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Патент USA US2412100

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'Del¢._3,1946.^
`NQSMWH
PROTRACTOR
Filed Nov. 29. 1944
'
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`
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
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1
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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.
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