US2056948A

US2056948A - Carpenter's tool

Info

Publication number: US2056948A
Application number: US538833A
Authority: US
Inventors: Bernt M Bensen
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-05-20
Filing date: 1931-05-20
Publication date: 1936-10-13
Anticipated expiration: 1953-10-13

Description

od. 13, 1936. B. M.' BENSEN v2,056,941;

CARPENTER S TOOL Filed May 20, 1931 2 Sheets-Sheet 1 i Y INVENTOR f MW@ /UM 1 *ed* AT1-orme? Oct. 13, 1936. B M BENSEN l 2,056,948

CARPENTER S TOOL Filed May 20, 1931 2 Sheets-Sheet 2 Ber/zz M 5.012560 ATTORNEY Patented Oct. 13, 1936 UNITED STATES PATENT OFFICE CARPENTERS TOOL Bernt M. Bensen, Brooklyn, N. Y. Application May 20, 1931, Serial No. 538,833

26 Claims.

This invention relates to tools used by carpenters in the layout of roof rafters in a frame house structure.

In the present method of determining angles and other measurements required for the cutting of roof rafters, a tool or instrument, known as the carpenters square, is commonly used. This tool is so equipped with scales and tables of dimensions as to permit a carpenter, skilled in the art of building frame houses, to determine accurately the angles and other dimensions of roof rafters. The process however is quite lengthy and requires a number of intermediate steps of calculation and therefore the possibility of error is quite likely.

It is the object of my invention to provide a tool or instrument which will greatly simplify the determination of these various dimensions.

A more specific object is to provide a tool which may be set to a certain calibration indicating the lise in feet per foot of run of a common roof rafter and from which setting the angle of plumb cut and the length of the rafter per foot of run will both be determined.

A further object of my invention is to provide the required dimensions for jack, hip and valley rafters, all of which may be determined from respective settings of the tool to the rise in feet per foot of run.

The invention will be fully and comprehensively understood from a consideration of the following detailed description when read in connection with the accompanying drawings which form part of the application, with the understanding, however, that the improvement is capable of extended application and is not confined to the exact showing of the drawings nor to the precise construction described and, therefore, such changes and mod iiications may be made therein as do not affect the spirit of the invention nor exceed the scope thereof as expressed in the appended claims.

In the drawings:

Fig. l is a side elevational View of the tool, partly broken away to show the adjusting means.

Fig. 2 is a sectional view taken on the staggered line 2-2 of Fig. 1.

Fig. 3 is a sectional view taken on line 3--3 of Fig. 2, looking in the direction of the arrows.

Fig. 4 is a perspective view.

Fig. 5 is a reduced side elevational view of the pivoted blade of the tool showing the face of the blade opposite to that shown in Figs. 1 and 4.

Fig. 6 is a side elevational outline of a portion of the tool set to determine the angle of plumb cut and illustrates diagrammatically the fundamental principle upon which the use of this tool in determining the plumb out is based; and

Fig. '7 is a side elevational outline view of the tool set to determine the angle of side cut and illustrates diagrammatically the fundamental principle used to determine this dimension.

Referring to the drawings for a more detailed description thereof, numeral 5 indicates the body of the tool to which is pivoted a blade 6. The body 5 comprises strips 1 and 8 parallel to each other and spaced apart. A block 9 is interposed between the strips 1 and 8 at one end thereof, screws I being employed to secure the strips 1 and 8 together at the mentioned end. The blade 6 is disposed between the strips 1 and 8 at the other end. A pin l2, which passes thru the strips 1 and 8 and thru the blade 6, is employed to pivotally mount the blade between the mentioned strips. The nut l is threaded on an end portion of the pin I2 and provides a means to tighten the strips against the blade for the purpose of temporarily holding the blade in any desired position.

A screw l1 passes nally with the strips v1 and 8. The mentioned screw carries at its outer end a cylindrical member I8 fixed thereto. The shoulder 20 is formed on the screw l1, said shoulder being in contact with the inner face of the block 9 so that the screw I1 is kept from moving in either direction longitudinally but is adapted to be rotated. Beyond the shoulder the screw I1 is threaded, this threaded portion being adapted to engage an interiorly threaded member 2l, said member being provided with a threaded recess 22 to accommodate the mentioned screw. The member 2l carries at an end thereof an indicator 24 which extends upwardly and terminates in a point 25. The indicator 24 is provided at its lower portion with a second indicator member 26 in pivotal relation to the indicator 24 and rotatable about the axis of rotation indicated by the point 21. The exact relation between point 25 and point 21 and between point 21 and member 26 will hereinafter be specified. It will be readily understood that the indicator 24 and its indicator member 26 may be moved longitudinally of the body of the tool by turning the cylindrical member i8.

The fundamental principles upon which the operation of this tool is based requires certain specific limitations of proportion and construction. A standard unit of measurement or a fraction thereof is to be used as the distance between certain points on the tool. Altho the inventor has chosen one inch as the preferable unit, the tool may be adapted to use any other convenient standard unit of measurement. The distance measured vertically between point 21 and point 25 is equal to one inch. 'I'he axial point of the pin12 is located on a theoretical line in prolongation of the lower edge 6B of the blade 6. When the blade 6 is swung downwardly and around until its upper edge 6a contacts with the entire thru the block 9 longitudi- 20 under surface of the member 26. the standard unit of one inch will again be found as the distance measured perpendicular to edge 6B, and between edge 6B and the point 21. The distance measuredperpendicular to the upper edge of the body 5`and the point |2 is also one inch.

The instrument is provided with various scales,

the use of which will be hereinafter described. Y

Vnumerals 12, 24,36, e'tc.,'each major division-.be-

ing exactly one inch long, that is, the distance betweenzero point andcalibration 12 is exactly vone inch'andlikewise the distance between

calibrations

12 and 24 is exactly one inch. Each major division is subdivided into twelve equal parts. The member 26 functions only as an VindicatorY when the blade 6 is swung around to contact with this member26. The point at which this indication is most desirable would normally be on a line perpendicular to the longer edge of member 26 indicated by numeral 26a, said perpendicular line passing thru point 21. However, the'construction of the tool makes this indicator point invisible'and therefore said point Yis displaced along the edge of member 26 an arbitrary distance to a point on member 26 where itV is visible in actual practice one-half inch. This indicator point is designated by numeral25a on each face of member 26. The upper edge 6a of the blade 6 carries a scale 3| on Vits forward side, the zero point of which would normally be on a line perpendicular to said edge'and passing thru the axis of pin I2. The displacement of the indicator point on member 26 from its theoretical point to the point 26m beyond Vthe body 5 of the tool necessitates a simi- -lar displacement of the zero point from its theoretical location to a corrected point a like distance of one-half inch. From this zero point Y the scale 3| is provided with major divisions spaced similarly to those specified for the scale 13|)V and calibrated Vsimilarly to said scale 30.

These major divisions aresubdivided into twelve equal parts. The rear side of the blade 6, indicated by numeral 35, carries a scale 34 shown in Fig. 5. The function of this scale is Yto determine the angle of plumb cut of a hip or valley rafter when said rafter lies in a vertical plane which bisects the dihedral angle defined by the-adjacent house walls, that is, when the said rafter is positioned in a vertical plane at 45 angle'with each house wall line. It is toi be noted here that the plumb cut angle of a hip or valley rafter is determined on the basis of the number of inches of rise per foot of run of the common rafter in the structure. The angle of plumb cut of the common rafter and the angle of plumb cut of a hip or valley rafter have a certain ratiothat is equivalent to the cosine of the angle of 45. or V0.707. This, then, is the ratio between the major divisions of scale 3| and the major divisions of scale 34. In other words, each major division of scale 34 is exactly 0.707 inches long and calibrated, as shown in Fig. 5. The majorV divisions of Vscale 34 are subdivided Yinto twelve equal increments and therefore the subdivisions of scale 3| are in a ratio to subdivisions of scale 34 as '1:0.707. The origin or In order to eliminate any possibility of misunderstanding as to the meanings of certain terms, a brief deiinition of these terms follows. A ridge pole is the horizontal structural member positioned at the apex of the common rafters. AThe common rafter is a structural member placed at an angle between the lower roof line of the house kand the ridge pole. Hip and valley rafters are required only when the end of a house roof is bevelled similar to the sides of the roof. Jack rafters are the structural members positioned between the side or end of a house roof-line and the hip rafters. The plumb cut angle is the angle between the edge Yof a rafter in position and a Vertical plane. The side cut angle is that between the face of the rafter and the ridge pole measured on a horizontal plane. This angle on common rafters is always 90. The specification of the pitch of a roof is generally given in terms of rise per unit of run. For example, ten inch rise per foot of run.

The use of the tool to determine the plumb cut angle of and the length of a Vcommon rafter is as follows. Blade 6 is swung around to the lower side of body 5 untilY its edge 6a. contacts with the entire edge 26a of member 26, as shown in Fig. 6. It is assumed that the pitch of this common rafter is to be a 23 inch rise per foot of run. The screw |8 is rotatedV in either direction to move the indicator 25a to register with the tenth twenty-third subdivision on the scale 3|. The angle so determined between the body 5 and. the blade 6 is the angle of the plumb cut. The length of the rafter per foot of run is indicated directly on scale 30 by the indicator point 25.

The geometric derivation of these dimensions will be clearly understood by reference to the diagrammatic triangle illustrated in Fig. 6. A line between points l2 and 21 is the hypotenuse c of the triangle. A line from point I2 projecting upwardly perpendicular to edge 6a forms the base a of the triangle. A line from point 21 projecting upwardly and parallel to edge 6a. forms the side of the triangle. The base, side and hypotenuse of the triangle so formed are indicated respectively by letters a, b and c. Since the horizontal distance between points 2 and 21 is always the fundamental unit regardless of the setting of indicator 25a, and since the side b of the triangle is of a length proportionate to the rise per foot of run of a rafter, it will be observed that the angle X between the hypotenuse and this side b, that is, the'angle opposite the base a,

vbasis of the rise in feet per foot of run of the `common rafter, the blade 6 is again swung around to the position shown in Fig. 6 and the indicator point 25a is moved in either direction by turning cylindrical member |8 until the point 25a coincides with the subdivision on scale 34 which indicates the number of feet and inches of rise per foot of run of the common rafter. The angle of plumb cut for a hip orvalley rafter is again that between edge 6a and the adjacent edge of the body is by reason of the previously stipulated ratio between the scale 3| and the scale 34, that is, 1:0107. The derivation of the geometric principle upon which this operation is based is similarv to that described for the plumb cut of the common rafter. In other words, the diagrammatic triangle illustrated in Fig. 6 represents the basis for this derivation.

The angle of side cut for hip and valley rafters may now be determined from the same setting of the tool by swinging the blade 6 around from its lower position Fig. 6 to that sho-Wn in Fig. 7 until edge 6B of the blade 6 contacts with the point 25. The angle thus formed between the body 5 and the blade 6 is the required angle for the side cut of these rafters. The diagrammatic triangle shown in Fig. 'I illustrates the trigonometric principle employed in the determination of this angle. The base, side and hypotenuse are designated respectively by letters d, e and f. The angle of side cut is indicated by letter Y. Since the length of d is proportional to the length 'of run and since the side e is proportional to the length of the common rafter, then the angle Y is determined from the equation e cotangent Y The length of the hip or valley rafter is indicated directly on scale 3U where the point 25 coincides with this scale. The basis for this determination is similar to that described for the length of the common rafter.

The angle of plumb cut for the jack rafters is the same as that for common rafters and is therefore determined in the same Way.

What is claimed as new is:

1. A tool of the character described comprising a body having parallel edges, a blade pivoted on said body and having parallel edges, said pivot being in line with one of said blade edges, a scale on said blade calibrated in inches of rise per foot of run of a common rafter, an adjustable indicating blade stop on said body movable longitudinally thereof and adapted to limit the movement of said blade in one direction upon contact with the same and to be set relative to said scale, the angle between the blade and said body being the plumb cut angle for a common rafter.

2. A tool of the character described comprising a body having parallel edges, a blade pivoted on said body and having parallel edges, said pivot bein-g in line with one of said blade edges, a rst scale on said blade calibrated in inches of rise per foot of run of a common rafter, a second scale on said body, calibrated in inches to indicate the length of a common rafter per foot of run, an adjustable indicating blade stop on said body movable longitudinally thereof and adapted to limit the movement of said blade in one direction upon contact with the same and to be set relative to said first scale, the angle between the blade and said body being the plumb cut angle for a common rafter, the position of said stop relative to said second scale indicating the length of a common rafter.

3. A tool of the character described comprising a body having parallel edges, a blade pivoted on said body and having parallel edges, said pivot being in line with one of said blade edges, a scale on said blade calibrated in inches of rise per foot of run of a common rafter, an adjustable indicating blade stop on said body movable longitudinally thereof and adapted to limit the movement of said blade in one direction upon contact with the same and to be set relative to said scale, the angle between the Vblade and said body being the plumb cut angle for a hip or valley rafter.

4. A tool of the character described comprising a body having parallel edges, a blade pivoted on said body and having paralleledges, said pivot being inline with one of said blade edges, a first scale on said blade calibrated in inches of rise per foot of run oi a common rafter, a second scale on said body, calibrated in inches to indicate the length of a hip or Valley rafter per foot of run, an adjustable indicating blade stop on said body movable longitudinally thereof and adapted to limit the movement of said blade in one direction upon contact with the same and to be set relative to said first scale, the angle between the blade and said body being the plumb cut angle for a hip or valley rafter, the position of said stop relative to said second scale indicating the length or a hip or valley rafter.

5. A tool of the character described comprising a body havin-g parallel edges, a blade pivoted on said body and having parallel edges, said pivot being in line with one of said blade edges, a scale on said blade calibrated in inches of rise per foot of run of a common rafter, an adjustable indicating blade stop on said body movable longitudinally thereof and adapted to limit the movement of said blade in one direction upon contact with the same and to be set relative to said scale, the angle between the blade and said body being the plumb cut angle for a jack rafter.

6. A tool of the character described comprising a body having parallel edges, a blade pivoted on said body and having parallel edges, said pivot being in line with one of said blade edges, a first scale on said blade calibrated in inches of rise per foot of run of a common rafter, a second scale on said body, calibrated in inches to indicate the length of a hip or valley rafter per foot of run of a common rafter, an adjustable indicating blade stop on said body movable longitudinally thereof and adapted to limit the movement of said blade in one direction upon contact with the same and to be set relative to said scale, the angle between the blade and said body being the plumb cut angle for a hip or valley rafter. v

7. A tool of the character described comprising a body having parallel edges, a blade pivoted on said body and having parallel edges, said pivot being in line with one of said blade edges, a scale on said blade calibrated in inches of rise per foot of run of a common rafter, an adjustable indicating blade stop on said body and movable longitudinally thereof and adapted to limit the movement of said blade and to contact either edge of the same and tov be set relative to said scale, the angle between the blade and said body being the plumb cut angle for a hip or Valley rafter when the blade is on one side of said body in contact with said stop, and the angle between the blade and said body being the side cut angle for hip or valley rafter when the blade is on the other side of said body in contact with said stop.

l8. A tool of the character described comprising a body having parallel edges. a blade pivoted on said body and having parallel edges, said pivot being in line with one of said blade edges, a scale on said blade calibrated in inches of rise per foot ci run of a common rafter, an adjustable indicating blade stop on said body and movable longitudinally thereof and adapted to limit the movement of said blade and toY contact either edge of thesame and to be se-t relative to said scale, the

`angle-between the blade and said body being the contact with said stop.

9. A tool of the-character described comprising a body having parallel edges, a blade pivoted on said body and having parallel edges, said pivot Vbeing in line with one of said blade edges, a rst scale on said blade calibrated in inches of rise per foot of run of a common rafter, a second scale on said body calibrated to indicate the length of .a jack rafter per foot of run, an adjustable indicating blade stop on said body and movable longitudinally thereof and adapted to limit the movement of said blade and to contact either edge of the same and to be set relative-to said first scale', the angle between the blade and said body being the plumb cut angle for a jack rafter when the blade is on one side of said body in Contact with said stop and the .angle between the blade and said Y body being the side cut angle for a jack rafter when the blade is on the other side of said body in contact with saidstop, the position of saidstop relative to said second scaleindicating the length of a jack rafter per foot of run.

V10. A tool of the character described comprising a body having parallel edges, a blade pivoted on said body and having parallel edges, said pivot being in line with one of said blade edges, a first scale on said blade calibrated in inches of rise per foot of run of a common rafter, a second scale on said body calibrated to indicate the length of a hip orvalley rafter per foot of run, an adjustable indicating blade stop on said body and movable Y longitudinally thereof and adapted to limit the movement of said blade and to contact either edge of the same and to be set relative to said first scale, the angle between the blade andsaid body being Vthe plumb cut angle for a hip or valley rafter when the blade is on one side of said body in contact with said stopand the angle between the blade and said body being the side cut angle for a hip or valley rafter when the blade is on the other side of said body in contact with said stop, the position of said stop relative to said second scale indicating the` length of a hip or valley rafter per foot of run of a common rafter.

1l. A tool comprisinga scaled body portion, a scaled blade pivoted on said body portion and having parallel edges, an indicator movable length- `wise of said body portion and against which either edge Vof said blade may contact, said indicator having ends, said indicator having at one 'end a point for contact with the blade and having between its ends a point which is at the intersection of a line parallel to one edge of the body portion and passing thru the pivotal point and of a line which is perpendicular to the same edge of the body portion and passes thru said contact point, the distance from said point to one end of the indicator contacted by said blade being equal to the distance from said point to the far edge of the blade when the latter is swung around to contact the other end of the indicator.

12. VA tool comprising a body having a scale calibrated in feet of rise per foot of run, a blade pivoted on said body, an indicator blade stop movable lengthwise ofsaid body, adjacent said Scale, and adapted to determine the position of said blade on either side of said body, said stop being so proportioned relative to the width of the blade Aand being so pivoted that, for a given setting of the blade stop the angle between the body and the blade on one side of the body and resting against said stop is to the angle between the body and the blade on the other side of the body and resting against said stop as the sine of the rst angle is to the tangent of the second angle.

13. A tool comprising .a scaled body portion, a scaled blade pivoted on said body and having parallel edges, an indicator movable lengthwise of said body portion and against which either edge of said blade may contact, saidindicator having ends, said indicator having at one end a point for contact with the blade and having between its ends a point which is at the intersection of a line parallel to one edge of the body portion ,and pass- Ving through the pivotal point and of a line which is perpendicular to the same edge of the body portion and passes through said contact point, the distance from saidpoint to one end of the indicator contacted by said blade being equal to the distance from said point to the far edge of the blade when the latter is swung around to contact the other end of the indicator, the pivotal point of the blade being on a line with one edge of the blade.

14. A tool of the character described comprising a body, a blade pivoted on said body, the axis of rotation formed by said pivot being in line with an edge of said blade, a scale on said blade calibrated to indicate the rise per'foot of run of a common rafter, an adjustable indicating blade stop on said body movable relative to said pivot and adapted to determine the position of said blade and to be set relative to said scale, the angle between the blade and said body being the plumb cut angle for a common rafter,

15. A tool of the character described comprising a body, a blade pivoted on said body, the axis of rotation formed by said pivot being in line with an edge of said blade, a rst scale on said Y blade calibrated to indicate the rise per foot of run of a common rafter, a second scale on Said body calibrated to indicate .the length of,

a common rafter per foot of run, an adjustable indicating blade stop on said body movable relative to said pivot and adapted to determine the angular position of said blade, and to be set relative to said first scale, the angle between the blade and said body being the plumb cut angle l for a common rafter, and the position of said stop relative to said second scale indicating the length of a common rafter.

16. A tool of the character described comprising a body,` a scale on said body, a blade pivoted on said body, the axis of rotation formed by said pivot being in line with anedge of said blade, a scale on said blade calibratedto indicate the rise per foot of run of a common rafter, an adjustable indicating blade stop on said body movable along said body scale relative to said pivot and adapted to engage said edge-of the blade and thus determine the angular position of said blade.

1'7. A tool of the character described comprising a body, a blade pivoted on said body, the axis of rotation formed by said pivot being in line with an edge of said blade, a rst scale on said blade calibrated to indicate the rise per foot of run of a common rafter, a second scale on said body calibrated to indicate the length of a hip or valley rafter per foot of run, an adjustable relative to said rst scale, the angle between the blade and said body being the plumb cut angle for a hip or valley rafter, the position of said stop relative to said second scale indicating the length of a hip or valley rafter.

18. A tool of the character described comprising a body, a blade pivoted on said body, the axis of rotation formed by said pivot being in line with one of said blade edges, a first scale on said blade calibrated to indicate the rise per foot of run of a common rafter, a second scale on said body calibrated to indicate the length of a hip or valley rafter per foot of run of a common raiter, an adjustable indicating blade stop on said body movable relative to said pivot and adapted to determine the angular position of said blade and to be set relative to said first named scale, the angle between the blade and said body being the plumb cut angle for a hip or valley rafter.

19. A tool of the character described comprising a body, a blade pivoted on said body, the axis of rotation formed by said pivot being in line with an edge oi said blade, a first scale on said blade calibrated to indicate the rise per foot of run of a common rafter, a second scale on said body calibrated to indicate the length of a hip or valley rafter per foot of run of a common raiter, an adjustable indicating blade stop on said body movable relative to said pivot and adapted to determine the angular position of said blade and to be set relative to said first named scale, the angle between the blade and said body being the plumb cut angle for a hip or valley rafter.

20. A tool of the character described comprising a body, a scale on said body, a blade pivoted on said body and having parallel edges, a scale on said blade, an indicator movable relative to the blade pivot on said body and against which either edge of said blade may contact, said indicator having at one end a point for contact with the blade and having between its ends a point which is at the intersection of a line parallel to one edge of the body, and passing through the pivotal point and of a line which is perpendicular to the same edge of the body and which passes through said contact point, the distance from said point to one end of the indicator contacted by said blade being proportional to the distance between the divisions of said blade scale.

21. A tool of the character described comprising a body having a scale the divisions of which indicate the rise per foot of run of a common rafter, a blade pivoted on said body, an indicator blade stop movable lengthwise of said body adjacent said scale and including an indicator point on one side of the body coacting with the scale to determine the position of said blade on said body, said stop extending transversely across the body and so proportioned relative to the divisions of said scale so that for a given setting of the blade stop the angle between the body and the blade is a trigonometric function of the length on the blade scale indicated by the stop indicator point with the blade resting against the end of the stop opposite the indicator point.

22. A tool of the character described comprising a body, a blade pivoted on said body and having a straight edge which if extended would pass through the axis of the blade pivot, a blade adjustment means adapted to vary the angle of said blade, said means having a point on a line parallel to said body and passing through said blade pivot, and having a second point at which said blade adjustment is effective in its engagement with said straight edge, the line passing thru both of said points being constantly at a right angle to said first line.

23. A tool of the character described comprising a body, a blade pivoted on said body and adapted to be swung about towards opposite edges of the body into either one of two operative positions, a blade adjustment means adapted to vary the angle of said blade in either of said two positions, said means having a point on a line parallel to said body and passing through said blade pivot, and having a second point at which said blade adjustment is effective when the blade is in contact therewith, the line passing through said two points being constantly at a right angle to that longitudinal edge of said blade which contacts with the blade adjusting means.

24. A tool ofthe character described comprising a body, a blade pivoted on said body, a scale on said blade calibrated into major and mino'r graduations, a blade adjustment means adapted to vary the angle of said blade, said means having a point on a line parallel to said body and passing through said blade pivot, and having a second point at which said blade adjustment is effective, the line passing through both of said points on the blade adjustment means being constantly at a right angle to said first line, said points on the blade adjustment l means being spaced a distance equal to one of the major divisions of said blade scale.

25. A tool of the character described comprising a body, a blade pivoted on said body, a scale on said blade, a blade adjustment means adapted to vary the angle of said blade, said means having a point on a line parallel to said body and passing through said blade pivot, and having a second point at which said blade adjustment is effective, the line passing through both of said points on the adjustment means being constantly at a right angle to the same longitudinal edge of said blade, said points being spaced a distance equal to one of the unit distances of the divisions of said blade scale.

26. A device of the class described comprising a body having opposing parallel edges, a blade having opposing parallel edges and pivoted to the body, said blade adapted to be swung about its pivot outwardly of the body to cause opposing edges of the blade to intersect the opposing edges of the body, meansl adjustable longitudinally of the body and provided at opposite ends with stops against which the blade engages in its two positions to t the angles formed between the opposite edges of the blade and the adjacent edges of the body in the several operative angle forming positions of the blade, a point in said means being in a line extending longitudinally of the body and passing through the axis of the blade, the ldistance between one of said stops and its coacting blade edge measured from said point with the blade in one of its positions being equal to the shortest distance between the other stop and the same blade edge similarly measured from said point.

BERNT M. BENSEN.