GB2493125A

GB2493125A - Protractor

Info

Publication number: GB2493125A
Application number: GB1102038.5A
Authority: GB
Inventors: Darren Portfleet
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-02-07
Filing date: 2011-02-07
Publication date: 2013-01-30
Also published as: GB201102038D0

Abstract

A protractor 10 comprises a body portion 12 having at least a first straight side, a rotatable element 16 mounted for rotation relative to the body portion 12, a ruler 14 having at least a first straight side, the ruler 14 being mounted to the rotatable element 16, an angular scale 18 indicating the angle between the respective straight sides of the ruler 14 and body portion 12, and positioning means mounted between the body portion 12 and the rotatable element 16 for positioning the ruler 14 and body portion 12 in one of a plurality of pre-determined angular positions relative to one-another, the positioning means includes a plurality of angularly spaced recesses (40, fig 3) and a spring biased latching means (spring plunger 34) for engaging in one of the recesses.

Description

TITLE: PROTRACTOR The presetn invention relates to a protractor and particularly, bitt not exclusively, to a bevel protractor for measuring and marking angles in carpentry, cabinet work, metal work and plastics work.

BACKGROUND TO THE INVENTION

It is known to provide a bevel protractor for use in carpentry, woodwork and other crafts for measuring and marking off angles. The protractor may be part of a set, known as a combination square, in which 9(IY and 45° set squares and a ruler are also provided.

A problem of a combination square is that it comprises several parts, for use independently, depending on the angle to be marked off These parts have to be carried ancL'or stored and are cumbersome. Furthermore, the length of the ruler, which generally is removably attached to the protractor, is often too short, for example, when marking off an angle on a board.

A solution to these problems was proposed in the applicant's earlier application PCT/G82009/00253 1. However, this device proved unworkable, in that the hinged portions of the ruler did not naturally provide a flat ruler on which the body portion could traverse. Furthcrmore, the sliding arrangement tended to jam and the detents tended to lock the rotary mount to the body portion.

It is an object of the invention to provide a protractor which substantially reduces or obviates the problems associated with combination squares and substantially solves the problem associated with the applicant's earlier device.

SUMMARY OF INVENTION

According to the first aspect of the present invention there is provided a protractor comprising a body portion having at least a first straight side, a rotatable element mounted for rotation relative to thc body portion, a ruler having at least a first straight side, the ruler being mounted to the rotatable element, an angular scale indicating the angle between the respective straight sides of the ruler and body portion, and positioning means mounted between the body portion and the rotatable element for positioning the ruler and body portion in one of a plurality of pie-determined angular positions relative to one-another, the positioning means includes a plurality of angularly spaced recesses and a spring biased latching means for engaging in one of the recesses.

The protractor is advantageous because the positioning means allows the ruler to be positioned at certain angular positions relative to the body portion without having to use a set square. The use of a spring biased latching means relieves frictional pressure between the rotatable element and the body portion and facilitates free movement between the pre-determined angular settings.

The latching means may be a spring loaded ball bearing. This ensures that when one of the recesses is engaged with the ball bearing, the rotatable element is biased to a locked position, retaining the angular positioning between the ruler and the body portion until adequate pressure is applied to the spring mechanism to release the rotatable element from the locked position.

Eight recesses may be provided at 45° angular spacing. This is useful because 45° and 90° angles are commonly required to be marked. The positioning means may also retain the ruler and the body position a.t angles greater than 90°, allowing greater flexibility when a user is utilising the protractor. It should be appreciated that more recesses may be provided, for example, twelve recesses at 30° angular spacing, if desired.

The recesses may be provided on the body portion or the rotatable element and the latching means extends from the rotatable element or body portion respectively.

Preferably, the recesses are provided in a substantially flat surface of the rotatable element rather than being positioned extending from the periphery of the rotatable element. This further facilitates engagement and release of the latching means.

Furthermore, the use of a ball bearing reduces the frictional contact between the rotatable element and the body portion.

Advantageously, a substantially circular cut-away may be provided on the body portion for receiving the rotatable element, the depth of the cut-away being less than the thickness of the rotatable element. This allows the ruler, which is connected to the rotatable clement, to rotate relative to the body portion freely without obstruction.

over 360°.

A central pin may be provided for releasably connecting the rotatable element, the body portion, and the angular scale. The central pin may have an elongate head of dow-tail cross section for locating and engaging a longitudinal dove-tail slot provided on the ruler.

The ruler may include a plurality of ruler portions, a dove-tail slot extending centrally and longitudinally along each of the ruler portions for engaging with the dove-tail head of the central pin, the ruler sliding relative to the central pin. This allows a seamless transition between rider portions, allowing the central pin and the rotatable element, the body portion, and the angular scale retaining on the central pin to slide from one ruler portion to Mother unimpeded. Furthermore, the ruler can be adjusted to a desired length to one or both sides of the body portion, for use in situations when the ruler is too long or marking of an angle to both sides of the protractor is required.

Advantageously, the rider portions may be rtieasably connectable. This allows the length of thc ruler to be adjusted by simply adjusting the number of ruler portions connected. This means that the length of the ruler may be extended for marking large work-pieces, or be reduced when marking smaller work-pieces or when work space is limited.

The connection between adjacent ruler portions may be achieved by two pins extending from an end of one ruler portion engaging in complimentary apertures provided on the end of another ruler portion.

The extended ruler may be approximately im in length. Different lengths of ruler may optionally be provided, e.g. 0.5m, 0.75ni and l.25in.

The stem of Ike central pin may be non-circular. The central bore through the rotatable clement, and/or the angular scale1 is correspondingly non-circular. The rotatable element and/or the angular scale is therefore fixed relative to the central pin and does not rotate about the central pin. The body portion can therefore rotate independently of the central pin, rotating element and the angular scale.

The tail end of the central pin may be threaded for receiving a knurled nut, for locking the ruler relative to the body portion in a desired angularposition.

A fixed marking may be provided on the body portion and may align with markings on the angular scale.

The body portion may have a second side, parallel with the first side and a spirit level disposed between the first and second sides for indicating when one of the sides is horizontal. This enables the protractor to be used as a carpenter's level.

A second spiiit level may be disposed between the first and second sides for indicating when one of the sides is vertical.

BREEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 shows a schematic perspective view of a protractor when not in usc; Figure 2 shows a schematic peispective view of the protractor of Figure 1 when in use with one ruler portion; Figure 3 shows a schematic perspective view of a body portion, a rotatable element and a central pin of the protractor of Figure 1; Figure 4 shows a schematic perspective view of the rotatable element and the body portion engaged with the central pin, an angular scale and a knurled nut of the protractor of Figure 1; and FigureS shows a schematic view of the central pin of the protractor of Figure 1.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring firstly to Figures 1 and 2, a protractor is indicated generally at 10. The protractor 10 includes a body portion 12, a ruler 14 slidably conncctahlc to the body portion, a rotatable element 16 and an angular scale 18 releasably mounted on the body portion 12. A central pin 20 extends through the rotatable clement 16, body portion 12, and the angular scale 18 and locks them together by means ofaknutied nut 22.

The body portion 12 is substantially rectangular with two parallel sides 24. The thickness of the body portion 12 is typically around 10mm its length is typically 190mm, although these dimensions may be different for different sizes of protractor 10.

Referring also to Figure 3, a substantially circular cut-away region 26 is provided in the back of one end of the body portion 12 and serves as a supporting surftce for the rotatable element 16. A circular aperture 28 is provided through the body portion 12 at the centre of the circular cut-away region 26 and a counter-born 301s provided around the circular aperture 28. A threaded born 32 is provided through the body portion 12 positioned within the circular cut-away region 26 lying part way along a radius extending from the circular aperture 28. A latch is screwed into the threaded bore 32, the latch taking the form of a spring plunger 34 with a ball bearing spring loaded within the end of an aperture of a grub screw. Referring also to Figure 4, the other end of the spring plunger 34 can be seen protruding through the top of the body portion 12.

Referring back to Figure 3, the rotatable element 16 is a substantially flat circular disc. A circular boss 36, is provided at the centre of and extends from one side of the rotatable element 16. The boss 36 sits in the counter-bore 30 on the cut-away region 26 of the body portion 12. The radius of the rotatable clement 16 is substantially similar to that of the cut-away region 26. A substantially non-circular aperture 38 is provided through the centre of the rotatable element 16 and aligns with the circular aperture 28 of the body portion 12. The Thickness of the rotatable element 16 is slightly greater Than the depth of the cut-away region 26 of the body portion 12, such that when the ruler 14 locates on top of the rotatable element 16 there is clearance between the ruler 14 and the body portion 12. The depth of the cut-away region 26 is typically 3.5mm and the thickness of the rotatable element 16 is typically 4.5mm, although these dimensions may vary to suit.

Eight recesses 40 are provided in the surtbce of the rotatable element 16, on the same side as the circular boss 36. Each recess 4Ois angularly spaced 450 apart from each adjacent recess 40 and each is positioned part way along a radius extending from the non-circular aperture 38. This has the same distance between the spring plunger 34 and the circular aperture 32 of the body portion 12 so that the ball besting of the spring plunger 34 can be accommodated into any one of the recesses 40.

Referring to Figure 5, an elongate head 42 with a dove-tail cross section is provided at one end of the central pin 20. A stem 44 of the central pin 20 is substantially non-circular and compliments the shape of the aperture 38 of the rotatable element 16.

Therefore when the rotatable element 16 and the body portion 12 are engaged on the central pin 20 through their respective apertures 28, 38, the rotatable element rotates in tandem with The central pin 20, whereas the body portion 12 rotates independently from the central pin 20. The tail end 46 of the central pin is threaded to receive the knurled nut 22, as shown in Figures 1 and 2.

Referring to Figure 1, three ruler portions 48, each measuring around 310mm in length, are provided to form the extended ruler 14. The ruler portion 48 can be made to other suitable lengths and more or less ruler portions may be provided to form the extended ruler 14. The ruler 14 is provided with a graduated scale. In this embodimenç on one edge of the ruler 14 ii provided with a metric scale and on the other edge is an imperial scale. A dove-tail slot 50 extends centrally and longitudinally along each of the ruler portions 48 for engaging with the dove-tail head 42 of the central pin 20. The ruler portions 48 are connected by two pins 52 extending front one end of one ruler portion 48 engaging in complimentary apertures provided on the cud of another ruler portion 48.

Adjacent each end of the ruler portion 48 where the two apertures are provided, a bore is provided for receiving an adjustable detent 54. A corresponding groove 56 is provided on the periphery of each pin 52 at a position so that when each pin 52 of a ruler portion 48 is accommodated into each aperture of another ruler portion 48, the detent 54 engages with the groove 56 on one of the pins 52. To break the connection between adjacent rider portions 48, increased force can be applied to disengagc the pin 52 from the detent 54. The detent 54 therefore prevents unintentional separation of the ruler portions 48 in use. The length of the titter 14 can be varied by adjusting the number of ruler portions 48 connected. Two resilient clips 58 are used to hold together the ruler portions 48 of the disconnected ruler 14, as shown in Figure 1, when theprotractorlOisnotinuse.

Referring to Figures 1 and 4, the angular scale 18 is substantially frustoconical and it sits on the top of the body portion 12, at the same end as the rotatable clement 16. A circular grove is provided on the underside of the angular scale 18 to accommodate the portion of the spring plunger 34 that is protruding through the surface of the body portion 12. A substantially non-circular aperture 60, sized and shaped substantially similar to the aperture 38 of the rotatable clement 16, is provided through the centre of the angular scale 1% and aligns with the circular aperture 2% of the body portion 12 and the non-circular aperture 38 of the rotatable element 16. Through the aperture 60, the central pin 20 connects the angular scale 18 to the body portion 12 and the rotatable element 16. The knurled nut 22 is screwed on to the central pin 20, substantially abutting the angular scale 18. The angular scale 16 can be read against a reference marking 62, best shown in Figure 1, provided on the body portion 12 immediately adjacent the angular scale 16. In the position shown in Figure 2, the ruler l4ispresentedat225°tothebodyportionlZ Referring to Figure 1, cut-outs 64, 66 are provided between the sides 24 of the body portion 12, in which are mounted respective spirit levels 68, 70. The first spirit level 68 is disposed paraDe) with the sides 24 of the body portion 12, and the second spirit level lois disposed at 90° relative to the sides 24 of the body portion 12.

In use, the protractor 10 is typically stored and carried in the position as shown in Figure!, where the body portion 12 overlies the rulerportions 48 ofthe ruler 14. The ruler portions 48 overlie one another and are held together by two resilient clips 58.

The rotatable element 16, body portion 12 and the angular scale arc connected through the central pin 20 and held in place by the knurled nut 22. Furthermore, the position of the ruler 14 relative to the body portion 12 can be locked by means of the knurled nut 22.

When the protractor 10 is required, the resilient clips 58 are removed and the ruler portions 48 are connected to one another through the pins 54 and the apertures on the ruler portions until a desired length is achieved. If an angle needs to be measured on both sides of the body portion 12, the position of the ruler 14 relative to the body portion 12 can be adjusted by releasing the burled nut 22, allowing the body portion 12 to slide along the dove-tail slot 50 of the ruler 14. When the desired position is achieved the ruler 14 can be locked in position by tightening the knurled nut 22.

The body portion 12 can rotate about the central pin relative to the ruler 14, rotatable element 16, angular scale 18 and the knurled nut 22 to any desired angle.

Furthermore, each recess 40 on the rotatable element 16 is able to engage with the ball bearing of the spring plunger 34 when the ruler portion 12 rotates. The body portion 12 can therefbre automatically locate and be locked at multiples of 45° relative to the ruler 14.

When the protractor 10 is no longer required, the body portion 12 can be rotated back to be aligned with the ruler 14, i.e. at 00 on the scale. The knurled nut 22 can be released to slide the body portion 12 to a suitable position relative to the ruler 14. The ruler portions 48 can be disconnected from each other and the resilient clips 58 are used to hold them together.

It will be appreciated, that the protnctor is highly adaptable, since it can be used as a spirit level, a 45° set square and a 90° set square. As well as 45° and 90°, it can also

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automatically locate other angles at multiples of 45°, allowing greater flexibility of use fix a user. The protractor can also be used directly as a ruler and optionally the ruler can be completely removed from the body portion thereby enabling the ruler to be used independently. The protractor substantially obviates the need for a traditional combination square and is considered to be a highly adaptable multipurpose tool.

Claims

<claim-text>CLAMS1. A protractor comprising a body portion having at least a first straight side, a rotatable element mounted for rotation relative to Ike body portion, a ruler having at least a first straight side, the ruler being mounted to the rotatable element, an angular scale indicating the angle between the respective straight sides of the ruler and body portion, and positioning means mounted between the body portion and the rotatable element for positioning the ruler and body portion in one of a plurality of pzv-determined angular positions relative to one-another, the positioning means includes a plurality of angularly spaced recesses and a spring biased latching means for engaging in one of the recesses.</claim-text> <claim-text>2. Aprotractorasclaimedinclaiml,inwhichthelatchingmeansisaspring loaded ball bearing.</claim-text> <claim-text>3. A protractor as claimed in claim I or claim 2, in which eight recesses are provided at 45° angular spacing.</claim-text> <claim-text>4. Aprotraetorasclaimedinanyoneofclaimslto3,inwbichtherecessesare provided on the body portion or Ike rotatable element and the latching means extends from the rotatable element or body portion respectively.</claim-text> <claim-text>5. A protractor as claimed in any preceding claim, hi which a substantially circular cut-away is provided on the body portion for receiving the rotatable element, the depth of the cut-away being less than the thickness of the rotatable element.</claim-text> <claim-text>6. A protractor as claimed in any preceding claim, in which a central pin is provided for relcasably connecting the rotatable element, the body portion, and the angular scale.</claim-text> <claim-text>7. A protractor as claimed in claim 6, in which the central pin has an elongate head of dove-tail cross section for locating and engaging a longitudinal dove-tail slot provided on the ruler.</claim-text> <claim-text>8. A protractor as cf aimed in claim 7, in which the ruler includes a plurality of ruler portions, a dove-tail slot extending centrally and longitudinally along each of the ruler portions for engaging with the dove-tail head of the central pin, the ruler sliding relative to the central pin.</claim-text> <claim-text>9. A protractor as claimed in claim 8, in which the ruler portions are releasablyconnectable.</claim-text> <claim-text>10.A protractor as claimed in claim 9, in which the connection between adjacent ruler portions is achieved by two pins extending from an end of one ruler portion engaging in complimentary apertures provided on the end of another ruler portion.</claim-text> <claim-text>I]. A protractor as claimed in any preceding claim, in which the extended ruler is approximately im in length.</claim-text> <claim-text>12. A protractor as claimed in any one of claims 6 to 1, in which the stem of the central pin is non-circular.</claim-text> <claim-text>13. A protractor as claimed in claim 12, in which the central bore through the rotatable element is correspondingly non-circular.</claim-text> <claim-text>14. A protractor as claimed in claim 12 or claim 13, in which the central bore through the angular scale is correspondingly non-circular.</claim-text> <claim-text>15. A protractor as claimed in any one of claims 6 to 14, in which a tail end of the central pin is threaded for receiving a knurled nut.</claim-text> <claim-text>16. A protractor as churned in any one of preceding claim, in which a fixed macking is provided on the body portion and aligns with markings on the angular scale.</claim-text> <claim-text>17. A protractor as claimed in any one of preceding claim, in which the body portion has a second side, parallel with the first side and a spirit level disposed between the first and second sides for indicating when one of the sides is horizontaL.IIiS. A protractor as claimed in claim ii, in winch a second spirit level is disposed between the first and second sides for indicating when one of the sides is verticaL 19. A protractor substantially as described herein with reference to and as illusirazed in Figures 1-5 of the accompanying drawings.</claim-text>