US3304614A - Selectable pitch rafter cutting guide - Google Patents

Description

Wm. H, 1%? A. A. ADAMS 3,3M,6M

SELECTABLE PITCH RAFTER CUTTING GUIDE Filed Oct. 27, 1964 O .l O 6 o o o 1 RISE PER FOOT (mcuss) 45 Z 5L 4- INVENTOR.

A RTHUR A. ADAMS BY Mm/ ATT RNEYS 3 304,614 SELECTABLE PITCH RAFTER CUTTING GUIDE Arthur A. Adams, 1764 Bayovista Ave, San Pablo, Calif. 948% Filed Get. 27, 1964. Ser. No. 406,753 1 Claim. (Cl. 33-75) This invention relates generally to the cutting of rafters to provide a predetermined pitch or rise per foot, and is more particularly directed to a guide which facilitates the expeditious cutting of rafter notches and end faces at proper angles to provide any one of a number 'of predetermined pitches adjustably selectable by said guide.

The pitch of a rafter is determined by the complementary angles of a right triangular notch which is cut therein to receive a roof joist. In addition, at least the end of the rafter furthest removed from the notch is cut at an angle which provides an end face parallel to the short side of the notch for purposes of providing a mitered joint with an abutting rafter at the apex of the roof. In the construction of a given roof it is necessary to provide a substantial number of duplicate rafters having notches and end faces cut at angles commensurate with the desired pitch of the roof. Conventionally, the angles required to provide the desired pitch are computed and for each rafter the required location of the notch with respect to the rafter ends is marked by laying off the dimensions specified by the building plari. Thereafter, the outline of the notch is marked on each rafter at the pre-measured location with the aid, for example, of a miter gauge set at the predetermined angles of the sides of the notch. In a similar manner a out line is marked on the apex end of each rafter at the angle of the short side of the notch. The notches and rafter ends are then cut along the marked guide lines. It will be appreciated that the foregoing conventional procedure of cutting rafters is quite tedious and time consuming, and that extreme care and accuracy must be exercised in accomplishing same to insure that all rafters are substantially identical within close tolerances.

It is therefore an object of the present invention to provide a rafter cutting guide which facilitates the expeditious marking of notch and end cut guide lines commensurate with the provision of any one of a number of preselectable pitches.

Another object of the invention is the provision of a rafter cutting guide of the class described and a method of using same to substantially identically mark notch and end cut guide lines on a plurality of rafters without duplication of preliminary measurements and guide adjustment whereby the rafters may be marked for cutting in a minimum of time and with a minimum of effort.

It is a further object of the invention to provide a rafter cutting guide which is of simple low cost construction.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form nited States Patent ()fitice of the invention which is illustrated in the drawing ac- 3,3M,i4 Patented Feb. 21, 1957 supporting work bench illustrating a method of using the guide to mark notch and end cut guide lines on the rafter.

FIGURE 4 is an end view taken at line 4-4 of FIG- URE 3.

FIGURE 5 is a fragmentary elevation sectional view of a rafter construction.

Referring now to the drawing, FIGURES 1 and 2 in particular, there will be seen to be provideda rafter cutting guide 11 including a plate 12 having right angularly intersecting straight edges 13, 14. Straight edge 13 is calibrated in terms of inches, as indicated at 15, increasing in a direction away from edge 14. The guide further includes an adjustable .pitch selecting member 16 mounted upon the plate 12 for movement to different selectable positions of inclination with respect to straight edge 13. These different inclined positions are calibrated on the face of the plate, as indicated at 17, in terms of pitch expressed, for example, as inches of rise per foot. If the straight edge 13 is considered as a horizontal reference plane, the member 16 in any given one of the selectable positions is simulative of a rafter having a pitchcorrespondin-g to the associated calibration of such position.

In the preferred construction of the guide 11 briefly outlined above, the plate 12 is in the form of a trapezoid with straight edges 13, 14 being two sides thereof. The trapezoidal plate further includes an edge 18 parallel to edge 14 and perpendicular to edge 13. Such edge 18 is shorter than edge 14 and an angular edge 19 extends therebetween. The plate 12 may as Well be of rectangular configuration, however it will be appreciated that a saving in the material requirements of the plate is realized where same is trapezoidal.

The pitch selecting member 16 is preferably provided as an elongated rectangular bar having parallel side edges 21, 22 and parallel end edges 23, 24 right angularly related to the side edges. To facilitate movement of the member 16 to the different positions of inclination with respect to straight edge 13, the member is pivotally mounted on the underside of plate'12 at a point 26 inwardly adjacent edge 18 and inwardly spaced from edge 13. To this end, there is preferably provided a screw 27 which extends through an aperture 28 in the plate at point 26, and an aperture 29 in member 16 on the longitudinal center line thereof and inwardly spaced from end edge 23. A wing nut 31 is in turn threadably secured to the free end of the screw. With the wing nut loosened, the member 16 may thus be pivoted to various positions of inclination with respect to the edge 13. It is particularly important to note that in any position of member 16, the opposite end edges 23, 24 thereof are disposed outwardly from the edges 18, 14 of the plate. In addition, the edge 21 of member 16 is inwardly spaced from plate edge 13 when the member is positioned parallel thereto. The advantages of such arrangement will become apparent from a subsequent description of a preferred method of using the guide.

Considering now preferred means for locking pitch selecting member 16 in different inclined positions corresponding to the pitch calibrations 17, there are preferably provided a plurality of indexing apertures 32 through plate 12 equally circumferentially spaced on an arc centered at the pivot point 26 of the pitch selecting member. The indexing apertures 32 are thus all disposed at the same radial distance from pivot point 26, and an aperture 33 through the member 16 at the longitudinal center line thereof and spaced at such distance from aperture 29 is hence registerable with the respective indexing apertures as the member is pivoted to its various inclined positions. A wing nut 34 threaded upon the free end of a screw 36 inserted through one of the indexing apertures 32 and the registering aperture 33 of member 16, then serves to lock the member in the corresponding inclined position. The indexing aperture closest to the edge 13 is positioned such that when the aperture 33 of member 16 is registered therewith, the member is parallel to the edge 13. This indexing aperture hence corresponds to zero pitch. Each successive indexing aperture is perpendicularly spaced from a line through the center of the preceding aperture parallel to edge 13 by a fixed predetermined increment selected to correspondto a convenient incremental unit of pitch. More particularly, where the pitch calibrations 17 are expressed in terms of successive integral inches of rise per foot, the fixed increment of spacing between indexing apertures in inches is equal to the radial distance between the pivot point 26 and indexing apertures in feet. Thus, for example, where the radial distance is 6 inches, or /2 foot, the increment of spacing between indexing apertures is /2 inch. The pitch calibrations 17 in inches of rise per foot are then consecutive integers from zero provided on the face of plate 12 opposite the successive indexing apertures.

In some instances it may be desirable to provide the pitch calibrations 17 in smaller incremental units than the integral inches of rise per foot afforded by the above described arrangement of the indexing apertures 32. For example, increments of /2 inch of rise per foot have proven convenient in practice. However, it may be impractical to provide additional indexing apertures on the same are as apertures 32 and circumferentially intermediate same because of the close aperture spacing which would result. Accordingly, indexing apertures 37 are preferably provided on a different are that is concentric with and radially spaced from the arc of apertures 32. The apertures 37 are located on radii which are circumerentially centrally intermediate the radii of apertures 32. The apertures 37 are thus circumferentially spaced by the same amount as the apertures 32, and successive apertures 37 thus have a pitch increment of one inch of rise per foot. However, since the apertures 37 are centrally intermediate the apertures 32, each I aperture 37 corresponds to a /2 inch rise greater than the integral rise corresponding to the immediately preceding aperture 32. Thus, the aperture 37 between the 1 and 2 inch rise apertures 32 corresponds to a pitch of 1 /2 inch rise ,per foot, etc. In order to lock the member 16 at any of the added V2 inch rise positions of apertures 37, the member is provided with an aperture 38 which is registerable with apertures 37 and is therefore spaced from aperture 33 by an amount equal to the radius of the are upon which the apertures 37 are disposed. The screw 36 and wing nut 34 may be employed to lock the member 16 at any of the positions corresponding to apertures 37 in similar fashion as the positions corresponding to apertures 32.

Both the plate 12 and pitch selecting member 16 of the guide 11 are fabricated from a durable substantially rigid material so as to provide a high degree of dimensional stability and accuracy. Accordingly, the plate 12 and member 16 are preferably formed of heavy guage metal such as aluminum, relatively thick hard plastic sheet, or the like.

In the use of the guide 11 to facilitate the cutting of the notch and end faces of a rafter 39, the pitch selection member 16 is set to a desired pitch corresponding to one of the calibrated indexing apertures 32, 37. For example, if the rafter is to be cut to provide a pitch of 4 inches rise per foot, the member 16 is pivoted to a position wherein aperture 33 registers with the aperture 32 designated by the numeral 4 of the pitch calibrations 17. The screw 36 is inserted through the registering apertures and the wing nut 34 is tightened upon the free end of the screw to thereby lock the member 16 in position. The guide is then placed upon the rafter 39 with the underface of the plate 12 engaging the surface, and the edge 21 of member 16 engaging a side edge of the rafter as shown in FIG- URES 3 and 4. The guide is positioned with straight edge 13 intersecting the opposite side edge of the rafter to that engaged by member 16 at a point spaced from one end of the rafter by a pre-measured distance determined from the dimensions of the building plan, as indicated in phantom line in FIGURE 3. A cut guide line 41 is marked on the surface of the rafter along the straight edge 13. Using the calibrations 15 adjacent such straight edge, a distance is measured inward from the edge of the rafter along the line 41, and a point marked off to correspond to the Width of a joist which the rafter notch is to receive. The guide is then moved along the rafter until the straight edge 14 intersects line 41 at the marked off point as shown in full line in FIGURE 3. A cut guide line 42 is now marked on the surface of the rafter along the straight edge 14. The guide lines 41, 42 when cut define a right triangular notch, the sides of which are at the proper angles to provide a pitch of 4 inches rise per foot when the notch engages a roof joist. The guide may be similarly positioned adjacent the distal end of the rafter relative to the notch and a cut guide line 43 marked along straight edge 14 to facilitate cutting of an angular end face commensurate with a 4 inch rise per foot pitch. After the rafter 39 is cut along the guide lines 41, 42, 43, it may be erected in the roof construction depicted in FIGURE 5, to provide a roof having a 4 inch use per foot pitch. More particularly, the notch formed by cutting along lines 41, 42 is engaged with a roof joist 45 and the angular end face formed by cutting along line 43 is butted with the angular end face of a similar rafter 39 to provide a mitered apex joint as indicated at 50. By virtue of the notch and end face angles determined by the guide 11, the rafter has the selected 4 inch per foot pitch.

Considering now a method of using the guide to mark a number of rafters for cutting as duplicates of the rafter 39, the rafter 39 is preferably supported upon a bench 44, or the like, prior to the marking of lines 41, 42, 43. In this regard, the rafter is located in a predetermined position on the bench, as by means of end and side locator blocks 46 and 47 mounted on the surface of the bench for abutment with an end and side of the rafter. Thus rafter 39 and subsequent rafters when abutted with the blocks 46, 47 occupy identical positions with respect to the support surface of the bench. With the guide 11 disposed on rafter 39 at the predetermined position thereof for the marking of line 41, a nail 48 is driven into the bench, or a stop is otherwise provided at a position of engagement with the end edge 24 of member 16. Similarly, with the guide positioned for the marking of line 42 on the rafter 39, a nail 49, 01 equivalent stop, is secured to the bench at a position of engagement with the end edge 23 of member 16. An apex cut line locator stop (not shown) may likewise be provided in engagement with end edge 23 of member 16 when the guide is positioned for the marking of line 43 on the rafter 39.

With the stops thus located on the bench 44 during the marking of the initial rafter it will be appreciated that duplicate marking of subsequent rafters may be accomplished in a highly expeditious manner which does not require measurement. Each subsequent rafter is merely abutted with the locator blocks 46, 47, and the guide 11 is placed upon the rafter with, for example, end edge 24 of member 16 engaging nail 48. A line is then marked on the rafter along edge 13. The guide 11 is now moved along the rafter to engage the end edge 23 of member 16 with the nail 49 and a line is marked along edge 14 to thereby complete the cut guide lines for the notch. Thereafter, the end edge 23 of member 16 may be engaged with the apex cut line locator stop, and such cut line marked on the rafter along edge 14.

V Although the use of the guide has been previously described with respect to the marking of cut guide lines,

it will be appreciated that the guide may as well be employed in a similar manner to facilitate direct guided cutting of rafters with a saw without preliminary marking of guide lines.

What is claimed is:

A method of marking rafters for cutting by means of a guide including a plate having right angularly intersecting straight edges with a first of said edges calibrated in units of linear measure, and an elongated pitch selecting member pivotally secured to said plate for selective movement to different positions of inclination with respect to said first straight edge respectively corresponding to different rafter pitches, said member projecting beyond the margin of said plate, comprising the steps of supporting a rafter on a surface at a predetermined location thereof, placing said guide upon said rafter with said plate engaging the exposed face of said rafter and a side edge of said member engaging a side edge of said rafter, moving said guide along said rafter to a first position wherein said first straight edge intersects the opposite side edge of said rafter from that engaged by said member at a predetermined point, marking a cut guide line on said exposed face of said rafter along said first straight edge, securing a first stop to said surface at a position of engagement with a first end of said member in said first position of said guide, measuring a predetermined distance inward from said opposite side edge of said rafter along said line with the calibrations of said first straight edge, moving said guide along said rafter to a second position wherein said second straight edge intersects said line at said predetermined distance from said opposite side edge of said rafter, marking a second cut guide line on said exposed face of said rafter along said second straight edge, securing a second stop to said surface at a position of engagement with the second end of said member in said second position of said guide, removing said rafter from said support surface, supporting a second rafter upon said surface at said predetermined location, placing said guide upon said second rafter with said plate and member respectively engaging the exposed face and a side edge thereof and said first end of said member engaging said first stop, marking a cut guide line on the exposed face of said second rafter along said first straight edge, moving said guide along said second rafter to engage said second end of said member with said second stop, and marking a second cut guide line on the exposed face of said second rafter along said second straight edge.

References Cited by the Examiner UNITED STATES PATENTS 383,242 6/1888 Palmer 33-93 X 842,999 2/1907 Calhoon 33-93 X 855,734 6/1907 Terry 33- X 944,799 12/1909 Lytle 33 93 1,084,973 1/1914 Stanwood etal 33-93 2,651,333 9/1953 Spinney 1436.43 2,901,832 9/1959 Hulen 33-1845 3,115,707 12/1963 Watts 33- 93 LEONARD FORMAN, Primary Examiner. ISAAC LISANN, Examiner. H, N. HAROIAN, Assistant Examiner.

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