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Patented Sept. 30, 1947
.
UNITED
1
y
'
STATES
2,428,310
PATENT
' '
2,428,310
opp-ICE
" 7
~
DRAFTIN G INSTRUMENT
‘Ralph AllisonHendry, Truro, Nova Scotia,
.
~.
Canada
-. 4 Application August 30, 1944; Serial No. 551,893 7
3 Claims.
My invention relates to improvements in draft;
2
.
strument, the center pin M is ?rst placed in the
anchor block l3 and with the block held canted
on a work sheet, or the like, so that the point of
the pin I4 is visible beneath the block, said pin
is centered on a selected center point, the block‘
and pin then straightened up so that the anchor
anchor block l3 so that
the body I may be swung about the centered
anchor block I4 flat on the work.
The arcuate lines 9 are designated by suitable
accompanying and forming part of this appli
cation.
degree and minute markings indicating the de
In said drawing:
_
Figure 1 is a view in plan of my improved in
strument in the preferred embodiment thereof,
gree of curve of the arcs to a predetermined scale
15 as shown in Figure 1.
It is not believed to be essential to a proper
Figure 2 is a view in edge elevation,
Figure 3 is a view in rear elevation drawn to
understanding of the invention to describe all
possible uses of the same.
an enlarged scale,
Figure 4 is a view in plan of the bushing and 20
anchor block,
The uses described
in the following are deemed su?icient.
To lay 01f an angle from a given point on tan
gent, the term “tangent” meaning any straight
portion of a center line, following railway and
Figure 5 is a
in vertical section taken on
the line 5—5 of view
Figure 4, and
highway practice, center the anchor block I 3 on
Figure 6 is a
the given point and anchor said block on center,
view
in
perspective
of
the
anchor
25'
block.
/
Referring to the drawing by numerals, my im
proved instrument, as illustrated, comprises a
protractor-like body
mental form and of
Other uses of the instrument Will be apparent.
The foregoing will, it is believed, su?ice to im
part a clear understanding of my invention with
out further explanation.
Manifestly, the invention as described, is sus~
40
ceptible of modi?cation without departing from
graduated in degrees from the 45°
radius line 8
the appended claims.
to the 90° radius lines 6, 1, as shown at
I0’. Holes
H are drilled in the body I at the
What I claim is:
~
of
the tangent lines l0, and similar extremities
1. In an instrument of the class described, a
holes
at
the
45
approximate points of intersection
transparent body of substantially ninety degree
, lines 9 and the radius lines 6, ‘I.v of the arcuate
segmental form provided with an apertured axis
A cylindrical, axially bored anchor block l3,
forming tab, a bushing ?xed‘ on said tab con
higher than the bushing 5 for a purpose pres
‘
aperture in the tab, an anchor
ently seen, is provided for ?tting in the bushing 50
5, and a pointed
for ?tting in the
bore of the anchor block l3. A
‘
anchor pins l5
the anchor block l3.
In the use and operation of the described in 55 same to the work in centered position.
2. In an instrument of the class described, a
2,428,310
3
transparent body of substantially ninety degree
segmental form provided with an apertured axis
forming tab, a bushing ?xed on said tab concen
trically of the aperture in the tab, an anchor
block ?tting in said bushing and adapted to form
a bearing about which the bushing and body may
be rotated on a piece of work, means to center
said anchor block relative to a selected point on
the work, and means on said block to attach the
same to the work in centered position, the ?rst 10
work, and means on said block to attach the
same to the work in centered position, the last
mentioned means comprising bottom pins on the
block adapted to be forced into the work.
RALPH A HENDRY.
REFERENCES CITED
mentioned means comprising a centering pin,
block having an axial bore extending there
through through which the pin is adapted to be , _
extended.
block ?tting in said bushing and adapted to form
a bearing about which the bushing and body may
be rotated on a piece of work, means to center said
anchor block relative to a selected point on the
The following references are of record in the
?le of this patent:
is
3. In an instrument of the class described, a.
transparent body of substantially ninety degree '
segmental form provided with an apertured axis- "
forming tab, a bushing fixed on said tab concen
trically of the aperture in the tab, an anchor
vUNITED STATES PATENTS
Number
555,28’?
1,808,705
Name
Date
Horrigan _________ __ Feb. 25, 1896
Owen _____________ __ June 2, 1931
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