Geometrical instruments – Straightedge type – Plural straightedges – relatively moveable
Patent
1984-09-04
1986-09-16
Stearns, Richard R.
Geometrical instruments
Straightedge type
Plural straightedges, relatively moveable
B43L 706
Patent
active
046114076
DESCRIPTION:
BRIEF SUMMARY
This invention relates to guide or marking tools.
Many instruments or tools have been proposed in the past to enable guide lines or marking lines to be marked on a workpiece at a predetermined angle to another line or edge. It is a general disadvantage of such tools that the point of intersection between the reference line or edge and the guiding or marking edge changes when the tool is adjusted for different angles. This necessitates in use a repositioning of the tool on the workpiece. It is a further disadvantage of such tools that it is difficult to incorporate a length marking scale on the guiding or marking edge as the zero or reference point of the scale shifts relative to the reference line or edge as the angle of the tool is adjusted. Accordingly in use, the angle is marked and then a tape measure is used to measure along the marked line. This can lead to inaccurate marking. Similar disavantages are also found in other devices that are used for marking or measuring various angles such as in various types of drafting or surveying equipment.
It is an object of this invention to provide guide or marking tools which will alleviate the abovementioned disadvantages and which will be reliable and efficient in use. Other objects and advantages of this invention will hereinafter become apparent.
With the foregoing and other objects in view this invention in one aspect resides broadly in a pivot assembly for adjustably connecting a pair of members together for relative pivotal movement, said pivot assembly an including arcuate guide faced on one said member; locating means on the other said member adapted to abut said guide face so as to locate said other member relative to said one member and retaining means for securing the members together.
If desired there may be provided a plurality of guide faces on said one member and in the preferred form the guide face or faces are sectorial and are arranged concentrically with one another. The guide face or faces may be formed by providing sectorial slot or slots or grooves in said one member. The locating means may be in the form of a complementary abutment face on said other member adapted to abut said guide face or it may be constituted by a pair of spaced pins or the like fixed to said other member and adapted to abut said guide face at spaced locations therealong. The pins may be fixed or rotatable if desired.
Preferably the retaining means is in the form of a threaded stem fixed to one said member and passing through a slot in the other said member, said slot being disposed concentrically with said guide face and there being provided a nut on said threaded stem rotatable to secure the members together.
Alternatively the retaining means may include or be constituted by a captive arcuate slot or groove in one said member concentric with or constituting said guide face and complementary locating means in the other said member adapted to engage and be held captive in said slot. The captive slot may be in the form of a T-slot or a re-entrant recess of any desired configuration.
It is also preferred that the guide face is formed as a sector of a cylinder or truncated cone disposed such that its axis is coincident with a straight guide or marking edge of one said member and that abutment means having an abutment plane coincident with said axis its provided on the other said member.
In a further aspect this invention resides broadly in a guide or marking tool comprising a stock assembly and a blade assembly, the latter having an intermediate mounting segment connected pivotally to one end of said stock assembly for pivotal movement about a pivot axis and being provided with angle markings whereby its rotational position about said pivot axis may be monitored and a guiding or marking blade supported by said intermediate mounting segment for movement therewith and arranged with its guiding or marking edge coincident with said pivot axis and said stock assembly having an abutment face disposed in a plane containing said pivot axis whereby it may be engaged against a ref
REFERENCES:
patent: 161392 (1875-03-01), Dodd
patent: 714404 (1902-11-01), Schaller
patent: 794569 (1905-07-01), Thomas
patent: 1331415 (1920-02-01), Civitts
patent: 2435529 (1948-02-01), Brockley
patent: 2972191 (1961-02-01), Kichta
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