'Del¢._3,1946.^ `NQSMWH PROTRACTOR Filed Nov. 29. 1944 ' l@ f ` 2,412,100. Patented Dec. 3, 1946 2,412,100 ] `- UNITED < STATE s PArt-:Nr¿*oI-‘Flcli 5 Neily C. smith, . ritoTnAoîifoR_V Minneapolis, MMinn. " « ' Ap‘pneaiion November 29,1944, serial No. 565,697 . . 1 . . of‘a circle having' _its center at ~’the axis >of said turret II. This section of the Aturret || is -beveled to a relatively sharp edge at its underside,v as » lt/lyì'present invention relates vto improvements in protractors of the type having a rotatable turret andra blade slidably mounted thereon. The object of this invention isvto provide an extremelyisirnple and highly eflicient protractor" having commonV means for simultaneously locking the'turret against rotation and the blade against sliding movement. Other objects vof the invention will be ap parent from‘the> following description, reference :being had to the accompanying drawing. 3 To _the above end, generally stated, the inven tion consists of the novel devices and‘combi nation of devices hereinafter described and de ñned in the claims. , indicated at I2. 5 ` ' ^ ` `ï' " A thin narrow blade I3 is mounted in a chan nel I4 in the under side of the >turret || `for endwise sliding movement. This channel'M is in the opposite side of‘ the turret |I from' the intermediate portion of the bevel I2. A springY member I‘5 in the channel I4, between one side thereof and the adjacent longitudinal'edge "of the blade I3, yieldingly holds said blade pressed against the other side of said channel -whereby the blade I3 >is frictionally held where endwis'e adjusted in the channel I4. The spring'mem-` ' " In the accompanying drawingïwhich illustrates ber I5 is held in the channel I4 by a pin I6. The the invention, like characters indicate like parts blade I3 rests ñatwise directly> on the head 8 and the central portion of the turret I I also rests directly on said head. Said turret l I, lat its outer 20 portion, has a working clearance with the body throughout the _several views. Referring to the drawing: Fig. 1 is a plan View of the improved pro tractor; Fig. 2 is a bottom plan View of the turret and the blade removed from the body of the pro tractor; Fig. 3 is a fragmentary plan view of the body with the turret and the blade removed therefrom; Fig. 4 is a view partly in side elevation and partly in section taken on the line 4-4 of Fig. 1, on an enlarged scale; Fig. 5 is a plan view of the Washer removed from the protractor, as shown in Fig. 4; and Fig. 6 is a bottom plan View of the washer as shown in Fig. 5. The numeral 'l indicates the body of the pro tractor which, as shown, is in the form of a blade, the longitudinal edges of which are parallel. One end portion of the body ‘I is en larged to afford a head 8. At the center of the head 8 is an upstanding tubular pivot 9, the lower end portion of which is reduced in diameter and mounted in a hole in said head. An annplar shoulder l0 is formed by reducing the lower end portion of the pivot 9 and which shoulder I0 rests directly on the head 8. The lower end of 1, see Fig. 4. The longitudinal edge of the blade I3 that is in direct engagement with the side of the channel I4 has dove-tailed engagement with the r vturret I I. The upper end portion of the pivot 9 extends outwardly of the turret II and is re duced in diameter and diametrically opposite sides of this reduced portion are flattened, as indicated at Il. A washer I8 is mounted on 30 the reduced outer end portion of the pivot 9 and the hole therein has the same contour as the respective portion of the pivot 9 and is thereby held from turning on the pivot 9. The under side of the Washer I8 is dished at I9 so that only its outer marginal portion bears on the turret I I. A screw 20 extends into the tubular pivot 9 and has threaded engagement therewith. This screw 20 has a large head 2|, the periphery of which is beveled and knurled. On the under 40 side of the screw head 2| is a thin hub 22 that bears directly on the washer I8. _ Obviously, by tightening the screw 20, the turret II will be frictionally clamped onto the lbody 'l and thereby held against rotation and the pivot 9 is upset within the plane of the body at the same time the blade I3 will be friction 'l to rigidly secure the pivot 9 to the head 8 with ally clamped onto thebody 'I and thereby held against endwise sliding movement. It will be its axis perpendicular to the plane of the body 1. This method of securing the pivot 9 to the noted that the screw head 2| extends outwardly of the washer I8 so that the same can be easily head 8 leaves the bottom of the body 'l perfectly smooth so that said body will rest flat on a 50 gripped with the ñngers. The size of the screw head 2| makes it very easy to manipulate. The support. turret II, the washer I8, the screw 20 and the A flat turret Il is mounted on the pivot 9 screw head 2| all have their axis at the axis for rotation about the axis thereof in a plane of the pivot which lends itself for accuracy and parallel to the plane of the body '|. Substan tially 180 degrees of the turret II is on the arc 55 easy assembly. The washer I8, due to its dished 2,412,100 3 under side, bears only on'its outer portion on the turret II. This structure gives an even pres sure on the turret in a complete circle that is 4 having an upstanding pivot, a turret turnably mounted on the pivot with freedom for axial movement and resting on the body, a blade mounted on the turret for endwise sliding move concentric to the pivot 9, thereby holds the tur ret II in a plane that is parallel to the plane 5 ment and resting on the body, a washer mounted on the pivot with freedom for axial movement, of the body 1 and prevents tilting thereof on held against relative turning movement and rest the pivot 9 and thus prevents undue wear and ing on the turret, a member having threaded en strain on said pivot. gagement with the pivot and bearing on the By reference to Fig. 4 it will be noted that there is a working clearance between the upper 10 washer and operable to simultaneously friction ally clamp the turret onto the body and thereby end of the pivot 9 and the hub 22. The dished hold the turret from turning on the pivot and under side of the washer I8 affords a good work frictionally clamp the blade between the body ing clearance between the shouldered upper end and the turret and thereby hold the blade from of the pivot 9 and said Washer and the surface of the turret I I underlying said dished portion of 15 sliding endwise relative to the turret and the body. the washer I8. 2. In a device of the class described, a body The body 1 and the blade I3 each Vhas Ythereon 'having an upstanding tubular pivot, a turret a scale of inches as indicated at 23 and 24, re turnably mounted on the pivot with freedom for spectively. A circle, outward of the curved por tion of the turret II and having its center at 20 axial movement, resting on the body, and having a channel in itsl under side, a blade mounted in the axis 4of the pivot 9 is divided into quarters, said channel for endwise sliding movement and and each quarter vgraduated into 90 degrees, Vas resting on the body, a Washer mounted on the indicated at 25. These degrees read from two pivot with freedom for axial movement, held diametrically opposite zero points. Tw'o zero marks 26 and 21 are shown on the turret II 25 against relative turning movement and resting on the body, a thumb-screw having threaded engage spaced 90 degrees apart for co~operation with ment With the tubular pivot with its head bear the degree graduations 25. By means of one of ing on the washer and operable to simultaneously these zero points 25 and 26, the turret II _may frictionally clamp the turret onto the body and be adjusted to position the blade I3 at a required angle relative tothe body 1 and the degree read 30 thereby hold the turret from turning on the pivot and frictionally clamp the blade between ing at .the other zero point will give the compo~ the body -and the turret and hold the blade from nent angle. A Vernier scale 28 on the turret II sliding endwise relative to the turret and the has _its zero point at the zero point 21 and reads body. in opposite directions therefrom. The close prox 3. The structure defined in claim 2 in which imity of the beveled edge of the turret II with 35 the Washer is dished on its underside and there the» degree markings 25 lends itself to easy and by engages the turret only at its perimeter. accurate reading of said degrees. vWhat I claim is: >1. In a device of .the class described, a body NE1L C. SMITH.