WO1995024609A1

WO1995024609A1 - Apparatus for measuring angles for mitres and bevels

Info

Publication number: WO1995024609A1
Application number: PCT/GB1995/000497
Authority: WO
Inventors: John Kelly Fox
Original assignee: John Kelly Fox
Priority date: 1994-03-09
Filing date: 1995-03-08
Publication date: 1995-09-14
Also published as: GB2301443B; AU1855395A; GB9404593D0; GB2301443A; GB9617973D0

Abstract

Apparatus (16) for measuring angles for mitres and bevels, which apparatus (16) comprises a pair of first arms (18, 20) which are pivotally connected together by a first pivot member (22), a pair of second arms (26, 28) which are pivotally connected together by a second pivot member (30), and third and fourth pivot members (38, 40) which pivotally connect the first arms (18, 20) to the second arms (26, 28), and the apparatus (16) being characterised in that it is constructed for being abutted against the edge of workpieces (54) whilst the workpiece (54) are marked with a requird angle. The apparatus (16) preferably includes a marker member (58) and an angle measuring member such as a protractor (62).

Description

APPARATUS FOR MEASURING ANGLES FOR MITRES AND BEVELS

This invention relates to apparatus for measuring angles for mitres and bevels.

A simple mitre box is known for use in cutting mitres. A workpiece to be cut, for example a picture moulding or an architrave, is placed in the mitre box and pre-set saw guides in the mitre box act to control the action of a saw and enable an accurate cut to be obtained, for example a 45° cut. Mitre jigs are known for use in cutting larger workpieces, for example heavy mouldings or architraves. These mitre jigs also have hole saw guides for controlling the action of a saw and giving a cut at a required angle. The mitre jigs can be set at any angle required and this makes them more versatile than the mitre box.

Electric power mitre saws are also known. These electric power mitre saws can then be adjusted to any angle. Furthermore, the blade of the electric power mitre saws can be tilted for cutting roof spars, rafters and the like.

The problem with all of the above mentioned mitre apparatus is that the operator has to determine the exact angle that is required in advance of cutting the workpiece and setting up the apparatus. The determining of the required mitre angle is an irritating and time consuming job that has faced joiners, carpenters and other persons for many years. If, for example, architraves have to be fitted around a door way, then angles can easily be determined if the doorway is square. It is simply necessary to use a normal known combination square. This gives the user a 90° angle and a pre-set 45° angle. The required mitre angle is 45°. However, if the door way is not square, then the combination square is no good as the angle of the mitre will not be half of 90°, ie 45°.

Where it is not possible to use a combination square, tradesmen often use a bevel. The bevel can be pushed against a lintel of a door frame at the corner against the upright of the frame and locked. This gives the bevel angle but the actual mitre angle needed to enable architraves, mouldings and the like to be cut neatly still has to be worked out. One known way is to hold the bevel against a protractor in order to obtain the correct bevel angle, and then to divide the bevel angle in half in order to obtain the mitre angle. This operation works fine in theory but not in practice and often mitre joints so measured just do not fit. Making corrections to ensure that the mitre joints fit is time consuming and often corrective carpentry leaves the original workpiece, for example the architrave or moulding, too short, so that the original workpiece has to be discarded with consequent increased expense.

The above described method of using a bevel is also used by joiners in fitting windowsills around bay windows, and in fitting skirting or shelves around or into awkward openings or recesses which are not square. Expensive mouldings going upstairs are often rendered unsightly due to non-square mitres.

The above problems have led many tradesmen to try and obtain correct mitre angles by overlapping two pieces of wood or other material to be mitred. This enables the joiner to mark both pieces of wood and to bisect the drawn lines in order to obtain the required mitre angle. Difficulty is often encountered in holding the two pieces of wood still and it is very easy to get the measurements wrong. On bay windows, the operation is even more difficult as the sills first have to be cut to the bevel angle to enable the pieces of wood to be laid in place overlapping one another. After marking the wood, lifting off the wood, bisecting the lines and then cutting, mistakes often occur and the pieces of wood rarely fit accurately first time.

It will be appreciated from the above that there is a need for apparatus that will automatically set a required mitre angle, and that is able to act as the missing link between a known combination square and a known bevel. It is an aim of the present invention to provide such apparatus.

Accordingly, the present invention provides apparatus for measuring angles for mitres and bevels, which apparatus comprises a pair of first arms which are pivotally connected together by a first pivot member, a pair of second arms which are pivotally connected together by a second pivot member, and third and fourth pivot members which pivotally connect the first arms to the second arms, and the apparatus being characterised in that it is constructed for being abutted against the edge of workpieces whilst the workpieces are marked with a required angle.

The apparatus of the present invention can be used for automatically setting mitre angles and for providing a means of accurately measuring all angles for mitres and bevels, which are required to be able to set any mitre jig or powered mitre saw. The apparatus can additionally be used simply to mark an accurate mitre on to a workpiece such for example as a piece of wood or other material, quickly and easily whatever the situation.

Preferably, the apparatus is one in which at least one of the arms is constructed to be of a thickness which allows the abutting against the workpieces. Usually, two of the arms will be constructed to be of a thickness which allows the abutting against the workpieces. If relatively thin arms are employed, then the arms may be provided with separate abutment members such for example as pins or pads.

Preferably, the apparatus is one in which one of the first arms allows the abutting and comprises a pair of arm members positioned one on top of each other, and in which one of the second arms allows the abutting and comprises a pair of arm members positioned one on top of each other. As an alternative to having pairs of arm members on top of one another, a single thicker arm member can be used and appropriately slotted.

The apparatus may be one in which the first pivot member is adjacent that part of the apparatus used for measuring internal angles, in which the second pivot member is adjacent that part of the apparatus used for measuring external angles, and in which the first and the second pivot members are unencumbered by other parts of the apparatus so that workpieces can be marked by drawing a straight line to extend substantially completely between the first and the second pivot members.

Preferably, the apparatus includes an angle measuring member. The apparatus is preferably one in which the angle measuring member is a protractor which is located on one of the first arms and which comprises at least one of a mitre angle scale and a bevel angle scale. Preferably the protractor comprises a mitre angle scale, a bevel angle scale, and a pitch angle scale.

The apparatus may be one in which the protractor is located on one of the first arms such that the radial centre of the protractor is at the fourth pivot member, and in which the second arm which is pivotally connected by the fourth pivot member includes a viewing window for viewing the protractor. Advantageously, the viewing window includes magnifyer means for facilitating reading of the protractor.

If desired, the protractor may have measuring scales on both of its sides so that the apparatus can then be used working from either face, for right-handed situations or left-handed situations. When the protractor has measuring scales on both of its sides, then these measuring scales may be the same or different. If different measuring scales are employed, then one side of the protractor may have a mitre angle scale, a bevel angle scale and a pitch angle scale, and the other side of the protractor may have a pitch angle scale and a scale giving the vertical angle to pitch.

Preferably, the apparatus includes at least one spirit level. This enables a tradesman to easily know when a part of the apparatus is being held at a true horizontal or at a true vertical.

Preferably, the apparatus includes a marker member connected between the first and the second pivot members. The marker member may have a slot which extends over a majority of the length of the marker member, and the second pivot member may then extend through the slot.

Preferably, the apparatus is one in which the second pivot member is positioned at a distance from the third and the fourth pivot members which is equal to the distance of the first pivot member from the third and the fourth pivot members. Also preferably, the second arms are longer than the first arms.

The. apparatus may advantageously include locking means for locking the arms of the apparatus in a chosen position. The locking means may lock the arms at 90° giving an accurate 90° angle and an accurate mitre of 45°, or the locking means may lock the arms at any other position that is required.

Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which:

Figure 1 illustrates the difficulty of measuring an angle using a combination square; Figure 2 illustrates the difficulty of measuring an angle using a bevel measuring tool;

Figure 3 further illustrates the difficulty of obtaining a precise mitre angle using the bevel measuring tool;

Figure 4 shows first apparatus of the invention in a situation similar to that shown in Figure 3;

Figures 5 - 13 show the apparatus of Figure 4 in different measuring situations;

Figure 14 shows second apparatus of the invention and illustrates how the apparatus can be used as a T- square;

Figures 15 - 18 show different ways to use the second apparatus of the invention;

Figure 19 shows front and rear sides of a protractor as used in the apparatus of the invention;

Figure 20 shows another protractor;

Figure 21 shows third apparatus of the invention;

Figures 22 and 23 show fourth apparatus of the invention; and

Figure 24 shows fifth apparatus of the invention.

Referring to Figure 1, it will be seen that a combination square 2 is being used to measure an angle 4 in the corner of a doorway 6. It can be seen that the combination square 2 is no good because the angle 4 is greater than 90°. A pre-set 45° mitre is also not satisfactory in this circumstance.

Figure 2 illustrates how the angle 4 can be obtained as an opened size on a bevel tool 8 but the bevel tool 8 does not give any means of halfing this angle to obtain the required mitre angle. Similar problems can be seen from Figure 3 where bevel tools 8 are being used to try and measure an internal angle 10 and at external angle 12 on brick work 14.

Figure 4 shows first apparatus 16 which is in accordance with the invention and which is for automatically setting mitres and for measuring angles for mitres and bevels. The apparatus 16 comprises a pair of first arms 18, 20 which are pivotally connected together with a first pivot member 22 positioned at a first end 24 of the first arms 18, 20.

The apparatus 16 further comprises a pair of second arms 26, 28 which are pivotally connected together by a second pivot member 30. The second pivot member 30 is positioned at a point 32 intermediate first and second ends 34, 36 respectively of the second arms 26, 28.

The apparatus 16 still further comprises a third pivot member 38 and a fourth pivot member 40. The third pivot member 38 is positioned at a second end 42 of the first arm 18. The third and fourth pivot members 38, 40 pivotally connect the first arms 18, 20 to the second arms 26, 28.

The second pivot member 30 is positioned at a distance from the third and the fourth pivot members 38, 40 which is equal to the distance of the first pivot member 22 from the third and the fourth pivot members 38, 40. As can be seen, the second arms 26, 28 are longer than the first arms 18, 20.

The apparatus 16 is such that the first arm 18 comprises a pair of arm members 46, 48 positioned one on top of each other, and the second arm 28 comprises a pair of arm members 50, 52 positioned one on top of each other. The first arm 20 locates between the arm members 46, 48 and 50, 52. The second arm 26 locates between the arm members 46, 48 and 50, 52. The arm members 46, 48 and 50, 52 cause the arms 18, 28 to be of such a thickness that the apparatus 16 is able to be abutted against the edge of workpieces such as planks of wood 54 as shown in Figure 4. If all the arms 18, 20, 26, 28 were thin, then difficulty would be encountered in abutting the apparatus 16 against the edges of the wood 54.

The pivot member 40 is provided with locking means in the form of a lever nut 56. When the lever nut 56 is tightened, then the arms 18, 20, 26, 28 are locked in position. A second locking means can lock the apparatus of the invention at a fixed 90°. This second locking means may be a thumb screw or other simple locking device, and it ensures that, when locked, the apparatus will give an accurate 90° angle and an accurate 45° angle, these being the most common angles used in the building trade.

The apparatus 16 further comprises a marker member 58. The marker member 58 is a flat member and it has a slot 60 which extends over the majority of the length of the marker member 58 as shown. The marker member 58 is able to slide relatively to the remainder of the apparatus 16 to a desired position for angle marking purposes.

The apparatus 16 further comprises an angle measuring, member in the form of a protractor 62. The protractor 62 is provided with a mitre angle scale 64, a bevel angle scale 66 and a pitch angle scale 68.

The apparatus 16 still further comprises a spirit level device 70 for determining when appropriate parts of the apparatus are positioned horizontally or vertically, for example when a tradesman is working out the pitch angle of a stair stringer, a roof rafter or the like.

As will be appreciated from Figure 4, the apparatus 62 is able to be used to obtain the functions of both a combination square 2 and a bevel tool 8. The apparatus 2 has the added advantage of being able to cope with all other angles and mitres that are outside the scope of the combination square 2 and the bevel tool 8. As can be seen from Figure 4, the apparatus 16 can be pressed internally or externally on to brickwork 72 forming, for example, part of a bay window. The apparatus 16 can be locked in position using the lever nut 56, thereby automatically setting the bevel angle and, more importantly, the mitre angle. The appropriate angle on the protractor 62 can be seen through a window 74 formed in the arm 28. Advantageously, the window 74 is provided with magnifyer means such as a magnifying glass in order to facilitate reading of the appropriate scales 64, 66, 68 on the protractor 62. Once an appropriate angle has been determined, this angle may be set on a mitre jig or on an electric power mitre saw. Alternatively, the angle can be simply marked on the wood 54 by lifting the apparatus straight on to the wood 54, where it is held abutted against an edge of the wood 54 and the required angle is marked.

Figure 5 shows the apparatus 16 pushed around a corner 76 to find a correct mitre, for example for skirting or a windowsill.

Figure 6 shows the apparatus 16 being pushed into the corner 76 to set the mitre angle. Figure 7 shows how the apparatus 16 can be abutted against three different pieces of wood 54, each of different widths.

Figures 8 and 9 illustrate how the apparatus 16 can be abutted against different parts of stairs 78 to obtain different required angles.

Figure 10 shows the apparatus 16 being used to mark a piece of wood 54.

Figures 11 and 12 show the apparatus 16 being used on a roof 80. In Figure 11, the apparatus 16 has measured the pitch of the roof 80 simply by being placed as shown on the roof 80 and the arm 28 moved vertically until the spirit level 70 indicates that the arm 28 is in the horizontal position. Figure 12 shows how the apparatus 16 may be placed to set the pitch on the protractor 62 to the required pitch in the vertical. Figure 12 also illustrates the use of an extension arm 82 which is able to be connected to the arm 26 as shown by a bolt 84 screwing through a hole 86 in the extension arm 82 and into a threaded hole 88 in the arm 26.

Figure 13 shows how the apparatus 16 abuts against an edge 90 of a piece of wood 54. The abutting is such that the apparatus 16 is able to be held firmly in position with the marker member 58 positioned adjacent a side face 92 of the wood 54, the side face 92 needing marking prior to cutting of the wood 5 . Figure 14 illustrates second apparatus 16 in accordance with the invention. This second apparatus 16 is like the apparatus 16 shown in Figure 4 but the arm 26 is provided with an extension arm 82. The extension arm 82 is secured in position by two screw bolts 84 which screw into two of the threaded holes 88 in the arm 26. The extension arm 82 can be held in position by any simple means. For clarity of illustration, Figure 14 shows a standard T-square 96 and it will be seen that the arm 26 corresponds to the arm 98 on the T-square 96, and the arms 26, 82 correspond to the leg 100 on the T- square 96. Slots 102 allow for adjustment and/or marking as may be desired.

Figures 15 and 16 show the apparatus of Figure 14 but with .the extension arm 82 fixed in different positions. In Figure 15, the extension arm 82 is secured by the screw bolts 84 in one of the threaded holes 88 in the arm 26 and also in one of two threaded holes 104 in the arm 20. Figure 16 shows the extension arm 82 held in position by the screw bolts 84 on top of the arm 18.

Figures 17 and 18 show the apparatus 16 with the extension arm 82 secured to the marker member 58. In this case, the screw bolts 84 connect to nuts 106 as shown in Figure 18, this being because the screw bolts 84 pass through the slot 60 in the marker member 58. Figure 19 shows how the arm 20 has a front face 108 and a rear face 110. The front face 108 is such that the corresponding front face of the protractor 62 has the scales 64, 66, 68. The rear face 110 is such that the corresponding rear face of the protractor 62 has an outer scale 112 giving a roof pitch angle, and an inner scale 114 giving the vertical to the roof pitch angle. In Figure 19, the illustrated protractor 62 could be formed as one single protractor or as two separate protractors which are secured together. Figure 19 also illustrates how the protractor 62 may be a removable protractor 62 held in position by screws 116. A removable protractor 62 is an alternative to forming the protractor 62 as an integral part of the arm 20.

Figure 20 shows an ordinary protractor 118 with scales 120, 122.

Figure 21 shows third apparatus 16 having one protractor 62 and another protractor 124. As shown, the protractor 62 is provided with a pair of holes 128 for receiving the screws 116. The protractor 124 is provided with a central cut-out portion 130 which receives the pivot member 38. The protractor 62 is only provided with the bevel angle scale 66 and the pitch angle scale 68, the pitch angle obtained obviously being such that it does not exceed 90°. The protractor 124 has the mitre angle scale 64. Figures 22 and 23 show fourth apparatus 16 which uses a protractor 62 having just the bevel angle scale 66 and the pitch angle scale 68. The arm 28 has an upper scale 130 and a lower scale 132. When a bevel angle is read from the bevel angle scale 66 in the window 74, then the lower scale 132 can be read until the same reading is obtained. It is then only necessary to look at the upper scale 130 to obtain the mitre angle. Thus the two scales 130, 132 act as a ready reckoner for dividing a measured bevel angle in half to obtain the mitre angle.

It is to be appreciated that the embodiments of the invention described above with reference to the accompanying drawings have been given by way of example only and .that modifications may be effected. Thus, for example, spirit level devices 134 may optionally be provided where shown. Also, various holes, which are preferably screw threaded, may be provided as shown to enable one or more extension arms 82 to be connected where required to the apparatus 16. If desired, the necessary depth for the arms 18, 28 may be achieved by making each of the arms 18, 28 as a single member and then providing slots where necessary to allow operation of the apparatus 16. Where the protractor 62 is detachable, it may be reversed for viewing only from one side. If the protractor 62 is to be left in position and it is to be viewed from both sides, then two windows 74 will normally be employed, one for viewing each side of the protractor 62. More than one lever nut 56 may be employed for locking the arms of the apparatus together.

Claims

1. Apparatus for measuring angles for mitres and bevels, which apparatus comprises a pair of first arms which are pivotally connected together by a first pivot member, a pair of second arms which are pivotally connected together by a second pivot member, and third and fourth pivot members which pivotally connect the first arms to the second arms, and the apparatus being characterised in that it is constructed for being abutted against the edge of workpieces whilst the workpieces are marked with a required angle.

2. Apparatus according to claim l in which at least one of the arms is constructed to be of a thickness which allows the abutting against the workpieces.

3. Apparatus according to claim 2 in which one of the first arms allows the abutting and comprises a pair of arm members positioned one on top of each other, and in each one of the second arms allows the abutting and comprises a pair of arm members positioned one on top of each other.

4. Apparatus according to any one of the preceding claims in which the first pivot member is adjacent that part of the apparatus used for measuring internal angles, in which the second pivot member is adjacent that part of the apparatus used for measuring external angles, and in which the first and the second pivot members are unencumbered by other parts of the apparatus so that the workpieces can be marked by drawing a straight line to extend substantially completely between the first and the second pivot members.

5. Apparatus according to any one of the preceding claims and including an angle measuring member.

6. Apparatus according to claim 5 in which the angle measuring member is a protractor which is located on one of the first arms and which comprises at least one of a mitre angle scale and a bevel angle scale.

7. Apparatus according to claim 6 in which the protractor comprises a mitre angle scale, a bevel angle scale, and a pitch angle scale.

8. Apparatus according to claim 6 or claim 7 in which the protractor is located on one of the first arms such that the radial centre of the protractor is at the fourth pivot member, and in which the second arm which is pivotally connected by the fourth pivot member includes a viewing window for viewing the protractor.

9. Apparatus according to claim 8 in which the viewing window includes magnifyer means for facilitating reading of the protractor.

10. Apparatus according to any one of claims 6 to 9 in which the protractor has measuring scales on both of its sides so that the apparatus can be used either face up as required for left and right hand use.

11. Apparatus according to any one of the preceding claims and including at least one spirit level.

12. Apparatus according to any one of the preceding claims and including a marker member connected between the first and the second pivot members.

13. Apparatus according to claim 12 in which the marker member has a slot which extends over the majority of the length of the marker member, and in which the second pivot member extends through the slot.

14. Apparatus according to any one of the preceding claims in which the second pivot member is positioned at a distance from the third and the fourth pivot members which is equal to the distance of the first pivot member from the third and the fourth pivot members.

15. Apparatus according to any one of the preceding claims in which the second arms are longer than the first arms.

16. Apparatus according to any one of the preceding claims and including locking means for locking the arms of the apparatus in a chosen position.