Geometrical instruments – Scriber – Curved line
Patent
1977-07-19
1979-04-03
Haroian, Harry N.
Geometrical instruments
Scriber
Curved line
33157, B43L 902, B43L 820
Patent
active
041469658
ABSTRACT:
A drawing instrument comprises a pair of die-cast limbs pivotally connected together to form an assembly at the inner ends thereof. A bow top has an interior hole and fork limbs having inside faces embracing the assembly of the ends. A centralizing member is held between the inner ends of the pivoted die-cast limbs. The centralizing member includes an elongated pivot receiving hole and first and second keying poles. A first die-cast keying projection is integrally formed at the inner end of a first one of the pivoted die-cast limbs. A first arcuate slot is provided in the inner end of the first pivoted die-cast limb. A second die-cast keying projection is integrally formed at the inner end of the second one of the pivoted die-cast limbs. A second arcuate slot is disposed in the inner end of the second pivoted die-cast limb. The first and second die-cast keying projections engage the second and first arcuate slots, respectively. The first and second die-cast keying projections engage the first and second keying holes in the centralizing member to key the centralizing member to the inner ends of the pivoted die-cast limbs. The centralizing member has a structural configuration to project up into the interior hole of the bow top and is further effective to press against a side wall of the interior hole when there is angular movement of one of the pivoted limbs with respect to the other pivoted limb. Consequently, the structural configuration of the centralizing member causes the bow top to turn and keep central. Stop means engageable with the inner ends of the pivoted limbs are effective to act against the angular opening out movement of the pivotal limbs beyond a predetermined angular limit. Thus, the two die-cast projections cannot bear against the ends of the respective arcuate recesses or slots before the stop means on the bow top bear against the inner ends of the die-cast limbs. BACKGROUND OF THE INVENTION
REFERENCES:
patent: 723041 (1903-03-01), Schwarzer
patent: 902257 (1908-10-01), Schoenner
patent: 2080917 (1937-05-01), Hochman
patent: 2644239 (1953-07-01), Bellstaedt
patent: 3842508 (1974-10-01), Gentils
Haroian Harry N.
Helix International Limited
Markva Neil F.
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