NZ567847A - A mitre box and guide inserts - Google Patents

Abstract

A mitre box assembly is disclosed, the mitre box assembly includes a mitre box with a plurality of opposing integrally formed slots, and one or more detachable inserts arranged to be located within the slots. The inserts include an integrally formed guiding means for guiding a saw.

Description

567847 1QQ55652382* ;5 6 7 8 4 7 ;Our Ref: HOW002 Patents Form No. 5 ;PATENTS ACT 1953 COMPLETE SPECIFICATION ;A MITRE BOX AND GUIDE INSERTS ;I, Robert Grant Howard, a New Zealand citizen of 11 Winston Avenue, Palmerston North, New Zealand, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: ;Intellectual Property Office of * 3 0 APR 2Q08 RECEIVEOJ 567847 2 A MITRE BOX AND GUIDE INSERTS FIELD OF THE INVENTION The present invention relates to a mitre box and guide inserts. In particular, the present invention relates to a mitre box assembly including a mitre box, a mitre box with a clamping mechanism and guide inserts for use therein.

BACKGROUND Mitre boxes are known tools that are used to enable a workman to cut an angled edge on a work piece. By providing prefixed angled slots in a box, accurate cuts to work pieces can be completed to enable a work piece to be placed flush against an angled surface or another work piece to form a mitred joint.

In its simplest form, a mitre box is made from wood and includes a number of opposing slots within the walls of the box. The slots are arranged at specific angles on the walls to enable the user to cut mitred joints on work pieces. Normally, the work piece is held by the user in position within the mitre box while 20 the user cuts the work piece. As the work piece is not fixed in position this can result in inaccurate cuts being made into the work piece.

In US patent US 5,171,003 a clamping mechanism is described for use on a mitre box. The clamping mechanism includes a single drive shaft that can be 25 pushed up against a work piece and locked in position to stop the work piece from moving while it is being cut. However, the drive shaft only provides one clamping point, and also only provides a uniform transfer of the force applied to the drive shaft to clamp the work piece in place.

Prior known mitre boxes also have the problem whereby the slots formed in the walls of the box are too wide and thus provide some inaccuracy when it comes to cutting a mitred joint due to the movement of the saw blade within the slot.

For mitre boxes that have narrower slots, the slots can become widened through 35 continuous use over time thus reducing the accuracy of the cuts made. When this occurs, the user is then required to purchase or make a new mitre box. 567847 3 An Emir 25A mitre box is available from various providers, such as at http://www.diytools.co.uk. This mitre box is provided with a number of guides that can be attached to the top of the wall of the mitre box. The nylon saw guides can be adjusted to fit any number of saw widths in order to provide some guidance 5 when sawing. However, the slots within the box itself are still liable to damage from the saw blade as it enters and leaves the slots as saw blades are fairly flexible. Therefore, the box would need to be replaced at regular intervals otherwise increasingly inaccurate cuts could occur.

The present invention aims to overcome, or at least alleviate, some or all of the afore-mentioned problems, or to at least provide the public with a useful choice.

SUMMARY OF THE INVENTION According to one aspect, the present invention provides a mitre box assembly including a mitre box with a plurality of opposing integrally formed slots, and one or more detachable inserts arranged to be located within the slots, wherein the inserts include an integrally formed guiding means for guiding a saw.

According to a further aspect, the present invention provides a guide insert arranged to be attached within a slot of a mitre box, wherein the insert includes an integrally formed guiding means for guiding a saw. 2 h JUL 2009 RECEIVED 567847 4 BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1A shows a top perspective view of a mitre box assembly according to an embodiment of the present invention; Figure 1B shows a bottom perspective view of a mitre box assembly according to an embodiment of the present invention; Figure 2A shows a perspective view of a guide insert according to an embodiment of the present invention; Figure 2B shows a front view of a guide insert according to an embodiment of the present invention; Figure 3A shows a perspective view of a mitre box without any guide inserts 15 according to an embodiment of the present invention; Figure 3B shows detail of a slot in the mitre box of figure 3A according to an embodiment of the present invention; Figure 4A shows a top perspective view of a clamping mechanism according to an embodiment of the present invention; Figure 4B shows a bottom perspective view of a clamping mechanism according to an embodiment of the present invention; Figure 5 shows a mitre box assembly in use according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION First Embodiment Figure 1A shows a top perspective view of a mitre box assembly 101. The 30 assembly includes a mitre box 103 made of a plastics material. In this embodiment, the box is made out of PC-ABS, which is a blend of polycarbonate and ABS (Acrylonitrile Butadine Styrene). Attached to the mitre box 103 are a number of detachable inserts 105, which are also made out of a plastics material INTELLECTTAl ^O^ERTY OFFICE OF HZ. 2 <i JUL 2009 RECEIVED 567847 including a glass portion. In this embodiment, the material is GF-Nylon (glass-filled nylon). The glass content is preferably high and in the region of around 50 to 70%. However, other mixes are also envisaged using the same or alternative materials. The inserts 105 are located within slots 107 formed within walls 109 of 5 the mitre box 103. The inserts 105 will be described in more detail below.

The slots within the mitre box 103 are integrally formed within the walls 109 of the mitre box 103 such that pairs of slots (107A, 107B, 107C) are positioned and aligned to face each other.

The mitre box walls extend from a base 111. The slots 107 that are formed in the walls 109 also extend along the base. That is each pair of slots formed in the walls has an interconnecting slot formed within the base. The slots thus provide a channel within which the blade of a saw can pass through in order to cut 15 through a work piece placed within the mitre box. Each pair of slots is arranged at different positions along the walls of the mitre box and arranged at different angles relative to a clamped work piece in order to provide different cutting angles for the work piece located within the mitre box. In this particular embodiment two pairs of slots (107A) are provided for cutting mitres of a 22.5 20 degree angle, two pairs of slots (107B) are provided for cutting mitres of a 45 degree angle and two pairs of slots (107C) are provided for cutting mitres of a 90 degree angle thus providing a total of 6 pairs of slots or 12 slots in total.

Extending from each side of the base of the mitre box is an extended surface 25 arranged to provide a fixing means as well as a guidance mechanism for filing.

The fixing means are formed from securing apertures 113 that are holes formed through the extended surface on each side of the mitre box. The holes may be used to secure the mitre box to a work surface by passing a fastener, such as a 30 screw, through the hole and into the work surface to secure the mitre box against the work surface. This will then negate the user from having to hold onto the mitre box assembly while cutting work pieces.

The filing guidance mechanism is provided by formed raised portions 115 which 35 provide a raised surface above the base 111. The raised portions 115 are shaped to provide an angled surface perpendicular to the base surface which can 567847 6 be used to guide a file when filing the edges of the work piece. Two angled surfaces are provided at 45 degrees and 90 degrees on each side of the mitre box.

Formed within the base 111 are two clamp guide slots 117 that provide a longitudinal aperture through which a portion of a clamping mechanism can pass in order to clamp the work piece in place while making the required cut, The clamping mechanism can also be seen in the bottom view of the mitre box 10 assembly shown in figure 1B. A drive shaft 119 is provided that is positioned through an aperture 120 within the front wall of the mitre box. At one end of the drive shaft is a knob 121 upon which a user can apply pressure in order to move the drive shaft through the aperture.

A locking mechanism is provided that includes a locking plate 122. The locking mechanism locks the drive shaft movement in a first direction and allows the drive shaft to move freely in a second direction. That is, the knob can be pushed towards the mitre box freely, wherein the drive shaft freely bypasses the locking plate and passes through the aperture 120. However, movement in the opposite 20 direction is inhibited by the locking plate 109 through the action of the locking plate being forced down on to the drive shaft at an angle. Movement of the drive shaft in this opposite direction can be enabled by releasing the locking plate so that it no longer applies a force against the drive shaft.

A clamp 123 is pivotally attached to the drive shaft on the underside of the mitre box such that movement of the driveshaft in one direction causes the clamp to also move in that general direction. Due to the pivotal arrangement, the amount of movement required along the length of the clamp to clamp a work piece in place can vary depending on the shape of the work piece that is being clamped 30 into position. That is, the clamping mechanism is arranged such that non uniform work pieces can be clamped securely.

A pair of apertures 124 is provided through a drive shaft casing to enable the clamping mechanism to be attached, using a fastening device such as a screw, 35 to the underside of the mitre box. 567847 7 Jaws 125 are attached to opposite ends of the clamp 123 via a jaw holding device 126. The jaws are positioned on the upper side of the mitre box by allowing the jaw holding device 126 to pass through the clamp guide slots 117 to attach to the clamp 123.

The clamping mechanism will be described in more detail below with reference to figure 4.

Also located on the underside of the mitre box are feet 127 to provide a gripping 10 force when the mitre box is placed on a work surface.

Figures 2A and 2B show a perspective view and front view of a guide insert 105.

The guide insert 105 includes a guiding means 201 including a V-shaped 15 opening 205 in the upper surface of the insert. The V-shaped opening narrows into and towards a guide channel 203 formed from the upper surface of the insert through the centre of the body down towards, but ending shortly before, the lower end of the insert. The upper opening 205 is formed by two chamfered surfaces (207A, 207B).

Viewing the insert from a front perspective as shown in figure 2A, the insert includes a front opening 209 formed from two chamfered surfaces (211 A, 211B) and a rear opening 213 formed from two chamfered surfaces (not shown but correspond to chamfered surfaces 211A and 211B).

The upper opening 205 provides a guide through which the lower edge of the blade of the saw can pass into the insert from the top and then enter into the guide channel. The front and rear openings (209, 213) provide a guide through which the leading edge of the saw can enter into the guide channel from the front 30 or rear of the mitre box.

The dimensions of the inserts are such that a saw blade can locate within the guide channel whilst being hindered from moving laterally by any substantial amount. However, the dimensions ensure that the saw blade is not tight within 35 the guide channel such that movement of the saw blade is impeded by the surfaces of the guide channel. It will be understood that various dimensions may 567847 8 be used for different sized saw blades. The differing dimensions would only result in differing dimension for the various openings, guiding means and guide channels but the overall dimensions of the insert would be the same to enable the insert to fit into the slot of the mitre box.

Extending from a lower surface of the insert are locking means 215. The locking means include two opposed snap lock clips (217A, 217B). The clips are flexible to allow the clip to move and snap lock into a locking recess formed within the slot of the mitre box.

Extending from the upper surface of the insert are locating means (219A, 219B). The locating means are formed from two extending portions that extend out from the upper surface and then extend at a right angle in line with the length of the insert. The locating means are positioned within locating recesses formed next to 15 an upper end of the slots of the mitre box when the insert is fitted.

Figures 3A and 3B show a perspective view of a mitre box without any guide inserts and detail of a slot respectively. These views show the locating recesses 301 and locking recesses 303 formed as part of the slot within the mitre box. 20 Figure 3A shows the general view of the mitre box without any inserts inserted. The view in Figure 3B is a close up view of the area identified by 'A' in Figure 3A. As can be seen, the inserts are able to be located and secured in place within the mitre box using the recesses 301 and 303. If the inserts are gradually worn down through use or are damaged, they can easily be removed by unclipping the snap 25 lock clips and lifting out the inserts from the slots. A replacement insert can then be inserted. By replacing the inserts at regular intervals, the accuracy of the angled cut made using the mitre box is maintained without the need to replace the entire mitre box.

The clamping mechanism of the mitre box will now be explained in more detail. Figures 4A and 4B show a top and bottom perspective view of the clamping mechanism 401. The drive shaft 119 and clamp 123 are joined together pivotally at a pivot point 403 by a pin placed through the drive shaft and into the clamp. The clamp is joined to the drive shaft at a point approximately halfway along the 35 clamp's length. This enables the clamp 123 to pivot or turn with respect to the drive shaft 119. The drive shaft is located within a drive shaft casing 405, which 567847 9 is subsequently attached to the underside of the mitre box using the recesses 124 as mentioned above. This allows the drive shaft and clamp to move relative to the mitre box casing.

The locking mechanism 407 described above can be seen in more detail in figure 4A. The mechanism includes the locking plate 122 and a resilient device 409, such as a spring, that provides a force against the locking plate to bias the lower portion of the plate in a direction such that its lower edge pushes against the surface of the drive shaft at an angle. By biasing the locking late in this manner, 10 the drive shaft is able to freely move in one direction but is locked in the opposite direction unless the locking plate is released. Thus, as the drive shaft is pushed in a first direction towards the work piece, the work piece is locked in position by the jaws on the clamp. The clamp is unable to move in a direction substantially opposite to the first direction as it is connected to the drive shaft, which in turn is 15 not able to move in that opposite direction due to the locking plate. Upon releasing the locking plate, the work piece can be released from the clamping mechanism.

Figure 5 shows a mitre box assembly in use. The assembly 101 is used to 20 clamp a work piece 501 in position to enable a mitre to be cut through a work piece. The work piece 501 is placed on the base of the mitre box at a position such that one of the slots in the mitre box aligns with the required cut line on the work piece. The knob attached to the drive shaft is pushed by the user so that the clamp is moved in a direction generally towards the work piece, albeit 25 underneath the base of the mitre box. The jaws on the upper side of the mitre box are thus moved towards the work piece to lock the work piece in place as they are attached to the clamp via the jaw holding device 126 through the clamp guide slots 117.

When one of the jaws 125 comes into contact with the work piece 501 and the work piece is moved up against the back wall of the mitre box, the clamp is caused to rotate at the pivot point 403 until the second jaw comes up against a stop. In figure 5 the stop is shown to be the back wall of the mitre box, however it will be understood that the stop may be another surface of the work piece. 35 Therefore, the clamping mechanism is able to clamp irregularly shaped work 567847 pieces securely within the mitre box, as well as clamping shorter work pieces by utilising only one of the jaws attached to the clamp.

Thus, the clamping mechanism can clamp a non-uniform cross sectional work 5 piece by driving the drive shaft and pivoting the clamp towards the work piece to a position that is non-perpendicular to the drive shaft. That is, a longitudinal force is applied to the drive shaft and is non-uniformly transferred to the ends of the clamp to clamp the work piece into position.

Once the work piece is locked in position by the clamping mechanism, the user can insert a saw blade within the guide channels of a pair of inserts located within a pair of slots integrally formed within the mitre box. The user is then able to saw through the work piece at the angle required to create the mitre cut.

Further Embodiments It will be understood that the embodiments of the present invention described herein are by way of example only, and that various changes and modifications may be made without departing from the scope of invention.

It will be understood that materials other than those specifically mentioned may be utilised to form the mitre box and inserts.

Further, it will be understood that the configuration of slots may differ to that 25 shown and described, and that the number of slots formed in the mitre box may vary. 567847 n

Claims (23)

CLAIMS:

1. A mitre box assembly including a mitre box with a plurality of opposing 5 integrally formed slots, and one or more detachable inserts arranged to be located within the slots, wherein the inserts include an integrally formed guiding means for guiding a saw.

2. The mitre box assembly of claim 1, wherein the insert includes a locking 10 means and the mitre box includes a locking recess located at a first end of the slot, and the locking means is arranged to semi permanently attach to the locking recess to lock the insert into position within the slot.

3. The mitre box assembly of claim 2, wherein the locking means includes 15 two opposed snap lock clips arranged to semi permanently attach to and detach from the locking recess.

4. The mitre box assembly of claim 3, wherein the clips are arranged to attach to the locking recess when the insert is inserted fully into the slot. 20

5. The mitre box assembly of claim 1, wherein the guiding means includes a guide channel and an upper opening located at a first end of the guide channel, the upper opening being formed by first and second chamfered surfaces that narrows towards the guide channel. 25

6. The mitre box assembly of claim 5, wherein the guide channel includes a front opening formed by third and fourth chamfered surfaces that narrow towards the guide channel. 30 7. The mitre box assembly of claim 5, wherein the guide channel includes a rear opening formed by fifth and sixth chamfered surfaces that narrow towards the guide channel. intellectual property

OFFICE OF N.z. 26 AUG 2009 received 567847 12

8. The mitre box assembly of claim 1, wherein the one or more inserts include locating means and the mitre box includes a locating recess formed at a second end of each slot, and the locating means is arranged to locate within the 5 locating recess.

9. A guide insert arranged to be attached within a slot of a mitre box, wherein the insert includes an integrally formed guiding means for guiding a saw.

10 10. The guide insert of claim 9, further including a locking means arranged to semi permanently attach to a locking recess within the mitre box to lock the insert into position within the slot.

11. The guide insert of claim 10, wherein the locking means includes two 15 opposed flexible clips arranged to semi permanently attach to and detach from the locking recess.

12. The guide insert of claim 11, wherein the flexible clips are arranged to attach to the locking recess when the insert is inserted fully into the slot. 20 25

13. The guide insert of claim 9, wherein the guiding means includes a guide channel and an upper opening located at a first end of the guide channel, the upper opening being formed by first and second chamfered surfaces that narrows towards the guide channel.

14. The guide insert of claim 13, wherein the guide channel includes a front opening formed by third and fourth chamfered surfaces that narrow towards the guide channel. 30

15. The guide insert of claim 13, wherein the guide channel includes a rear opening formed by fifth and sixth chamfered surfaces that narrow towards the guide channel.

16. The guide insert of claim 9, further including locating means and the 35 locating means is arranged to locate within a locating recess formed on the mitre box. intellectual property office of n.z 26 AUG 2009 RECEIVED 567847 13

17. The mitre box assembly of claim 1, wherein the mitre box further includes a clamping mechanism, the clamping mechanism including a drive shaft and a clamp, wherein: 5 the clamp is pivotally connected to the drive shaft, the clamping mechanism is arranged to clamp a non-uniform cross sectional work piece though the application of a longitudinal force applied to the drive shaft, and the clamp is arranged to non uniformly transfer the force applied to the drive shaft to the ends of the clamp. 10

18. The mitre box assembly of claim 1, wherein the mitre box further includes a clamping mechanism, the clamping mechanism including a drive shaft and a clamp, wherein: the clamp is pivotally connected to the drive shaft, 15 the clamping mechanism is arranged to clamp a non-uniform cross sectional work piece by driving the drive shaft and pivoting the clamp towards the work piece to a position that is non-perpendicular to the drive shaft. 20

19. The mitre box assembly of claim 17 or claim 18, wherein the clamp is pivotally connected to the drive shaft substantially halfway along the length of the clamp.

20. The mitre box assembly of claim 17 or claim 18, wherein the mitre box 25 further includes a locking mechanism arranged to lock the drive shaft movement in a first direction and allow the drive shaft to move freely in a second direction.

21. The mitre box assembly of claim 20, wherein the locking mechanism is arranged to allow the drive shaft to move freely in the first direction by releasing a 30 locking plate.

22. The mitre box assembly of claim 17 or claim 18, wherein the mitre box further includes two or more clamp guide slots formed in a base of the mitre box, and the clamping mechanism further including two or more jaws connected to the 35 clamp, wherein the clamp guide slots are arranged to provide a the jaws to move parallel with upon driving the drive shaft. fTOWtt' PROPERTY office of n.z. 26 AUG 2009 RECEIVED 567847 14

23. The mitre box assembly of claim 22, wherein the jaws are attached to each distal end of the clamp. ROBERT GRANT HOWARD 10 / By His Attorneys ELL||S VERB^EKET TERRY intellectual property necir" nc z 2 3 AUG 2009 16 i.i,£lVED