US2107670A - Device for gauging the cutting of rafters - Google Patents

Description

Feb. 8, 1938. 5.o, KARLsoN DEVICE FOR GAUGING THE CUTTING OF' RAFTERS BY *MPW ATTORNEYS Patented Feb. 8, 1938 UNITED STATES PATENT OFFICE DEVICE FOR GAUGING THE CUTTING OF RAFTERS 3 Claims.

This invention has relation to carpenters implements and comprehends an improved device for facilitating the computation or determination of the lengths and angles of rafter cuts.

The invention broadly aims to provide a device of the indicated character by means of which the vaverage carpenter may expeditiously compute and with the aid of the usual steel square mark the lumber for the various cuts to be made in Aiashioning common rafters, hip and valley rafters, and jack rafters.

More particularly the invention resides in a device of the character set forth and for the purpose specified which includes a base having graduations, lines and indicia on one surface thereof and cooperative graduated sliding and swinging members adjustable to positions coinciding with the building and roof measurements to compute and determine the lengths of the various rafters and the heel, plumb and angle cuts to be made.

Other objects of the invention reside in the provision of a device of this character which is comparatively simple in its construction and mode of use, inexpensive to produce, highly efficient in its purpose and which is small and compact whereby it may be readily carried in the carpenters kit or pocket.

With the above enumerated and other objects in view, reference is now made to the following specification and accompanying drawing in which there is disclosed a preferred embodiment of the invention, while the appended claims cover variations and modifications thereof which fall within the scope of the invention.

In the drawing:

Fig. 1 is a face view of the device constructed in accordance with the invention, illustrating the slide member and pivoted arm in adjusted set position.

Fig. 2 is an end edge view thereof as viewed from the left hand edge of the device.

Fig. 3 is a face view illustrating the slide member and pivoted arm in folded inactive compact position for storage of the device.

Fig. 4 is` a vertical sectional view taken approximately on. the line 4--4 of Fig. 3.

Referring to the drawing by characters of reference, Ill designates the base of the devicel which is preferably of rectangular configuration having parallel opposite longitudinal side edges Il and I2 and a plane upper surface I3 which is provided with a longitudinally extending line I4 adjacent to and parallel with the side edge I2 and adjacent one end edge with a perpendicular transverse line I5. The line I4 is subdivided by longitudinally spaced graduations I6 having associated indicia Il beginning at the line I5.

A pair of longitudinally extending lines I8 and I9 are also inscribed on the upper surface I3 and 5 said lines are parallel to each other and to the line I4. The line I8 has associated therewith indicia 2E) which is here designated common rafter, while the line I9 has associated therewith indicia 2l, here designated hip or valley mi rafter. The line I4 together with its graduations I5 and indicia I'lhas further indicia 22 associated therewith designated the rise,

A slide member designated generally by the reference character 23 is mounted for guided 1P sliding movement with reference to the base I0 and said member 23 is preferably of T-shaped construction having a longitudinally extending head 24 which is formed with a groove 25 in its inner edge to slidably fit over the side edge I2 of the base. The slide member 23 further includes a slotted arm 26 disposed at an angle to the head 2li and extending transversely of the base I0 with the base received by the slotted portion so that the arm 26 straddles the same, and the upper surface of the portion of the arm 26 which overlies the base is provided with a series of graduations 2l which start at the line III and extend throughout its length to the free end thereof. Indicia 28 is associated with the grad uations and the arm 26 is also provided with indicia 29 designated the run. In order to lock the slide member 23 in adjusted relation to the base, a set screw 30 having a knurled manipulating head 3l is threaded through the outer end edge of the slide arm 26 and is designed to be impinged against the side edge'l I of the base.

The device further includes a swinging arm 32 which is mounted to swing on a pivot 33 having a vertical axis located at the intersection of the lines i4 and I5 adjacent one corner of the base, the edge 34 of the swinging arm intersecting the axis of the pivotal connection of the arm and said edge being provided with a line of graduations 35 and associated indicia 3S starting at the pivotal point of the arm.

The arm is disposed between the resilient furcations of a bracket 3l and the arm is secured in adjusted angular position by means of a thumb nut 38 which threadedly engages the pivot 33 for 50 frictionally clamping the arm between the furcations. In order to limit the swinging of the arm 32 to a position parallel with the head 24 of the slide member, a clip 39 is provided on the head 24 of the slide member.

ione-half inches.

The upper plane surface I3 of the base is provided with curved lines 4D and 4I which extend from the axis of the pivot 33, diverge with reference to each other and terminate at the oppositeY end edge of the base. These curved lines are respectively designated by the indicia 42 and 43 as bevel for hip or valley rafter and bevel for jack rafter.

In use and operation, when it is desired to determine the length of a common rafter and the angle ofthe heel and plumb cuts thereof, the slide is first moved so that the graduated edge of the slide arm coincides with the graduation I6 and indicia Il corresponding to the rise of the roof. Y The set screw 30 is then tightened to retain the adjustment and the swinging arm 32 is then swung to a position where its graduated edge coincides with the graduation 2l and indicia 28 which corresponds to the run which is half the width of the building. The graduation 35 and indicia 35 on the swinging arm 32 at the point of intersection of the graduated edges of the arms 26 and 32 will give the length of the rafter. By use of the usual carpenters steel square, the angles of the heel and plumb cuts and the bevel cuts for roofs of equal pitch are obtained as follows: Assuming that the run is fifteen feet and the rise fourteen feet, first set the slide member at the base graduation I6 indicated by the indicia il as fourteen, then tighten the set screw 3l?. The swinging arm 32 is then adjusted at an angle where its-edge 34 intersects the graduated edge of the arm portion 26 of the slide member 23 at the graduation 21 which correspends to the run, namely fifteen feet. The graduation 35 indicated by the indicia 36 on the swinging arm 32Will indicate the length of the common rafters, namely twenty feet, six and For the purpose of obtaining the heel and plumb cuts so that the graduation marked twelve on the blade of the steel square may be used as one measurement, tighten the clamping nut 38 to retain the swinging arm in set position and move the slide until the graduated edge thereof coincides with the intersection of the graduated edge 34 with the common rafter line i8 and tighten the set screw 30. The swinging arm^32 is now released and swung to the out-of-the-way position illustrated in Fig. 3 of the drawing and the base graduation where the slide member arm 26 is now adjusted will givethe other reading as eleven and one-quarter inches for the steel square tongue. When the steel square is placedv on vthe lumber with the twelve inch blade graduation at one edge of the lumber and the eleven and one-quarter inch tongue graduation at the edge of the lumber, the marking of the lumber along the edge of the blade will give the heel out while the marking of the lumber along the edge of the tongue will give the plumb cut.

To'determine the heel vand plumb cuts for the valley rafter, read the graduation at the point of intersection of the hip or Valley rafter line designated i9, with the slide arm 26, and the reading for the steel square will then be eleven and one-quarter inches on the tongue and seventeen inches on the blade, thelatter being the reading shown at the hip and valley rafter line.

To determine the setting of the steel square for the bevel cut of a hip or valley rafter, read the graduation on the slide arm 26 at the intersecton with the curved line designated bevel for hip or valley rafter which, in the example given, will be found to be nine and threeeighths inches which combined with the base graduation at the intersection of the slide arm 26, is eleven and one-quarter inches. The steel square is then laid on the edge of the lumber and marked along the tongue of the steel square.

The plumb cuts at the opposite endsV of the jack rafters are the same as thaplumb cuts for the common rafter and the bevel of the lower plumb cut which is to rest against the side of the valley rafter is obtained by reading the base graduation which shows eleven and one-quarter inches and the slide graduation at the intersection of the curved line marked bevel for jack rafter which is found to be eight and one-quarter inches.

In order to determine the length of the valley rafter, adjust the swinging arm 32 to the point of intersection of the graduated edge of the slide arm with the line i9 designated hip or valley rafter and tighten the clamping nut 38. Then move the slide to the base graduation I6 which corresponds to the rise of fourteen feet and read the graduation 35 on the swinging arm 32 at the point of intersection of the graduated edge of the slide arm 26 with the swinging arm 32. This, in the example being given, will show twenty-ve feet, six inches.

To determine the difference in length between the common rafter and the rst jack rafter, move the slide arm 26 to the base graduation eleven and one-half, set therrswinging arm 32 yto the point of intersection of the line 4|, designated bevel for jack rafter, tighten the swinging arm in this position and then move the slide arm, 26 to the point where it intersects the edge 34 of the swinging arm 32 at the graduation 2l on the slide arm which corresponds to the spacing of the jack rafters, which spacing has been predetermined, say for example, as sixteen inches apart. By then reading the graduation I6 and indicia il on the base at the intersection of the graduated edge of the slide arm, the difference in length between the common rafter and the first jack rafter, as well as between each of the succeeding jack rafters, will be obtained in inches and Will in the example given be twenty-one and seven-eighths inches.

What is claimed is:

l. In a device for computing rafter cuts, a base having a plane upper surface, a slide member overlying and extending across the upper sur` face of the base, vmeans mounting the slide member for guided sliding movement lengthwise of the base, an arm pivoted adjacent one corner of the base, means for locking the slide member and arm respectively in adjusted relation to each other, and curved lines on the surface of the base extending from the pivotal point of the arm for obtaining readings to determine the angle of the bevel cuts for the hip or valley and jack rafters.

2. In a device for computing rafter cuts, a rectangular base having a surface inscribed with lines and indicia, a T-shaped slide member having a slotted arm portion straddling and extending across opposite surfaces of said base, graduations and indicia on the surface of the arm portion overlying the inscribed surface of the base, a slotted head portion of said slide member engaging over one edge of the base for mounting the slide member for guided sliding movement lengthwise of the base, an arm pivoted adjacent one corner of the` base having graduations and indicia thereon, and means for locking the slide member and arm respectively in adjusted relation to each other, the lines on the surface of the base being so arranged as to beintersected by the slide member and the pivoted arm for designating the points of reading of the graduations to determine the length of common, hip and valle-y rafters and 5 the angles of the cuts to be made.

3. A device for computing rafter cuts including a base having a plane surface bearing a length- Wise line having graduations for indicating the rise, a pair of parallel lines spaced therefrom and 10 from each other for use in computing the cuts of common rafters and hip or valley rafters respectively, and divergent curved lines ,for use in computing the bevel cuts of the jack rafters and hip or Valley rafters respectively, a slide member overlying the surface of said base extending thereacross perpendicular to the parallel lines, mounted for guided sliding movement lengthwise thereof and having graduations indicating the run and cooperating With said parallel and curved lines to compute said rafter cuts, a graduated arm pivoted to said base at the intersection of the curved lines with each other and with the graduated line indicating the rise for the purpose of computing the length of the rafters, and means for locking the slide member and arm respectively in adjusted positions.

ERIK O. KARLSON.

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