GB2431614A

GB2431614A - Saw blade with releasably fastened cutting portion

Info

Publication number: GB2431614A
Application number: GB0615611A
Authority: GB
Inventors: Robert Jackson
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-10-26
Filing date: 2006-08-07
Publication date: 2007-05-02
Also published as: GB0615611D0

Abstract

A saw blade 12 has an elongate cutting portion 18, a separately formed elongate support portion 20 for supporting the cutting portion, and means 22 for releasably fastening the cutting portion and the support portion together, such that the cutting portion and fastening means lie within the kerf K of the blade. Preferably the fastening means comprises a plurality of releasable fastening elements 32, such as circlips, that engage in complementary holes 34, 36 in rabbeted portions 28, 30 of the cutting portion and support portion. A method of realeasably laminating a laminar element 18 to a member 20 comprises the steps of forming tapered holes 32, 36 through the laminar element and member, and assembling the laminar element and member by inserting a fastening element 32 into the holes, the fastening element having a groove 38 that receives the tapered holes, and where the fastening element does not protrude significantly from a face of the laminar element.

Description

TITLE

Saws, saw blades and laminating laminar elements

DESCRIPTION

A first aspect of this invention relates to saws and saw blades. The invention was originally conceived in connection with hand saws having a relatively wide blade with or without a back, such as rip saws, cross-cut saws, panel saws, flooring saws, tenon saw, dovetail saws and gems saws. However, this aspect of the invention may have application to other types of saw.

Such hand saws, if of the highest quality, if looked after well and if sharpened as required, can last a lifetime. However, high quality saws are expensive. Sharpening saws is tedious. Sharpening saws of low quality, or sharpening saws incorrectly, can soon lead to loss of tooth form. Using a saw heavily, especially if it has lost its set, can result in a permanent buckle in the blade, which makes subsequent use of the saw difficult. Because of these problems, there is a tendency amongst some to use a hacksaw, when, for example, a rip, cross-cut or tenon saw would be more appropriate for the job. Although a typical hacksaw is inexpensive and uses inexpensive replaceable blades, it does have a disadvantage compared with, say, a rip, cross-cut or tenon saw that it is more difficult to cut in a straight line. Also, a conventional hacksaw has a disadvantage compared with a rip, cross-cut or panel saw, that the depth of cut possible is limited by the spacing between the cutting edge and the spine of the hacksaw frame.

The first aspect of the present invention, or at least specific embodiments of it, aims to provide an improved blade for a hand saw.

In accordance with the first aspect of the present invention, there is provided a saw blade having an elongate cutting portion with a series of cutting teeth and an elongate support portion for supporting the cutting portion, the cutting portion and support portion being separately formed, and the saw blade further including means for releasably fastening the cutting portion and the support portion together such that the cutting portion and fastening means lie within the kerf of the blade. The saw blade therefore has the advantages that: * If the teeth become blunt or lose their set, the cutting portion can be discarded and replaced without the need to replace the support portion (and any handle that may be attached to it).

* The cutting portion and the support portion may be made of different materials, or differently treated materials, so as to optixnise their individual cutting and supporting functions.

* The cutting portion may be replaced with a different cutting portion having different characteristics (for example of different material, or with a different pitch, form, rake angle, fleam angle andlor set of the teeth) without the need to replace the whole blade.

* The saw blade in combination with a number of cutting portions takes up less storage space than the same number of conventional saw blades.

The first aspect of the invention is not only applicable to a blade in which the support portion lies within the kerf of the blade (corresponding to a conventional cross-cut, rip or panel saw), but also to a blade in which the support portion has a panel fastened to the cutting portion and a reinforcing back spaced from the cutting portion, and the panel lies within the ken of the blade (corresponding to a conventional back saw).

Preferably, the cutting portion has a rabbeted portion that engages with a is complementary rabbeted portion of the support portion to form a half-lapped joint. In this case, the fastening means preferably comprises a plurality of fastening arrangements spaced apart along the length of the joint, each fastening arrangement including a releasable fastening element that engages in complementary holes in the rabbeted portions. Each hole in each rabbeted portion preferably has at least a portion that tapers or is shouldered towards the respective complementary hole, and each fastening element preferably has a groove that receives the tapering or shouldered portions of the respective holes. In one embodiment, each hole is round, and each fastening element is provided by a grooved internal circlip that can be contracted to remove the circlip from and replace it in the respective holes. In another embodiment, each hole is a slot having a pair of generally parallel sides that taper or are shouldered in part towards the complementary slot, and each fastening element has the form of a strip with grooved edges to engage the tapering or shouldered sides of the slots so that the strip can be slid out of and into the slots.

A second aspect of the present invention relates to a method (which may be used with the saw blade of the first aspect of the invention or in any other application) of releasably laminating a laminar element (such as the cutting portion of the saw blade or any other laminar element) having first and second faces to a member (such as the support portion of the saw blade or any other member). A third aspect of the invention relates to an assembly of a member and a laminar element having first and second faces releasably laminated to the member.

It is known to laminate a laminar element to another member (such as another laminar element) using an adhesive, rivets or by spot welding. However, it is then difficult subsequently to separate the elements. It is also known to use releasable fasteners, for example a bolt passing through holes in the elements and engaging a nut, or a screw passing through a hole in one of the elements and engaging a tapped hole in the other element. In the first case, at least the nut will protrude from the surface of the laminar element. In the second case, if the laminar element having the tapped hole is thin, weakness of the threads of the tapped hole becomes an issue.

The method of the second aspect of the invention comprises the steps of: forming a first hole through the laminar element, the first hole having at least a portion that is tapered or shouldered towards the first face of the laminar element; forming a complementary second hole in a surface of the member, the second hole having at least a portion that is tapered or shouldered towards said surface of the member; assembling the laminar element and the member with the first face of the laminar element facing the surface of the member and with the holes aligned; and inserting a fastening element into the holes, the fastening element having a groove that receives the tapering or shouldered portions of the holes such that the fastening element fastens the laminar element to the member and such that the fastening element does not protrude significantly from the second face of the laminar element.

In the assembly of the third aspect of the invention: a first hole is formed through the laminar element, the first hole having at least a portion that is tapered or shouldered towards the first face of the laminar element; a complementary second hole is formed in a surface of the member, the second hole having at least a portion that is tapered or shouldered towards said surface of the member; the laminar element and the member is assembled with the first face of the laminar element facing the surface of the member and with the holes aligned; and a fastening element is disposed in the holes, the fastening element having a groove that receives the tapering or shouldered portions of the holes such that the fastening element fastens the laminar element to the member and such that the fastening element does not protrude significantly from the second face of the laminar element.

In either the second or third aspect of the invention, the member may be a second laminar element having a second face opposite said surface, and in this case the fastening element, once inserted, preferably does not protrude significantly from the second face of the second laminar element. In one embodiment, each hole is round, and the fastening element is provided by a grooved internal circlip that can be contracted to remove the circlip from and replace it in the respective holes. In another embodiment, each hole is a slot having a pair of generally parallel sides that taper or are shouldered in part towards the complementary slot, and the fastening element has the form of a strip with grooved edges to engage the tapering or shouldered sides of the slots so that the strip can be slid out of and into the slots.

Specific embodiments of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of a first embodiment of saw in accordance with the invention; Figure 2 is an enlarged view of the portion of the saw indicated by the circle 2 in Figure 1; Figure 3 is a sectioned view taken on the section line 3-3 in Figure 2; Figure 4 is similar to Figure 3, but exploded; Figure 5 is a side view of a second embodiment of saw in accordance with the invention; Figure 6 is an enlarged view of the portion of the saw indicated by the circle 6 in Figure 5; Figure 7 is similar to Figure 6, but with a fastening element removed; Figures 8 & 9 are sectioned views taken on the section lines 8-8 and 9-9, respectively, in Figure 6; and Figure 10 is similar to Figure 8, but exploded.

In both embodiments of the invention, a saw 10 comprises a blade 12 and a handle 14 affixed to the heel of the blade 12 by conventional means 16. The blade 12 comprises a cutting portion 18 secured to a support portion 20 by a number of fastening arrangements 22 spaced apart along the blade 12. The support portion 18 is generally similar in shape to a conventional rip saw or cross-cut saw blade and has a thickness T over the majority of its area. The cutting portion 18 has the form of a strip having a length generally equal to the length of the lower edge of the support portion 20 and a thickness T, along the lower cutting edge 24 of the cutting portion 18, generally the same as the thickness T of the support portion 20. The cutting edge 24 is formed with teeth 26 which may be alternately offset in a conventional fashion to provide a kerf K. Referring in particular to Figures 4 and 10, one side of the support portion 20 is rabbeted from its lower edge at a depth of half the thickness "T of the support portion 20 to form a rabbet 28 of width W. Furthermore, the opposite side of the cutting portion 18 is rabbeted from its upper edge at a depth of half the thickness "1 of the cutting portion 20 to form a rabbet 30 of generally the same width W. The rabbets 28,30 can therefore be fitted together to form a half-lapped joint so that, as shown in Figures 3, 8 and 9, the blade 12 has a uniform thickness I at the cutting edge 24 (ignoring the offset of the teeth 26), at the joint and across the remainder of the support portion 20.

Referring now specifically to the first embodiment shown in Figures 1 to 4, each of the fastening arrangements 22 that holds the cutting portion 18 to the support portion 20 comprises a circlip 32 fitted into aligned holes 34,36 through the cutting portion 18 and the support portion in the region of the rabbets 30,28.

The circlip 32 is of the internal Seeger type, but having a V-shaped groove 38 cut in its outer surface. The thickness T of the circlip is generally the same as the thickness I of the cutting edge 24, support portion 20 and the joint therebetween. In a preferred example, the groove 38 has a root angle A of 60 .

Each hole 34,36 is frustoconical, having sides 39 that taper toward the respective rabbet 30,28, and has a half-angle A generally equal to 90 -"A, i.e. 60 in the preferred example.

With the holes 34,36 aligned, the circlip 32 is compressed using suitable circlip pliers, inserted into the holes 34,36 and then released so that the tapering sides 39 around the holes 34,36 become engaged in the groove 38. The relative sizes of the groove 38 and the holes 34,36 are such that, upon release of the circlip pliers, the circlip 32 remains in compression so as to hold the cutting portion 18 and the support portion 20 firmly together.

The saw 10 may be used for sawing like a conventional hand saw. When it is desired to replace a blunt cutting portion 18 with a new one, or to replace one type of cutting portion 18 with a different one, the circlips 32 are removed using circlip pliers and the old cutting portion 18 is removed from the support portion 20. The replacement cutting portion is then placed with its rabbet 30 engaged with the rabbet 28 of the support portion 20 and with the holes 34,36 aligned, and the circlips 32 are inserted into the holes 34,36.

Referring now specifically to the second embodiment shown in Figures 5 to 10, each of the fastening arrangements 22 that holds the cutting portion 18 to the support portion 20 comprises a generally rectangular strip 40 of metal fitted into complementary, aligned, generally-rectangular slots 42,44 through the cutting portion 18 and the support portion 20 in the region of the rabbels 30,28.

The strip 40 has V-shaped grooves 46 cut in its longer edges. The thickness T of the strip 40 is generally the same as the thickness I of the cutting edge 24, support portion 20 and the joint therebetween. In a preferred example, the groove 46 has a root angle A of 600. The strip 40 is perforated adjacent one end by a slot 47 into which a small screwdriver blade or other tool can be fitted.

The longer edges of the slots 42,44 each have portions 48 that taper towards the respective rabbet 30,28, at an angle A generally equal to 90 -"A, i.e. 60 in the preferred example. The longer edges of the slots 42,44 each also have portions 50 adjacent on end of the slots 42,44 that are cut square.

With the slots 42,44 aligned, one end of the strip 40 is inserted into the ends of the slots 42,44 having the square cut edge portions 50. The ends of the grooves 46 in the strip 40 are then engaged with the ends of the tapering edge portions 48. The cutting and support portions 18,20 are then bowed so that the tapering edge portions 48 become more aligned with the grooves 46, and the strip 40 is then slid into the slots 42,44 with the tapering edge portions 48 sliding along the grooves 46. Once the strip 40 is fully inserted into the slots 42,44, the cutting and support portions 18,20 are relaxed, and as they straighten the opposite ends of the strip 40 become trapped between the opposite ends of the slots 42,44 so that the strip 40 is locked in position in the slots 42,44 and fastens the cutting and support portions 18,20 firmly together.

The saw 10 may be used for sawing like a conventional hand saw. When it is desired to replace a blunt cutting portion 18 with a new one, or to replace one type of cutting portion 18 with a different one, each strip 40 is removed by bowing the cutting and support portions 18,20 so that one end of the strip 40 protrudes from the slots 42,44 and then by using a screwdriver blade or other tool in the slot 47 to slide the strip 40 lengthways out of the slots 42,44. The replacement cutting portion is then placed with its rabbet 30 engaged with the rabbet 28 of the support portion 20 and with the slots 42,44 aligned, and the fastening strips 40 are inserted into the slots 42,44.

Various modifications and developments may be made to the embodiments of the invention described above. For example, the support portion 20 may be provided with a back extending along its upper edge to reinforce the panel of the support portion 20 so as to form a back saw, such as a tenon, dovetail or gents saw. Also, the rabbets 28,30 may be provided with other complementary, interengaging surface formations to assist the fastening arrangements in preventing relative longitudinal movement between the cutting and support portions 18,20.

Furthermore, the grooves 38,46 in the circlips 32 and fastening strips 40 may be square, rather than V-shaped, and the complementary portions 39,48 of the cutting and support portions 18,20 may be correspondingly stepped or shouldered, rather than tapered.

It will be appreciated that fastening arrangements 22 described above may be used for fastening laminar elements other than saw blade components together and indeed also for laminating one laminar element to some other possibly much thicker member.

It should be noted that the embodiments of the invention has been described above purely by way of example and that many other modifications and developments may be made thereto within the scope of the present invention.

Claims

CLAIMS

The reference nwnerals in the claims are no: intended to limit the scope of the claims.

1. A saw blade (12) having an elongate cutting portion (18) with a series of cutting teeth (26) and an elongate support portion (20) for supporting the cutting portion, the cutting portion and support portion being separately formed, and the saw blade further including means (22) for releasably fastening the cutting portion and the support portion together such that the cutting portion and fastening means lie within the kerf (K) of the blade.

2. A saw blade as claimed in claim 1, wherein the support portion lies within the kerf of the blade.

3. A saw blade as claimed in claim 1, wherein the support portion has a panel fastened to the cutting portion and a reinforcing back spaced from the cutting portion, and the panel lies within the kerf of the blade.

4. A saw blade as claimed in any preceding claim, wherein the cutting portion has a rabbeted portion (30) that engages with a complementary rabbeted portion (28) of the support portion to form a half-lapped joint.

5. A saw blade as claimed in claim 4, wherein the fastening means comprises a plurality of fastening arrangements (22) spaced apart along the length of the joint, each fastening arrangement including a releasable fastening element (32; 40) that engages in complementary holes (34,36; 42,44) in the rabbeted portions.

6. A saw blade as claimed in claim 5, wherein each hole in each rabbeted portion has at least a portion (39; 48) that tapers or is shouldered towards the respective complementary hole, and each fastening element has a groove (38; 46) that receives the tapering or shouldered portions of the respective holes.

7. A saw blade as claimed in claim 6, wherein each hole (34,36) is round, and each fastening element is provided by a grooved internal circlip (32) that can be contracted to remove the circlip from and replace it in the respective holes.

8. A saw blade as claimed in claim 6, wherein each hole is a slot (42,44) having a pair of generally parallel sides that taper or are shouldered in part (48) towards the complementary slot, and each fastening element has the form of a strip (40) with grooved edges (46) to engage the tapering or shouldered sides of the slots so that the strip can be slid out of and into the slots.

9. A saw blade as claimed in any preceding claim in combination with a further such cutting portion that can be used to replace the first-mentioned cutting portion.

10. A saw blade substantially as described with reference to Figures 1 to 4 or Figures 5 to of the drawings.

11. A hand saw (10) having a saw blade (12) as claimed in any preceding claim and a handle (14) attached to a heel end of the support portion.

12. A method of releasably laminating a laminar element (18) having first and second faces to a member (20), the method comprising the steps of: forming a first hole (34;42) through the laminar element, the first hole having at least a portion (39;48) that is tapered or shouldered towards the first face of the laminar element; forming a complementary second hole (36;44) in a surface of the member, the second hole having at least a portion (39;48) that is tapered or shouldered towards said surface of the member; assembling the laminar element and the member with the first face of the laminar element facing the surface of the member and with the holes aligned; and inserting a fastening element (32;40) into the holes, the fastening element having a groove (38;46) that receives the tapering or shouldered portions of the holes such that the fastening element fastens the laminar element to the member and such that the fastening element does not protrude significantly from the second face of the laminar element.

13. A method as claimed in claim 12, wherein the member is a second laminar element (20) having a second face opposite said surface, and the fastening element, once inserted, does not protrude significantly from the second face of the second laminar element.

14. A method of releasably laminating a laminar element to a member, substantially as described with reference to the drawings.

15. An assembly of a member (20) and a laminar element (18) having first and second faces releasably laminated to the member, wherein: a first hole (34;42) is fonned through the laminar element, the first hole having at least a portion (39;48) that is tapered or shouldered towards the first face of the laminar element; -10-a complementary second hole (36;44) is formed in a surface of the member, the second hole having at least a portion (39;48) that is tapered or shouldered towards said surface of the member; the laminar element and the member are assembled with the first face of the laminar element facing the surface of the member and with the holes aligned; and a fastening element (32;40) is disposed in the holes, the fastening element having a groove (38;46) that receives the tapering or shouldered portions of the holes such that the fastening element fastens the laminar element to the member and such that the fastening element does not protrude significantly from the second face of the laminar element.

16. An assembly as claimed in claim 15, wherein the member is a second laminar element (20) having a second face opposite said surface, and the fastening element does not protrude significantly from the second face of the second laminar element.

17. A method or assembly as claimed in claim 12, 13, 15 or 16, wherein each hole (34,36) is round, and the fastening element is provided by a grooved internal circlip (32) that can be contracted to remove the circlip from and replace it in the respective holes.

18. A method or assembly as claimed in claim 12, 13, 15 or 16, wherein each hole is a slot (42,44) having a pair of generally parallel sides that taper or are shouldered in part (48) towards the complementary slot, and the fastening element has the form of a strip (40) with grooved edges (46) to engage the tapering or shouldered sides of the slots so that the strip can be slid out of and into the slots.

19. An assembly of a member and a laminar element, substantially as described with reference to the drawings.