear part of the blade section behind the cut-outs at least by material in the spaces laterally between the cut-outs. The cut-outs may be through cut-outs, whereby the blade section is cut all the way through the material. Alternatively, the cut-outs may be partial cut-outs, whereby the blade section is thinned.

[0057] One of the cut-outs may extend to a forward-facing point at a lateral edge of the blade section. Another cut-out may extend to a forward-facing point at the other lateral edge of the blade section.

[0058] At least one of the cut-outs may be substantially V-shaped, with the point of the V facing forwards.

[0059] At least one of the cut-outs may be substantially W-shaped, with two points facing forward and one point facing backwards.

[0060] The cut-outs may be bevelled. The serrations may therefore be bevelled.

[0061] A plurality of lines of cut-outs may be provided, the lines being spaced along the length of the blade section.

[0062] The blade assembly of the preceding aspect may be provided in combination with a tool for snapping-off a front part of the blade section, the tool comprising a body having a slit for receiving the front part of the blade section.

[0063] The skilled person would understand that features described with respect to one aspect of the invention may be applied, mutatis mutandis, to the other aspect of the invention. The unique serration design common to all aspects allows for the removal of sections of the blade to provide for a new, sharp, cutting edge, for example once the initially -exposed cutting edge becomes worn.

[0064] The serration technology described herein can be applied to any tool with a serrated cutting edge, such as multi-tools and saws, including the following: Jigsaw; Reciprocating Saw; Multi Tools / oscillating cutting tools (all shapes and sizes); Hack Saws (both hard and flexible blades); Hand / Cross Cut Saws (inc. Plain Tooth, M Tooth, Great American Tooth, Champion Tooth, Lance Tooth and Perforated Lance Tooth designs); Coping Saw; Bow Cut Saw; Fret Saw; Key Hole Saw; Japanese Saw; Panel / Back Saw; Pruning Saw; Veneer Saw; Wall Board / Plaster board / Gyprock Saw; Camping Saw; Bone Saw; Band Saw (inc. Standard Shape, Hooked Rip, Rounded Back, Skip Tooth, Raker or Regular, Wavy, Every Tooth (ETS), and Variable or Modified); Scroll Saw; and Tenon Saw.

[0065] It will be appreciated that each of the tool categories listed above has a variety of different blade shapes falling within the category, and that the snap-off serration design described herein can be applied to all of the known blade designs. Further, the snap off serration design described herein is not limited in its application to the tools on the above list.

[0066] There now follows, by way of example only, a detailed description of embodiments of the present invention with reference to the accompanying drawings in which:

[0067] Figure 1 shows a jigsaw blade with a “snap-off’ serration design;

[0068] Figure 2 shows a reciprocating saw blade with a “snap-off’ serration design;

[0069] Figure 3 shows a portion of the reciprocating saw blade of Figure 2, showing a close-up view of the cutting edge;

[0070] Figure 4 shows two different saw blades with similar “snap-off’ serration designs;

[0071] Figure 5 shows a tool which may be used to snap off a portion of the blade shown in any of Figures 1 to 4, so as to reveal a new cutting edge;

[0072] Figure 6 shows a round blade for an oscillating cutting tool;

[0073] Figure 7 shows a close-up view of a part of the blade of Figure 7;

[0074] Figure 8 shows two views of a tool which may be used to snap off a portion of the blade shown in Figures 6 and 7, so as to reveal a new cutting edge;

[0075] Figure 9 shows a close-up view of blade serration points / cutting points and interconnections;

[0076] Figure 10 is an illustration of variations in lines of weakness for the same general serration shape;

[0077] Figure 11 shows a straight-edged blade for an oscillating cutting tool; and

[0078] Figure 12 is a view of a snapped-off blade portion adjacent to the remaining blade of Figure 11.

[0079] In the Figures, like reference numerals are used for like or corresponding features.

[0080] Figure 1 shows a jigsaw blade 100; i.e. a blade arranged to form a part of a jigsaw. The blade 100 comprises an attachment section 111 arranged to be used to connect the blade to the rest of the jigsaw. The attachment section 111 comprises an attachment formation - e.g. one or more indentations, protrusions, apertures (e.g. screw holes or holes for a bolt to pass through) or the like - shaped and sized to fit with the rest of the tool so as to facilitate connection thereto. The attachment section 111 is an integral part of the blade 100 in the example shown, but may be permanently connected to the rest of the blade (e.g. by spot welds) or other ways of joining the sections known in the art in other examples.

[0081] The jigsaw may be a manual jigsaw (i.e. a hand tool) or a powered jigsaw.

[0082] The back of the blade 100 shown, i.e. the uppermost edge 110 in the orientation pictured in Figure 1, is smooth / flat, and not arranged to be used for cutting.

[0083] The front of the blade 100, i.e. the lowermost edge in the orientation pictured in Figure 1, is the cutting edge 101, and is serrated, having many teeth - or serrations - along the cutting edge 101. The cutting edge 101 extends in a straight line along a portion of the length of the blade 100, with equally shaped and sized teeth 101a evenly spaced along the cutting edge. Each tooth 101a is cut so that it curves towards the attachment section 111 in the example shown. It will be appreciated that the teeth 101a may be differently shaped, sized, and spaced (from the teeth shown, and / or from each other) in other examples, and that Figure 1 is provided by way of non-limiting example only.

[0084] Each tooth, or serration, 101a may be described as having a cutting point - i.e. the tip of the serration pointing outwardly from the blade 100; the forward-facing point of each serration 101a may be described as a cutting point - which engages a material to be cut in use. The blade 100 further comprises troughs between the teeth 101a; the troughs have flat bases parallel to the length of the blade in the example shown, but may alternatively be curved or indeed V-shaped.

[0085] In the example shown in Figure 1, the tooth pitch, P, is about 2 mm from tooth to tooth and the blade has around twelve teeth per inch (i.e. TPI =12). Commonly blades as described herein have around 12 to 24 TPI. The number of teeth per inch may vary depending on what materials the blade is intended to cut, amongst other variables, so this number is provided by way of non-limiting example only.

[0086] A jigsaw blade 100 such as that shown may have a blade thickness, T, of around 1.2 mm. Such a blade design may be selected to provide a coarse cut for timber. The total length of the blade 100, including the attachment portion 111, may be around 100 mm. Again, it will be appreciated that these details are provided by way of non-limiting example only. The snap-off blade design described herein can be applied to any number of TPI (teeth per inch) and different tooth pitches. Similarly, the serration edge can be optimised for timber, metals, plastics, composite materials or any desired material to be cut in different examples, and the shapes, sizings, and spacings of teeth may vary accordingly.

[0087] The blade 100 is made of a sheet of material, for example a steel such as a carbide steel. The material is selected to be hard and strong enough to cut whatever substrate the saw is intended to cut. The edges of the teeth 101a (and in particular the edges in the region of the cutting points) may be bevelled or otherwise sharpened to facilitate cutting.

[0088] The blade 100 further comprises a line of weakness 102. The line of weakness 102 extends along the blade, the full length of the exposed cutting edge 101 (and slightly beyond, in the example pictured). The line of weakness 102 is located behind the first, exposed, cutting edge 101, and spaced from the cutting edge 101, such that it is between the cutting edge 101 and the back of the blade 110. The line of weakness 102 is shaped to provide a second serrated cutting edge when the blade 100 is snapped along the line of weakness 102. The spacing between a forward-most point of the exposed serrated cutting edge 101 and a forward-most point of the line of weakness 102 may be at least 2 mm, 3 mm, or 4 mm, and optionally at least 5 mm or 6 mm. The spacing between a forward-most point of the exposed serrated cutting edge 101 and a forward-most point of the line of weakness 102 may be no more than 20 mm or 15 mm, and optionally no more than 10 mm. The spacing between a forward-most point of the exposed serrated cutting edge 101 and a forward-most point of the second serrated cutting edge 102 may be at least 2 mm, 3 mm, or 4 mm, and optionally at least 5 mm, 6 mm, 7 mm, or 8 mm. It will be appreciated that, as described in more detail below, the line of weakness 102 may have a non-negligible width (e.g. comprising gaps 102a in the blade material, the gap having a non-negligible width) such that the forward- most point of the second serrated cutting edge is slightly behind the forward-most point of the line of weakness 102.

[0089] The line of weakness 102 may be shaped to match the exposed cutting edge 101. In the example shown, the line of weakness 102 defines the shape of a set of teeth identical to those 101a of the exposed cutting edge 101, and aligned with them such that there is a tooth of the line of weakness 102 aligned with each tooth of the exposed cutting edge 101.

[0090] The blade 100 is designed to snap along the line of weakness 102 so as to remove a front portion 1 of the blade 100 and expose a new cutting edge 102 for use. The line of weakness 102 defines the shape of the new, second, cutting edge. The line of weakness 102 therefore extends to an edge of the blade 100 at each end of the line of weakness 102 so as to facilitate snapping off a complete portion of the blade 100.

[0091] The line of weakness 102 is weaker than the surrounding material of the blade 100 so as to allow the blade 100 to snap in a desired way, leaving behind a newly-exposed cutting edge of a desired shape. This may be achieved by weakening the blade material in a line along the blade 100 - e.g. by cutting it (e.g. laser-cutting it), thinning it, acid-etching it, or otherwise treating it, by removing some of the blade material in a line along the blade 100 whilst still leaving enough material to connect the front portion of the blade 100 to rearward portion(s) of the blade, and / or by manufacturing multiple individual blade portions of the desired shapes and connecting them together (e.g. using an adhesive or spot-welds) in such a way that the attachment is weaker than the bulk material so allowing snapping along the line of weakness (which may also be thought of as a line of attachment between blade portions).

[0092] In the example shown in Figure 1, the line of weakness 102 comprises a set of gaps, or cut-out portions, 102a, where the blade material has been removed and a set of connection portions 102b where material remains (“solid portions”), so connecting the front portion of the blade 100 to the rest of the blade. In the example shown, the gaps 102a are around the (forward-facing) teeth 101a, and the solid portions 102b are in the troughs between the teeth. As such, the tooth shape may be guaranteed even if detaching the front portion from the rest of the blade distorts the shape of the new, second, cutting edge in the region of the solid portions 102b.

[0093] The gaps 102a are at least substantially V-shaped in the example shown, with their forwardfacing points providing cutting edges for teeth 101a. The solid portions 102b are straight and parallel to the blade’s length in the example shown, and extend between rearward tips of adjacent V-shaped gaps 102a. The length of each solid portion 102b along the blade is approximately equal to the width of a tooth along the blade 100 in the example shown, such that the line of weakness 102 is solid for around 50% of the cutting edge’s length parallel to the blade - these solid portions provide sufficient rigidity for cutting, and sufficient strength for the front portion 1 not to become accidentally detached in use. The shape of the teeth means that the line of weakness 102 itself may be much less than 50% solid, as the outline of each tooth is longer than the tooth width or the gap between teeth - for example, the line of weakness 102 may be solid along at least 25%, 30%, 35% or 40% of the length of the line of weakness.

[0094] In some examples, the material of the solid portions 102b may be thinned to facilitate neat snapping along the intended line 102, whereas in other examples the solid portions may have the same thickness as the bulk blade material. The solid material of the line of weakness 102 has the same thickness as the rest of the blade in the example shown in Figure 1, although this may be varied, for example by etching shallow lines in the material of the solid portions, following the line of weakness, to facilitate a clean break when snapped.

[0095] The average thickness of material forming the blade along the line of weakness 102 is therefore lower than an average thickness, T, of the material forming the blade 100 adjacent to the line of weakness 102 / between the exposed cutting edge 101 and the line of weakness. In the example described above, the gaps 102a are effectively regions of the line of weakness with a thickness of zero. In other examples, the gaps 102a may be replaced with thinned portions of material (e.g. thinned by etching), which have a thickness greater than zero whilst still below the average blade thickness away from the line of weakness, T. The line of weakness 102 may be thinned along its full length in some examples, but thinned more at and around the forward-facing cutting points than it is between the cutting points, for example having thicknesses Ti, T2which may both be less than the average blade thickness, T, away from the line of weakness 102, with Ti being less than T2(0< TI<T2<T). The thickness at and around the cutting points is Ti; the material may be thinned to thickness Ti around the whole serration / tooth, with the material being thinned to the second thickness T2between the teeth - e.g. in a straight-line trough between adjacent serrations. In other examples, the material may be thinned to thickness Ti around the forward part of the tooth only - e.g. the forward-most 10%, 25 %, 50% or 75% of the tooth’s extent. The use of most thinning around the tip may help to ensure a neat and sharp cutting tip of the desired shape, minimising the risk of tooth distortion on snapping. In some examples, the troughs may be V-shaped or U-shaped instead of straight lines - the reduced thinning, T2, may be used at and in the region of these backward-facing tips - for example over the rear-most 10%, 25 %, 50% or 75% of the line of weakness’ extent. The thickness may vary smoothly between Ti and T2in some examples, instead of stepping sharply from one thickness to the other. More than two different thicknesses may be used along the line of weakness 102 in some examples, for example with an intermediate thickness, T3, extending along parts of the line of weakness 102 between the forward-facing tips (with thickness Ti) and the troughs (with thickness T2).

[0096] In alternative examples, the material of the line of weakness 102 may have the same thickness as the material of the rest of the blade 100, but may have a different structure or composition such that it is more brittle and snaps more easily. The line(s) of weakness 102 may be integrally formed when the blade 100 is formed in such examples.

[0097] In some embodiments with multiple lines of weakness 102, each line of weakness 102 is identical, and so takes the same force to break. In other such embodiments, the first line of weakness 102 may be the weakest, and so the first section 1 the easiest to break off, and the subsequent lines of weakness 103, etc. may be sequentially stronger, so making the subsequent sections 2, etc. harder to break off - this may reduce the risk of accidentally removing multiple sections at once. For example, the gaps 102a may be longer (e.g. extending across some of the trough as well as around the tooth, or extending around more of the tooth), and / or material more weakened, along lines of weakness closer to the exposed cutting edge. The change may be fractional, for example a 2-5% strengthening between consecutive lines of weakness 102.

[0098] Kerf is defined as the width of a cut or width of a material that is removed by a cutting process - for a flat blade as shown in Figures 1 and 2, the kerf size may be at least substantially equal to the width of the sheet of material forming the blade, i.e. to the blade thickness, T. However, it is known in the art that a selected tooth offset, or kerf size, can be applied to the selected serration design - for example by angling alternating teeth in different directions - to increase the kerf size in the cut material. This may be referred to as a kerf size of the blade. The size of the kerf determines the width of material that is removed, e.g. by a cutting or sawing process (which may be laser cutting, or any other suitable technique known in the art). Such a kerf design may be stamped into the blade for each line of weakness 102 when the blade is formed. It will be appreciated that having gaps 102a around the teeth (as opposed to weakened solid material) may facilitate obtaining a desired kerf design / tooth offset, but that in some embodiments solid material may still be present around the teeth, and may be (further) weakened by the stamping process, so facilitating later breaking along the line of weakness.

[0099] Returning to the example shown in Figure 1, at each end of the cutting edge (left and right sides in the orientation shown - these may be referred to as the lateral edges of the cutting edge), the line of weakness 102 extends onwards to the edge of the blade material. In particular at the end adjacent the attachment portion 111 in the example shown, this provides a longer cut-out or gap region 102a of the line of weakness 102 beyond the cutting edge.

[0100] In the example shown in Figure 1, the gaps 102a are formed by laser cutting. Other techniques known to the person skilled in the art may be used to create such gaps 102a instead of, or as well as, laser cutting, for example metal stamping. In the example shown in Figure 1, the gaps 102a have a non- negligible width, and are therefore shown as having two laser-cut edges 120a, 120b rather than as a single line. For example, the gap 102a may have a width of 0.1 to 0.5 mm, and optionally of around 0.3 mm. This gap width may provide some flexibility for the blade 100 without weakening it unduly, and / or may facilitate snapping off of the first blade portion 1 without distortion of the tooth shape.

[0101] More than one line of weakness 102 may be provided, and multiple blade portions 1 may be snapped off sequentially, one for each line of weakness 102. For example, a blade 100 may have 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 lines of weakness 102. The line of weakness closest to the exposed cutting edge 102 may be referred to as the first line of weakness 102. A maximum total depth of blade portions 1 to be removed may be set such that enough thickness of blade material is left between the final line of weakness and the back 110 of the blade 100 to provide a sufficient strength and rigidity for cutting.

[0102] Each blade portion 1 to be snapped off may have a depth, D, beyond the forward-most point of its rear edge, of at least 2 mm, 3 mm, or 4 mm, and optionally of at least 5 mm, 6 mm, 7 mm or 8 mm. The depth, D, is around 6 mm in the example shown. A minimum depth of each blade portion 1 may be set such that the blade portion is wide enough to provide a sufficient strength and rigidity for cutting and to avoid risk of the blade portion 1 snapping off in use. Figure 2 illustrates the application of a similar “snap-off’ serration design to a different saw blade 100a, with a different tooth shape. The description below focuses on the differences, as the common features can be understood by reference to the description of Figure 1. The example shown in Figure 2 is a reciprocating saw blade 100a which comprises a first, exposed, serrated cutting edge 101 and two lines of weakness 102, 103 therebehind, each defining a new serrated cutting edge which can be used after snapping off a portion 1, 2 of the blade 100. As in the example of Figure 1, the original cutting edge 101 and the lines of weakness 102, 103 are in the form of serrated straight lines, parallel to each other and spaced apart across the width of the blade 100.

[0103] The depth, D, of each blade portion 1, 2 is around 6-10 mm, and particularly around 8 mm, in the example shown. The total extent of each blade portion 1, 2 perpendicular to the blade’s length is greater than the depth, D, as it additionally includes the extent of the blade portion 1, 2 into the trough of the line of weakness 102, 103, behind the forward-most point of the next cutting edge.

[0104] The blade 100a shown in Figure 2 has a thickness, T, of around 0.9 mm, a length, L (including the attachment portion 111 and the length of the cutting edge), of around 150 mm and a width, W (from the back 110 to the front edge 101), of around 20 mm, and a TPI of around ten teeth per inch (governed by the pitch, P). The teeth 101a are symmetrical and straight-edged, instead of curved, in this example. The teeth 101a are again equally-spaced. It will be appreciated that tooth design can be adapted as desired for a given saw (or other bladed tool), and that the snap-off design as described herein can be adapted accordingly.

[0105] Unlike for the blade 100 shown in Figure 1, the blade 100a shown in Figure 2 does not have identical tooth separations on the original cutting edge 101 and the lines of weakness 102, 103 - instead, the teeth 101 of the lines of weakness 102, 103 are more widely spaced than those of the original cutting edge 101 (although each tooth has the same shape and almost the same size, the spacings between teeth are larger on the lines of weakness than on the initial cutting edge). This is depicted to illustrate the fact that it is not necessary for the serrated cutting edges 101, 102, 103 to be identical, even if they often are. Indeed, a deliberate choice may be made to have e.g. a zig-zag tooth pattern, without flat troughs, for the front edge 101, as the blade 100a is never snapped along the front edge 101 / no part of the blade is located forward of the front edge, so solid portions 102b are never needed on the front edge 101 - such a choice may facilitate manufacture.

[0106] The lines of weakness 102, 103 are formed by laser cutting, as for the line of weakness 102 of the blade 100 of Figure 1.

[0107] Figure 3 provides a close-up view of a portion of the first blade potion 1 of the blade 100a of Figure 2, showing seven forward-facing cutting points.

[0108] Figure 4 shows two different saw blades 100b, 100c with similar tooth designs. Again, the description below focuses on the differences for these blades as compared to the blades 100, 100a described above. The blade 100b shown on the left of Figure 4 is a Scorpion®-style saw blade, for a hand saw or similar, with a length, L, of around 240 mm including the attachment portion 111 or a length, LE, of around 210 mm without the attachment portion 111. The length LEmay correspond to the length of the cutting edge (straight-line length along the saw blade - i.e. not including additional line length due to the serrations). The attachment portion 111 includes an aperture I l la arranged to facilitate securing the blade 100b to a handle (not shown). It will be appreciated that the design of the attachment portion 111 may be adjusted as appropriate depending on the intended tool.

[0109] The blade 100c shown on the right of Figure 4 is shown as part of a panel saw (a hand tool), with the attachment portion mainly hidden within a handle 113, to which the blade 100c is secured.

[0110] Each blade 100b, 100c has an alternating pattern of longer and shorter teeth 101a along the cutting edge 101. The serrations 101 may therefore be thought of as W-shaped rather than V-shaped.

[0111] Each blade 100b, 100c is shown with a single line of weakness 102 behind the exposed cutting edge 101, although it will be appreciated that more lines of weakness may be provided in other examples. Again, the line of weakness 102 is spaced behind, and parallel to, the exposed cutting edge 101. The line of weakness 102 takes substantially the same shape as the exposed cutting edge 101, such that the second cutting edge, exposed once the front portion 1 of the blade 100b, 100c is snapped off, has the same shape as the first cutting edge 101 except in that the troughs between serrations are flattened for the lines of weakness. The cutting points therefore have the same shape and pattern, but the troughs between cutting points are flat rather than V-shaped.

[0112] As can be seen in the close-up view of the blade 100b, the longer teeth of the first cutting edge 101 are aligned with the shorter teeth of the second cutting edge in this example, and therefore offset from the longer teeth of the second cutting edge. In other examples, such as the blade 100c in which longer teeth are aligned with longer teeth, the alignment may differ.

[0113] The teeth 101 of the second blade 100c shown in Figure 4 are very similar to those of the first blade 100b shown in Figure 4 (and only one close-up is shown for ease), but it is noted that the orientation of the teeth is reversed - whereas the Scorpion® blade 100b has alternating longer and shorter teeth 101 pointing forward (downwards in the orientation shown), such that the cutting point / peak of one tooth 101 is not at the same level as the cutting points / peaks of the teeth on either side of it, the panel saw blade 100c has the “W”s the other way up such that all of the cutting points / peaks of the teeth are on the same level but the troughs between them alternate in depth. Different tooth designs are better-suited to different materials to be cut and intended sawing angles, so a blade can be designed accordingly.

[0114] As for the blades 100, 100a described above, the first cutting edge 101 of the blades 100b, 100c of Figure 4 has angled peaks and troughs, whereas the line of weakness 102 has blunted / flattened troughs 102b between the angled peaks 102a to provide a connection to the blade material behind it. Cuts, in this case laser cuts 120a, 120b, are again used to create gaps around the forward-facing teeth 101, the gaps being separated by portions of solid material in the troughs 102b.

[0115] The blades 100, 100a, 100b, 100c described above are all at least substantially straight (i.e. the cutting edge is a straight line overall). At least substantially the same design of blade-snapping tool 150, as shown in Figure 5, can therefore be used to snap off the desired portion 1, 2 of the blade 100.

[0116] The tool 150 comprises a block 150 with a channel 152 running along its length, Lc. The channel 152 runs along the full length of the block 150 in the example shown, being open at the ends such that a blade 100, or a portion of a blade 100, can be slid into it from either end. The channel 152 may also be referred to as a slit or groove. The channel 152 may be closed at one end and open at the other end in some examples.

[0117] The channel 152 has a depth, De, selected to correspond to a blade depth, D, which is defined as the depth of a blade portion 1, 2 between the forward-most point of its rear edge and the forward-most point of its front edge. The channel depth, De, may be selected to be equal to, or slightly less than, the blade depth, D, such that only the forwardmost blade portion 1 (or blade portion 2, once blade portion 1 has been removed) can lie within the channel 152, to be snapped off

[0118] In the example shown, the channel depth, De, is between 2 mm and 10 mm, more specifically between 4 mm and 10 mm, and more specifically is 6 mm. The channel 152 is selected to have a width slightly wider than the blade thickness, T, (e.g. 0.5 mm or 1 mm wider) such that the blade 100 can be slid into the channel 152 easily, but does not have much lateral movement within the channel.

[0119] Inserting the blade 100 into the channel 152 and then twisting / bending the blade whilst the forwardmost blade portion 1 is trapped within the channel allows the forwardmost blade portion 1 to be snapped off neatly, and by hand, without a user having to grip the serrated edge 101.

[0120] In the example shown, the length, Lc, of the block 150, and therefore of the channel 152, is around 50 mm. Blade length, L, and more specifically the length of the edge of the blade used for cutting, LE, is generally greater than 50 mm - the tool 150 may be applied to one portion of the blade’s length and then moved along, with consecutive snapping actions for different parts of the blade 100 (depending on blade rigidity). In some examples, the tool 150 may be placed centrally with respect to the cutting edge and a single snapping action may be sufficient to detach the front blade portion 1 even if the tool 150 is shorter than the cutting edge. In other examples, e.g. for a shorter blade 100 or longer tool 150, the whole of the cutting edge’s length may fit within the tool 150 at once. In such cases, the slit 152 may have closed ends rather than open ends.

[0121] In the example shown, the height, He, of the block 150 is between 6 mm and 20 mm, and more specifically around 8 mm. It will be appreciated that the dimensions of the block 150 may be selected as desired for ease of handling and portability - only channel dimensions are set based on the blade 100, and the blade-snapping tool 150 as a whole may take any desired shape (it does not need to be a cuboid, for example). In some examples, the blade-snapping tool 150 may be provided as part of a packing case for the blade 100 or a packing case for a cutting tool comprising the blade 100 - for example, a hard plastic toolbox may have a labelled channel in its lid or side for use in snapping the blade 100.

[0122] The tool 150 is designed to aid in the clean separation of segments 1, 2 of the blade 100. The channel depth, De, is carefully selected to ensure only the forward-most snap-off section 1 is removed. Each tool 150, and in particular the channel 152 of each tool, is therefore designed with the parameters of the blade 100 with which it is to be used in mind - the channel 152 is sized and shaped to accommodate the blade 100 at the correct depth. This depth is at least substantially equal to the distance between separations (i.e. between lines of weakness 102, 103, or between the exposed cutting edge 101 and the first line of weakness 102 behind that exposed cutting edge). That depth is around or equal to 6 mm in various examples described herein, but can be varied as appropriate for different blades.

[0123] Figure 6 shows a round oscillating blade lOOd for a multi-tool or similar, in conjunction with a snapping tool 150a suited to the round blade lOOd. The attachment portion 111 is located centrally with respect to the blade lOOd, and takes the form of a universal connection point 111 as is known for multitool blades.

[0124] The exposed cutting edge 101 extends around a circumference of the blade lOOd - forming an arc of a circle of around 270°, with a gap for attachment to a tool. Two lines of weakness 102, 103 are located behind the exposed cutting edge 101, and spaced from it. The first line of weakness 102 is spaced from the exposed cutting edge 101 by a distance of around 6 mm. The second line of weakness 103 is spaced from the first line of weakness 102 by a distance of around 6 mm. Each blade portion 1, 2 therefore has a depth, D, of around 6 mm. The first and second lines of weakness 102, 103 therefore form arcs of circles with radii less than the radius, R, of the exposed cutting edge 101 by 6 mm and 12 mm respectively. The arcs are all arcs of concentric circles.

[0125] The teeth 101a, 102a, 103a of the exposed cutting edge 101 and the lines of weakness 102, 103 are angularly aligned in the example shown (their peaks lie along the same radial line). As for the examples discussed above, the troughs 102b are flattened for the lines of weakness 102, 103 for ease of connection of the material in front of the line of weakness to the material behind, but the original cutting edge 101 may have sharp peaks and troughs.

[0126] Other than the shape of the blade lOOd, and in particular the curvature of the cutting edge, the features and options correspond to those of the blades 100-lOOc described above and that description is not repeated here.

[0127] Figure 7 shows a close-up view of a portion of the blade lOOd. A “snap-off point” or connection point of solid material 102b is provided in each trough of the line of weakness 102, between every pair of teeth 102a.

[0128] It will be appreciated that this design can be applied for any pitch, P, of the teeth - i.e. for any number of teeth per inch. However, for relatively large gaps between teeth, weakening or thinning of the solid material in the connection portions 102b may be desired to facilitate snapping. Similarly, for relatively large teeth, the use of thinned material, or of multiple smaller perforations instead of large gaps fully surrounding each tooth 102a, 103a, may be desirable to increase overall blade strength or rigidity. In some examples, lines of weakness may comprise multiple different blade weakening techniques - for example, shaped gaps around serration points and rows of perforations (i.e. smaller, and optionally circular, gaps or holes through the blade material) along troughs between serration points.

[0129] Two lines of weakness 102, 103 are shown in Figure 7; it will be appreciated that more or fewer lines of weakness 102, 103 may be provided in other examples, limited only by blade size and required strength.

[0130] The tool 150a has a curved shape so as to be suitable for use with a curved blade lOOd. The tool 150a can be slid onto and around the edge of the blade lOOd / the blade lOOd may be slid into and along a channel 152a of the tool 150. The channel 152a is open-ended to allow this insertion and relative movement. Again, the depth, De, of the channel 152a is selected to correspond to the depth of a portion 1 of the blade lOOd designed to be snapped off, and the thickness, Tc, of the channel 152a is selected to be equal to or slightly larger than the blade thickness.

[0131] The other dimensions of the tool 150a, e.g. He, may be selected as desired for aesthetics and ease of use, provided access to the channel 152a is not blocked.

[0132] Figure 8 shows top and perspective views of the curved tool 150a. The tool 150a takes the general form of an arc of a circle, the arc being subtended by an angle of around 90° in the example shown - shorter or longer arcs may be provided in other examples. A straight-line distance, A, between ends of the tool 150a, and more specifically of the channel 152a, may be around 60 mm.

[0133] The curved tool 150a has a substantially constant thickness, except in the region of the upper / outer part of the channel 152a, where an angled corner or chamfer is provided at each outer corner of the tool. This may allow a more comfortable grip of the tool 150a near the line of weakness of the blade to be snapped in use.

[0134] As described above for the other tool 150, a single snapping motion with the tool 150a may be sufficient to detach a blade portion 1, or the tool 150a may be repeatedly applied to the blade lOOd in different positions with multiple snapping motions being used to fully detach the blade portion 1. The radius, R, of the tool 150a is selected to be appropriate for the radius of the blade lOOd. In particular, the radius of the channel 152a at its base may match the blade’s radius exactly for the maximum blade size / before any portions 1, 2 have been removed. It will be appreciated that the blade’s radius will decrease as portions are removed so the fit may be poorer for subsequent portions 2. For generally round blades lOOd with a large number of removable portions 1, 2, 3, ... , an adjustable tool 150a, or multiple tools 150a of different sizes, may be provided.

[0135] In the example shown in Figure 8, the channel depth is around 6 mm, to match the spacing between cutting edges 101 and lines of weakness 102, 103. This may be adjusted as appropriate depending on depth, D, of the blade portions 1, 2.

[0136] A channel thickness, Tc, of around 1.4 mm may be selected. This may be adjusted as appropriate depending on the thickness of the blade 100, to slidingly receive the blade without much freedom in lateral movement (e.g. being only 0. 1-1.0 mm wider than the blade thickness, T).

[0137] Tool height, He, may be selected as desired for comfort of use / utility. It will be appreciated that the overall shape and size of the tool 150a may vary significantly, provided that access to the channel 152a is allowed for.

[0138] Figure 9 provides a close-up view of an exposed (first) cutting edge 101 of a straight blade 100 and a first line of weakness 102 behind it, which provides a second cutting edge once the first blade portion 1 is removed.

[0139] In the example shown, the serration height, SH, of the second cutting edge 102 is slightly lower than that for the first cutting edge 101 due to the space taken by the gap between cuts around the serration. The serration height, SH, of the first cutting edge 101 is around 2.5 mm in the example shown, and that of the second cutting edge 102 may be around 2.3 mm, by way of example - the gap having a width of around 0.2 mm. The pitch, P, is around 2.5 mm from serration peak to serration peak for the first cutting edge 101 in the example shown, and around 3.5 mm for the first line of weakness 102. The wider pitch of the line of weakness may allow more space for a trough 102b in which the first blade portion 1 is joined to the second blade portion 2 whilst providing serrations of a similar size and shape to the first, exposed, cutting edge.

[0140] The line of weakness 102 comprises gaps 102a around the serration peaks, and solid material portions 102b in the troughs between serrations. The line of weakness 102 comprises straight line portions parallel to the length of the blade 100 between the forward-directed serrations. Each straight- line portion / trough has a trough width, Tw, of around 2 mm in the example shown, leaving 0.75 mm each side of the trough 102b for an angled slope of the serration.

[0141] These comparisons between the first cutting edge 101 and lines of weakness 102 are provided by way of non-limiting examples only, and it will be appreciated that serration height, angle, and spacing, P, may all be chosen as desired individually for each of the (exposed and exposable) cutting edges 101, 102, 103. Figure 10 illustrates three different ways in which serrations may be cut for a blade 100. For example, where an exposed cutting edge 101 has a zig-zag pattern of serrations of height SH, with no flat troughs between them, and it is desired to provide lines of weakness 102, 103 with the same serration peak spacing and angle, but with flat troughs 102b between them to connect blade portions 1, 2, a choice can be made as to where to place the trough 102b. The sections of the blade in these “troughs” 102b remain uncut to maintain blade integrity, whilst other sections 102a of the blade material along the line of weakness 102, 103 are removed completely in various examples (or thinned in others). The longer the troughs 102b, the stronger the blade, and the harder it is to snap off a blade portion. The shorter the troughs 102b, the weaker the blade, and the easier it is to snap off a blade portion. In various embodiments, the troughs may have a maximum length of 6 mm, and optionally of 4 mm or 3 mm. A height, Hi, H2, H3, at which to set the trough 102b must therefore be selected to provide sufficient strength for the blade to perform its function, whilst also allowing for an efficient and clean break along the line of weakness 102. It will be appreciated that this balance will depend on the intended material to be cut, the blade thickness, and the blade material (often a carbide steel).

[0142] For a given blade 100 with gaps around the serration peaks, the strength of the blade 100 and the ease at which it can be snapped off are determined by the amount of material left between each serration of the blade. In Figure 10, A, B, and C represent the distances between the tip of the serration and the troughs 102b, which form the snap-off points of the line of weakness 102. The further down the “valley” between serrations the uncut part is (i.e. the larger the distance A, B, C), the easier it is to snap off the blade portion 1, as the solid connecting portions of the line of weakness 102 are shorter - there is less connecting material.

[0143] In summary, between each pair of forward-facing tips of the serrations, there is a valley and at the bottom of each valley there is a connection point between the forward-most blade section 1 and the section 2 behind it. The lower into the valley the connection point is, the easier it is to snap the blade section 1 off as there is less material holding the sections 1,2 together.

[0144] In some examples, this depth A, B, C may be varied between lines of weakness, for example so as to make the first sections 1 of a blade 100 easier to snap off than the later sections. This may reduce the risk of snapping off more than one section 1, 2 at a time.

[0145] Figure 11 shows a blade lOOe for a multi-tool which has a straight cutting edge, unlike the round cutting edge of the blade lOOd shown in Figure 6. A similar attachment portion 111 to that shown in Figure 6 may be provided, as it will be appreciated that straight and rounded cutting blades may be used with the same oscillating cutter. The below discussion focuses on the difference from blades 101 - 10 Id described above to avoid repetition.

[0146] In this example, the cutting edge extends across the full length, L, of the blade lOOe (here, the blade length, L, is defined parallel to the cutting edge for consistency with the blades 100-lOOc described above; however it will be appreciated that, given the overall dimensions on the blade lOOe shown in Figure 11, this dimension may be more normally referred to as blade width, with the longer extent of the blade from its front to its back being described as its length).

[0147] The blade lOOe, like most known multi-tool blades, has an attachment section 111 which is formed separately from the rest of the blade. The attachment section 111 is permanently joined to the rest of the blade by spot welds I l la indicated schematically in Figure 11. Other ways of joining the sections are possible, and in some examples the attachment section 111 and the rest of the blade may be made from a single continuous piece of material (e.g. carbide steel) instead.

[0148] The blade lOOe of Figure 11 has eight lines of weakness 102-109 behind the exposed cutting edge 101, so providing a total of nine cutting edges 101-109 which may be used consecutively, snapping off one blade portion 1-8 at a time, when the currently -exposed cutting edge is worn down, damaged, or otherwise no longer wanted. The lines of weakness 102-109 are identical to each other in the example shown, such that each cutting edge 102-109 they provide is substantially identical. The pitch is slightly smaller for the first, exposed, cutting edge 101 shown, as troughs 102b to act as connecting portions are not needed for that first edge. All cutting edges 101-109 may be identical in other examples, or there may be different variations between cutting edges 101-109.

[0149] By providing a tool 150 having a slit 150a which is slightly less than the spacing, D, between lines 101-109, the front part of the blade section 1 can be reliably snapped off along the first line of weakness 102, and each subsequent blade section 2-8 can correspondingly be snapped off along the next line of weakness 103-109 at each stage. In this example, this can be done eight times to reveal a new, sharp, serrated, edge each time, before the blade lOOe is finally completely worn out and has to be discarded.

[0150] In the example shown, the cutting edge 101-109 finishes at a cutting peak of a serration (rather than in a trough, or part way up a serration) at either side of the blade lOOe - this may help to provide neat cutting right to an edge of the blade lOOe. At each extreme lateral edge of the blade lOOe, on each line of weakness, a gap 102a extends all the way to the edge of the blade material to form a point 101a, 102a, 103a at each edge of the blade lOOe. This means that when the front part 1 is removed to reveal a new serrated edge 102-109, the new serrated edge is also able to cut all the way along its length. This can be important for fine-detailed cutting work for which oscillating tools are often used.

[0151] Figure 12 provides a close-up view of a portion of the blade of Figure 11, with the second blade section 2 shown separated from the remainder of the blade lOOe. The arrows between the second and third blade sections 2, 3 illustrate how the sections of the blade fit together. The first blade section 1 is not shown - in effect, it has already been removed.

[0152] Note that the spaces / valleys 102b between the serrations, i.e. parts which in Figure 11 were joined together with continuous material connecting the front 2 and rear 3 parts, in front of and behind the line of weakness 103, have snapped so that the front blade section 2 is detached from the remainder of the blade lOOe. In some examples, the troughs 102b may comprise a line of perforations, or a shallow etched line into the material, to facilitate neat snapping along the line of weakness 102-109. In other examples, the material in the troughs 102b may be identical to blade material within a blade section 1-8, and the line of weakness across the trough 102b may be defined only by the weakened points at the end and start of the serrations 102a sandwiching the trough 102b. These serrations 102a are defined by gaps - continuous regions of cut-away material outlining the serration peak - in the examples shown, but the material may be differently weakened so as to define the serrations in other examples, for example by thinning the material (e.g. by etching) or by providing a row of discrete perforations instead of a continuous gap. For example, closely-spaced perforations may be provided around the teeth and more widely-spaced perforations may be provided in the troughs between teeth. Any of the above blades lOO-lOOe may be provided together with an appropriately-shaped bladesnapping tool 150, 150a as a kit of parts.

[0153] A method of exposing a new cutting edge of a serrated blade 100-lOOe for use may be performed using that kit of parts, by: inserting a forwardmost portion of the blade 100-lOOe into the channel 152, 152a of a blade-snapping tool 150, 150a such that at least a portion of the exposed cutting edge 101 of the blade rests on a base of the channel; and moving the blade-snapping tool 150, 150a relative to the blade 100-lOOe in a direction at least substantially perpendicular to the plane of the blade so as to snap off the portion 1 of the blade between the exposed cutting edge 101 and the line of weakness 102 behind it.

[0154] For a straight blade-snapping tool, the blade-snapping tool 150 may be rotated around an axis parallel to the length of the channel 152, 152a (which would also be parallel to the cutting edge) to snap off the blade portion 1, or the blade-snapping tool 150 could be moved laterally relative to the blade.

[0155] Similarly, for a curved blade-snapping tool, the blade-snapping tool 150a may be rotated around an axis tangential to the curve of the channel 152a (so locally parallel to the channel where the tangent touches the channel’s curve), or the blade-snapping tool 150 could be moved laterally relative to the blade, to snap off the blade portion 1.

[0156] Any of these combinations can be defined as providing relative movement of the blade-snapping tool 150, 150a and blade 100-lOOe perpendicular to the plane of the blade.

[0157] The relative movement may be created by moving the blade whilst the blade-snapping tool 150, 150a is held still. Equivalently, the blade-snapping tool 150, 150a may be moved whilst the blade 100 is held still, or both may be moved.

[0158] A cutting tool comprising any of the above blades 100-lOOe may be provided - the blade 100- lOOe may be separably attached to the cutting tool, or may be permanently attached to the cutting tool (e.g. by welding). The cutting tool may be a hand tool or a power tool such as a multi-tool. The cutting tool may be a saw.

[0159] The specific blades and tools described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

CLAIMS1. A tool blade comprising an exposed serrated cutting edge and a first line of weakness behind the exposed serrated cutting edge and spaced from the exposed serrated cutting edge, the line of weakness being shaped to provide a second serrated cutting edge when the blade is snapped along the line of weakness, and wherein the spacing between a forward-most point of the exposed serrated cutting edge and a forward-most point of the second serrated cutting edge is at least 2 mm.

2. The tool blade of Claim 1, wherein the tool blade is at least one of:(i) a saw blade; and(ii) a hand-tool blade.

3. A saw blade comprising an exposed serrated cutting edge and at least one line of weakness behind, and spaced from, the exposed serrated cutting edge, the line of weakness being shaped to provide a second serrated cutting edge when the blade is snapped along the line of weakness.

4. The tool blade of any preceding claim, wherein the line of weakness is weaker at and around the forward-facing cutting point of each serration, and stronger in troughs between adjacent serrations, and wherein optionally an average thickness of material forming the blade along the or each line of weakness is lower than an average thickness of the material forming the blade adjacent to the or each line of weakness.

5. The tool blade of any preceding claim, further comprising additional lines of weakness behind the first line of weakness, each additional line of weakness being shaped to provide a further serrated cutting edge when the blade is snapped along the line of weakness.

6. The tool blade of any preceding claim, wherein:(i) each serrated cutting edge takes the form of an at least substantially straight line, with serrations therealong, and the or each line of weakness is at least substantially parallel to the exposed serrated cutting edge; or(ii) each serrated cutting edge takes the form of a circle or arc of a circle, with serrations therealong, and the curve of the or each line of weakness is concentric with the curve of the exposed serrated cutting edge.

7. The tool blade of any preceding claim, wherein the or each line of weakness comprises:(i) gaps in the material forming the blade in a region of a point of each serration; and(ii) solid portions of the material forming the blade in a region of a trough between adjacent pairs of serrations.

8. The tool blade of any preceding claim, wherein the or each line of weakness is or comprises a line of solid material with a thickness less than the thickness of the blade between the lines of weakness, andwherein optionally the thickness of the material forming the line of weakness varies along the line of weakness, being thinnest in the region of serration cutting points and thickest in troughs between serration cutting points.

9. The tool blade of any preceding claim, wherein the or each line of weakness is or comprises a row of perforations through the blade, and wherein optionally the perforations are larger and / or more closely- spaced in the region of serration cutting points.

10. The tool blade of any preceding claim, wherein the or each line of weakness is or comprises a gap in the material forming the blade at the point of each serration of the serrated cutting edge the line of weakness forms, the shape of the gap defining the shape of the cutting point of the serration.

11. The tool blade of Claim 7 wherein the blade has a thickness, T, between the lines of weakness, and wherein the solid portions along the lines of weakness between the points of the serrations are thinner than the thickness, T.

12. The tool blade of Claim 7 or any claim dependent thereon wherein at least one of the following applies:(i) one of the gaps forming part of the line of weakness extends to an edge of the blade at one end of the cutting edge, such that the gap forms an extreme point of the blade; and(ii) each gap has an at least substantially constant width, the width of all gaps optionally being the same, and wherein optionally the gap width is ion the range from 0.1 mm to 0.3 mm.

13. The tool blade of Claim 7 or any claim dependent thereon, wherein:(i) at least one of the gaps is substantially V-shaped, with the point of the V facing forwards; and / or(ii) at least one of the gaps is substantially W-shaped, with two points facing forward and one point facing backwards.

14. The tool blade of Claim 7 or any claim dependent thereon, wherein each trough takes the form of a straight line parallel to the cutting edge between forward-facing serrations.

15. The tool blade of Claim 7 or any claim dependent thereon, wherein each gap is a continuous gap extending between a pair of adjacent troughs and defining the shape of a forward-facing serration, the gap optionally having an at least substantially constant width.

16. The tool blade of any preceding claim, wherein the spacing between a forward-most point of the exposed serrated cutting edge and a forward-most point of the second serrated cutting edge is in the range from 4 mm to 6 mm.

17. The tool blade of Claim 7 or any claim dependent thereon, wherein each gap has a width along the blade’s surface of at least 0.1 mm, and optionally of 0.1 mm to 0.5 mm.

18. The tool blade of any preceding claim, wherein the or each line of weakness comprises solid material of the same thickness as the rest of the blade along at least 25%, 30%, or 35% of the length of the line of weakness.

19. The tool blade of any preceding claim, wherein the or each line of weakness comprises solid material of the same thickness as the rest of the blade along at least 30%, 45% or 50% of the length of cutting edge, parallel to blade length.

20. The tool blade of any preceding claim, wherein a cutting point of a serration is located at one extreme end of the serrated cutting edge, and optionally wherein a cutting point of a serration is located at each extreme end of the serrated cutting edge such that there is a forward-facing point at each lateral end of the blade.

21. A tool comprising a blade as described in any preceding claim.

22. The tool of Claim 21, wherein the tool is at least one of a hand tool, and a saw.

23. A blade-snapping tool for snapping off an exposed edge of a serrated blade as described in any of Claims 1 to 20, wherein the blade-snapping tool comprises a channel sized and shaped to receive the exposed serrated cutting edge and a front part of the blade extending therefrom, and having a depth corresponding to the spacing between the exposed serrated cutting edge and the first line of weakness therebehind such that only a first portion of the blade is received within the channel, the channel depth being at least 2 mm.

24. A kit of parts comprising: a blade as described in any of Claims 1 to 20; and a tool as described in Claim 23, wherein the channel of the tool is sized and shaped to fit the blade.

25. A method of exposing a new cutting edge of a serrated blade for use, the method comprising: inserting a forwardmost portion of the blade according to any of Claims 1 to 20 into the channel of a tool according to Claim 23 such that at least a portion of the exposed cutting edge of the blade rests on a base of the channel; and moving the tool relative to the blade in a direction perpendicular to the blade so as to snap off the portion of the blade between the exposed cutting edge and the line of weakness behind it.

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